The practical advantage of understanding security door parts at the component level is significant. A facility manager who can identify a worn dogging shaft on a Von Duprin exit device and order the correct replacement part by number avoids both a full device replacement cost and a multi-day wait for a distributor quote. A locksmith who knows the difference between a chassis assembly for an ND Series lock and one for an ALX Series completes a service call in one visit instead of two.

This guide covers every major category of commercial security door parts, what each component does, what wears out first, and how to identify and order the right replacement. Browse the complete commercial door hardware parts catalog at SecurityParts.com.

What Security Door Parts Are Found on a Commercial Opening

A complete commercial door opening typically contains six to eight distinct hardware devices. Each device has its own parts structure, its own wear pattern, and its own parts catalog. Understanding which device category you are working on is the first step to ordering the right component.

Exit Device Parts: What Wears Out and Why

Exit devices are the most actively used hardware on any commercial door. On a high-traffic door in a school, hospital, or retail building, the push bar can be actuated hundreds of times per day. That cycle count is what determines which internal parts require attention first. For a full technical breakdown of exit device components by type and series, see the commercial exit device parts guide at SecurityParts.com.

Door Closer Parts: The Most Active Component on the Door

A door closer cycles every time the door opens and returns to closed. On a busy commercial entrance, that can mean 500 or more cycles per day. The arm assembly transmits mechanical load from the door to the frame on every single cycle, which is why arm components wear before the closer body itself. For detailed LCN closer component identification, see the door closer parts guide at SecurityParts.com.

Lock Parts: Cylindrical, Mortise, and Deadbolt Components

Commercial locks contain more individual components than any other hardware category, and the specific parts that apply depend entirely on the lock series and function. Getting the series right before ordering any lock component is the most important step in the parts identification process. For cylindrical lock component breakdown, see the cylindrical lock parts guide at SecurityParts.com. For mortise lock component identification, see the mortise lock parts guide at SecurityParts.com.

Mortise Lock Components

Mortise lock parts are more numerous and more model-specific than cylindrical lock parts. The Schlage L Series alone covers over sixty distinct model functions, and the chassis assembly, armor front, and cylinder trim components for an L9070 are different from those for an L9080. Confirm the exact model number stamped on the lock body before sourcing any mortise lock component. For the full breakdown by model and component category, see the Schlage L Series parts diagrams guide.

Electric Strike Parts and Deadbolt Parts

Electric Strike Parts

An electric strike replaces the standard strike plate and allows remote latch release as part of an access control system. The strike housing, keeper, and solenoid assembly are the main components. When an electric strike fails to release on a valid credential, the solenoid is typically the first component to check. When it fails to hold the door closed, the keeper and housing alignment need inspection before the solenoid is replaced. For a full component breakdown, see the electric strike parts guide.

Electric strikes are also used in access control integration alongside exit devices and locksets. For guidance on how electric strikes fit into a broader access control system, see the access control and commercial door hardware integration guide.

Deadbolt Parts

Deadbolts provide a secondary locking point on commercial doors where the primary lock function alone is not sufficient. The deadbolt cylinder, strike plate, tailpiece, and rose assembly are the main replacement components. Deadbolt strike plates are a frequent replacement on doors where the deadbolt is engaged under misalignment, which causes the strike pocket to elongate over time. For component identification on Schlage B Series deadbolts, see the deadbolt parts guide.

How to Identify Security Door Parts by Brand and Series

Correct parts identification is the difference between a repair completed in one service visit and a job that drags through two return trips and a wrong-part delay. Every security door part order should start with three pieces of confirmed information before any part number is looked up.

1. Find the brand name on the device body The brand name is printed or stamped on the mechanism case, the closer body, or the lock chassis. On commercial hardware, the brand is almost always visible without disassembly. The brand determines which parts catalog applies.
2. Confirm the series or model number The series designation appears near the brand name on a label or as a stamped code. For Von Duprin exit devices, this is a number like 98, 99, 22, or 88. For LCN closers, it is a four-digit number like 4040 or 1461. For Schlage locks, it is a letter-number combination like ND, L9070, or B60N. The series determines which specific parts apply and which parts do not cross-reference.
3. Use a parts diagram to confirm the component Parts diagrams show the exploded view of the device with every component labeled and numbered. Identifying the failed component visually against the diagram confirms the part number before anything is ordered. SecurityParts.com provides interactive parts diagrams for every supported brand and series.
4. Confirm finish if ordering visible trim components Lever trim, rose assemblies, end caps, and cover plates are finish-sensitive. The replacement must match the installed finish code. Sending back a satin chrome part when satin stainless was needed costs real time and money.
5. Note manufacture date for older devices On older devices, the manufacture date affects which dogging parts apply. Von Duprin exit devices manufactured before August 1997 use different dogging replacement kits from current-specification parts. The manufacture date typically appears near the model number on the device label.

Brand and Series Reference for Security Door Parts

Security Door Parts for Fire-Rated Openings

Fire-rated door hardware operates under specific requirements that go beyond what applies to standard commercial hardware. Every security door part replaced on a fire-rated opening must preserve the UL listing of the complete assembly. For a full overview of fire-rated door hardware requirements, see the commercial door fire rating guide.

OEM Parts Are Required on Fire-Rated Doors

NFPA 80 requires that fire door hardware be maintained using parts that preserve the original UL listing. A non-OEM replacement part installed on a fire-rated exit device or lock voids the UL listing and creates a compliance failure at the next annual fire door inspection. The failed inspection is not the worst outcome: a fire door that does not latch because a non-OEM latch kit was installed creates a liability that goes well beyond the inspection report.

OEM vs Aftermarket Security Door Parts

On standard interior doors in low-traffic applications, aftermarket parts sometimes function adequately in the short term. The problems appear on high-cycle commercial openings and on fire-rated assemblies. An aftermarket latch kit that does not meet the dimensional tolerances of the original part produces inconsistent latch engagement over time. An aftermarket dogging shaft that is slightly undersized strips faster than the OEM equivalent.

The decision is clear: use OEM parts for all fire-rated hardware, all Grade 1 ANSI/BHMA certified hardware in high-traffic applications, and any device where a parts failure has a direct security consequence. For a complete analysis of the OEM versus aftermarket parts decision on commercial hardware, see the OEM vs aftermarket commercial door hardware parts guide.

SecurityParts.com stocks only OEM replacement parts. Every component in the catalog is manufactured to the original specification, maintaining ANSI/BHMA certification and UL listing integrity on fire-rated and Grade 1 hardware.

How to Order the Right Security Door Parts the First Time

Commercial door hardware returns are expensive and delay repairs on openings that may be critical to building security or life safety. A few consistent habits eliminate most ordering errors.

• Always confirm brand, series, and model number before looking up any part number. Never order by description alone.
• Use parts diagrams to confirm the specific component visually before placing the order. SecurityParts.com provides diagrams for every supported brand and series.
• Confirm finish code before ordering any trim component: lever trim, rose, end cap, or cover plate.
• Confirm whether the device is panic or fire-rated before ordering latch kits, dogging parts, or cover plates.
• Check the manufacture date on older devices before ordering dogging parts, where pre-1997 and post-1997 devices may require different components.
• Inspect adjacent components when replacing a worn part. A failed dogging spring often means the dogging adapter and shaft are also near the end of their service life.

For troubleshooting guidance when a security door part failure is not producing an obvious symptom, see the commercial door hardware troubleshooting guide. For code-compliance guidance on panic hardware, see the panic hardware for commercial doors guide.

For guidance on ANSI/BHMA Grade ratings and how they affect parts selection across every hardware category, see the ANSI/BHMA door hardware standards guide.

This guide covers everything needed to identify, order, and service Von Duprin 9847 exit device parts: the CVR configurations, the most common failure parts, the 9847 vs 9947 model number difference, fire vs panic device compatibility, the WDC wood door variant, and the electrified upgrade options available on this device family. Browse the Von Duprin exit devices catalog or the Von Duprin brand parts page at SecurityParts.com. Call 845-935-0301 or visit the SecurityParts.com contact page for pre-order parts identification support.

What Is the Von Duprin 9847 Exit Device and Where Is It Used

The Von Duprin 9847 exit device is a concealed vertical rod exit device. It belongs to the 98/99 series, which is the institutional flagship exit device line from Allegion. The CVR configuration uses vertical rods that run inside the door stile, engaging a top latch at the door head and a bottom latch at the door threshold when the push bar is activated. Because the rods are concealed inside the door, no hardware is visible on the door face except the push bar itself and the latch bolts at the top and bottom edges.

This configuration makes the 9847 the specification of choice in three situations: double doors without a center mullion that require three-point locking, architectural environments where surface rod hardware is visually unacceptable, and hotel or healthcare reception areas where door face appearance is a design requirement.

The 9847 CVR is available in panic and fire exit hardware versions. The panic version (model 9847) supports cylinder dogging and hex dogging options. The fire version (model 9847-F) must positively latch on every door cycle and does not support any dogging. ANSI/BHMA A156.3 Grade 1 certification applies to the full 98/99 series including the 9847 configuration.

Von Duprin 9847 vs 9947: Understanding the Model Number Difference

This is the most common source of confusion when ordering parts for a CVR exit device. The 9847 and 9947 are not two different products. They are two model number designations for the same concealed vertical rod configuration within the 98/99 series.

The 9847 designation was used on devices manufactured up through the mid-to-late 1990s. The 9947 is the current designation in active production. The physical device, its rod hardware, latch assemblies, and mechanism case are functionally identical between the two designations. Allegion consolidated the naming when the series was updated.

What the prefix tells you is a separate matter entirely. The 98-prefix (as in 9847) indicates a smooth mechanism case. The 99-prefix (as in 9947) indicates a grooved mechanism case. Both use the same internal parts. The grooved case on the 99 series provides better grip surface on high-contact institutional openings, which is why healthcare and educational specifications often call for the 99 specifically.

How to Read the Von Duprin 9847 Model Number on the Device

The model number on a Von Duprin 9847 CVR exit device appears on a label near the mechanism case housing on the hinge side of the device body. The label typically shows the full model designation including configuration suffix: 9847, 9847-F, 9947, or 9947-F. On some older devices the label has worn, in which case the device configuration can be determined by the hardware visible at the door head and threshold.

The suffix tells you which replacement parts apply to the latch assemblies. The -F suffix means fire exit hardware. Without -F means panic hardware. This distinction changes which latch mounting bracket quantity is required per latch and whether dogging components are applicable at all.

Von Duprin 9847 CVR Configurations

The 9847 concealed vertical rod exit device is available in several configurations that affect which rod components, latch kits, and mounting hardware apply to your installation.

Von Duprin 9847 Parts: Most Common Replacements

These are the components that fail most frequently on the Von Duprin 9847 CVR exit device based on field replacement patterns. Every part number below applies to both the 9847 and 9947 designations on devices manufactured after August 1997.

Latch Assemblies

The top and bottom latch kits are the most frequently replaced components on CVR exit devices. They wear at the pivot points and at the latch bolt face on high-cycle openings. Latch kits are sold separately for top and bottom, and the quantity of latch mounting brackets required differs between panic and fire devices.

Rod Assemblies

The adjustable vertical rods are the structural element that transmits push bar activation to the top and bottom latches. Rods bend or deform on high-abuse applications. The top rod is adjustable for door height; the bottom rod kit includes the adjustment hardware for threshold clearance.

Baseplate and Dogging Assembly

The baseplate assembly contains the dogging components that hold the push bar depressed during business hours. These parts wear most quickly on high-traffic doors with frequent dogging use.

Springs and Pins

How to Order Von Duprin 9847 Parts Without a Return

Three pieces of information are required before placing any 9847 CVR parts order. Getting any one of these wrong produces a part that does not fit the installed device.

1. Confirm panic or fire exit hardware The -F suffix in the model number confirms fire exit hardware. Without -F is panic. This determines latch mounting bracket quantities (one per latch for panic, two per latch for fire), whether dogging parts apply, and which center case cover kit is correct.
2. Confirm metal door or WDC WDC is wood door concealed. If the device is in a wood door, rod kits 050582 and 050583 apply. For metal door installations, 050574 and 050575 apply. These rod kits are not interchangeable.
3. Check the manufacture date for dogging parts The manufacture date appears near the model number on the device label. For devices manufactured before August 1997, order old-style dogging replacement kit 050153. For post-1997 devices, current-spec parts 090040, 090042, and 090043 apply.
4. Confirm whether the device has CD cylinder dogging Cylinder dogging adds a mortise cylinder to the device body. If the device has a cylinder slot at the mechanism case, it is a CD variant and the dogging plug (090046) and CD actuator arm (090045) are present in the assembly. Non-CD devices do not have these components.
5. Verify door width (3-foot or 4-foot device) The push bar retrofit kit (PBKIT) and some mechanism case components are device-size specific. A 3-foot device uses different PBKIT from a 4-foot device. Measure the door width before ordering any push bar or mechanism case components.

Electric Latch Retraction Options on the Von Duprin 9847

The Von Duprin 9847 CVR exit device supports electric latch retraction (EL) and hex dogging with electric latch retraction (HD-EL) as field-installable additions. These options convert a mechanical 9847 device to provide remote latch retraction capability, allowing an access control system to release the latch without anyone pressing the push bar.

EL is available on panic versions only. It is not available on fire-rated 9847-F devices. When an EL-equipped 9847 receives a credential signal, a solenoid retracts the CVR latches simultaneously, releasing the door. The HD-EL version adds hex dogging capability to the electrified device, allowing the push bar to be dogged in the depressed position independently of the EL function.

The EL9847 and HD-EL9847 designations identify electrically modified versions of the original 9847 model. The current EL kit adds a solenoid module to the existing mechanical device without requiring replacement of the device body. For access control integration on 9847 CVR devices, browse Von Duprin electric strike parts for the frame-side components that work alongside EL-equipped exit devices, and see the Von Duprin QEL vs MEL guide for a comparison of electric latch retraction options across the 98/99 series.

The RX (request to exit) switch option is also available on the 9847 series. RX places a switch in the push bar that signals the access control panel when egress is initiated, preventing false alarms on the secured entry side. The LX (latch bolt monitor) option signals the panel when the latch is not properly engaged, which is required on fire doors with latch compliance monitoring under the inspection program.

CVR vs Rim vs SVR: Where the 9847 Fits in the Von Duprin Lineup

Understanding which configuration applies to your opening prevents ordering the wrong device series entirely. The three main configurations in the 98/99 series serve different door types and architectural situations.

The rim device (98 and 99 series) mounts on the door face and latches at a single frame-side strike. It is the most common configuration for single doors and paired doors with a center mullion. For a complete guide to rim exit device components and configurations, see the rim exit devices guide at SecurityParts.com.

The surface vertical rod (SVR) device uses top and bottom engagement rods that run on the door face, providing three-point locking for double doors without a center mullion. Unlike the CVR, the SVR rods are visible on the door face. The SVR is specified where concealed rods are not required but three-point locking is still needed.

The concealed vertical rod (CVR) device, which is the 9847/9947, hides the rods inside the door stile. It is the architectural choice for double doors where surface rod hardware is not acceptable and three-point locking is required. For a broader overview of the full Von Duprin series and which configuration fits which application, see the Von Duprin exit device series comparison.

NFPA 80 and Code Compliance on the Von Duprin 9847 Fire Device

The Von Duprin 9847-F fire exit hardware version must meet specific requirements under NFPA 80 that go beyond what applies to the panic version of the same device. Facility managers and locksmiths maintaining fire-rated CVR devices need to understand these requirements before performing any maintenance or parts replacement.

Positive Latching on Every Cycle

A fire-rated 9847-F device must positively latch at both the top and bottom strike on every door close, without assistance. After replacing any latch component on a fire device, test the door by releasing it from fully open without pushing or assisting the close. Both latch bolts must engage the strike fully. A top or bottom latch that does not fully engage after parts replacement is a NFPA 80 deficiency.

No Dogging on Fire Devices

NFPA 80 Section 4.7.1 prohibits any device that holds a fire door open in a manner not connected to the fire alarm system. Mechanical dogging, including hex dogging and cylinder dogging, cannot be installed on a fire-rated 9847-F device. If a 9847-F device in your facility has a hex dogging mechanism installed, it is a fire code violation that will be cited on the next NFPA 80 annual fire door inspection. For general guidance on commercial door hardware and code compliance, see the panic hardware for commercial doors guide.

Parts Replacement and UL Listing Integrity

Only OEM replacement parts maintain the UL fire listing on the 9847-F device. Aftermarket latch kits, rod assemblies, or center case components installed on a fire-rated device can void the UL listing and create liability on the next fire door inspection. For the full case for OEM parts on fire-rated hardware, see the OEM vs aftermarket commercial door hardware parts guide.

SecurityParts.com stocks commercial deadbolts and mortise locks equipped with thumbturn cylinders across multiple Schlage product lines. Browse the commercial deadbolts catalog, the commercial mortise locks catalog, and the complete Schlage hardware parts catalog. For parts identification, call 845-935-0301 or visit the SecurityParts.com contact page.

What Is a Thumbturn Cylinder?

A thumbturn cylinder is the interior actuator component on a single-cylinder deadbolt or mortise lock that allows the occupant to operate the deadbolt from the inside without a key. The user grips a small wing- or oval-shaped knob, called the thumbturn, and rotates it to throw or retract the deadbolt. On the exterior side of the door, a standard keyed cylinder provides key-controlled entry.

The term "thumbturn cylinder" describes the complete interior assembly including the thumbturn knob, the housing or escutcheon that holds it, and the internal tailpiece or cam that transmits rotation to the lock mechanism. In deadbolt hardware, this interior assembly is a separate component from the exterior key cylinder. In mortise locks, both the exterior key cylinder and the interior thumbturn are independent components that mount into the mortise case from the door face.

Schlage commercial deadbolts and mortise locks with thumbturn cylinder configurations at SecurityParts.com

 

How a Thumbturn Cylinder Works

Inside the deadbolt or mortise lock case, a cam or tailpiece extends from the back of the lock cylinder. When the keyed exterior cylinder is turned with a key, the cam rotates and drives the deadbolt mechanism. When the thumbturn interior cylinder is rotated by hand, the same mechanism is driven from the opposite side through a separate internal linkage.

The thumbturn and exterior key cylinder are mechanically independent. Turning the thumbturn does not affect the exterior cylinder, and vice versa. This independent operation is what makes the single-cylinder configuration the standard for most commercial interior and exterior openings: occupants can lock or unlock from the inside at any time, while outside entry always requires a key.

How the Thumbturn Cylinder Differs From the Key Cylinder

A key cylinder requires a correctly cut key to operate. A thumbturn cylinder requires only a hand. The two components occupy the same position in the lock assembly but on opposite sides of the door. In most single-cylinder deadbolts, the key cylinder sits on the exterior rose or escutcheon and the thumbturn sits on the interior rose or escutcheon. In mortise locks, both cylinders thread into the mortise case body and are held in place by set screws.

The cam or tailpiece on the back of a thumbturn cylinder is typically identical to the cam on the key cylinder it pairs with. Both engage the same internal mechanism from their respective sides. The difference is only in how the operator interface works: cut-key versus hand rotation.

Single Cylinder vs Double Cylinder: When to Use Each

The choice between a single-cylinder deadbolt (thumbturn inside, key outside) and a double-cylinder deadbolt (key on both sides) is one of the most consequential decisions in commercial door hardware specification. Getting it wrong creates either a security vulnerability or a life-safety hazard.

When IBC Section 1010 Permits Double Cylinder

IBC Section 1010.2.4 permits a double-cylinder deadbolt specifically when the opening is located within 40 inches of a panel of glass that could be broken to reach the interior thumbturn. The reasoning is that a thumbturn in that position creates a reach-through vulnerability: an intruder breaks the adjacent glass, extends an arm through the opening, and rotates the thumbturn to unlock the door from the outside.

Even when double cylinder is permitted, the authority having jurisdiction must approve the specification. The interior key must be kept immediately accessible to occupants, typically on a hook adjacent to the door. Double cylinder is never appropriate on a fire-rated egress door without specific approval from the local fire marshal, because NFPA 80 requires that fire doors open freely for egress.

The Reach-Through Risk and How to Mitigate It

The reach-through security risk applies when a thumbturn cylinder is installed on a door with breakable glass within arm's reach of the interior thumbturn. The four commercial mitigation strategies, in order of frequency of use, are:

1. Double-cylinder deadbolt on openings where IBC and the AHJ permit it, with interior key maintained accessible
2. Impact-resistant or laminated security glazing that holds together when struck and prevents arm entry through the opening
3. Electronic access control replacing the deadbolt entirely so the interior device is a push-button or request-to-exit switch, not a thumbturn
4. Relocating the lock to a position on the door or frame that is not reachable through the adjacent glass

Thumbturn Cylinder vs Coin Turn: Which to Specify

Schlage L Series mortise lock supports both thumbturn and coin turn interior cylinder configurations

 

A thumbturn and a coin turn perform the same mechanical function inside the deadbolt or mortise lock. The difference is entirely in how the user interface works. A thumbturn rotates easily with two fingers. A coin turn is a flat disc with a slotted face that requires a coin, a flathead screwdriver, or a proprietary tool to operate.

When to Specify a Coin Turn

Coin turns are specified in commercial and institutional settings where staff-only interior control is required without issuing keys to every occupant. The tool-requirement limits who can operate the lock from the inside without authorization. Common applications include:

• Patient room doors in behavioral health and psychiatric facilities where a patient operating a thumbturn from the inside without staff knowledge creates a safety concern
• Storeroom and secure-area doors where staff need to lock a door from the inside temporarily without issuing a key to every person who uses the room
• Accessible toilet room privacy locks in healthcare facilities, replacing a standard thumbturn to prevent patients from accidentally locking themselves in
• Server room and IT room doors where the interior control should require a deliberate tool-assisted operation rather than a casual thumbturn rotation

Coin Turn in the Mortise Lock Function Code

On Schlage L Series and other commercial mortise locks, the coin turn is available as an alternative to the thumbturn on specific function codes. In function codes where the interior cylinder controls the deadbolt or locks the outside trim, a coin turn can be specified in place of a thumbturn. The mortise case mechanism is identical. Only the interior interface component changes. Specify the coin turn at the hardware schedule stage, before the lock body is ordered, because field-converting a thumbturn mortise to a coin turn configuration requires the correct interior trim components for that specific function code.

Thumbturn Cylinder in Commercial Mortise Lock Function Codes

In commercial mortise locks, the thumbturn cylinder does not always perform the same function. The ANSI function code determines exactly what the thumbturn controls at each opening. Understanding this is essential for correct specification, because the wrong function code produces the wrong door behavior regardless of how the thumbturn itself is installed.

Schlage MA Series commercial mortise lock at SecurityParts.com available in ANSI function codes with thumbturn interior cylinder

 

• F02
  PrivacyThumbturn throws and retracts the deadbolt from inside. Outside has emergency release only. Used on restrooms, single-occupancy offices, dressing rooms.
• F04
  Entrance / OfficeThumbturn locks or unlocks the outside lever trim from the inside without a key. Inside lever always free. Used on office suite entry doors, retail entry doors.
• F09
  ApartmentKey inside required to control outside trim. Inside lever always free for egress. Thumbturn not the standard actuator coin turn or key cylinder inside. Used on apartment and dormitory entry doors.
• F13
  Hotel / ApartmentInside lever controls both deadbolt and latch. Thumbturn on the keyed side shows an occupied indicator. Outside always requires key. Used on hotel rooms, dormitories.
• F15
  Hotel / MotelThumbturn controls deadbolt from inside with occupied indicator visible from outside. Outside lever always key-operated. Used on hotel and motel room doors where room status needs to be visible from the corridor.
• F07
  StoreroomNo thumbturn on interior inside lever always free for egress, outside lever always locked and requires key. Used on storage rooms, server rooms, mechanical rooms.

For a complete guide to Schlage L Series mortise lock parts and function diagrams, see the Schlage L Series mortise lock parts diagrams. For mortise lock parts identification across all models, see the commercial mortise lock parts guide at SecurityParts.com.

Thumbturn Cylinder in Commercial Deadbolts

In commercial deadbolts, the thumbturn cylinder has a simpler and more consistent role than in mortise locks. The thumbturn throws or retracts the deadbolt. That is its only function. The exterior key cylinder performs the same operation from the outside. Together, the two cylinders give the occupant and the authorized key-holder independent control over the same bolt.

Schlage B Series Deadbolts and Thumbturn Cylinder Options

The Schlage B Series is the most widely specified single-cylinder commercial deadbolt line in the United States. Every single-cylinder model in the B Series includes a thumbturn on the interior side. The thumbturn on B Series deadbolts is a fixed-wing style that rotates 90 degrees to throw or retract the 1-inch deadbolt. The thumbturn assembly is part of the interior rose and tailpiece assembly.

Single-cylinder B Series models include the B250, B350, B360, B460, and related configurations. Double-cylinder models (no thumbturn, key on both sides) include the B252, B352, and related double-cylinder configurations. When ordering Schlage B Series hardware, confirm the correct configuration by identifying whether the model number suffix indicates single cylinder or double cylinder.

For complete parts identification on Schlage B Series deadbolts including thumbturn assemblies, interior roses, and tailpieces, see the Schlage B Series deadbolt parts guide. For visual component identification, see the Schlage deadbolt diagram. Browse the complete commercial deadbolts catalog at SecurityParts.com.

Thumbturn Cylinder in Cylindrical Locks

Cylindrical locks generally do not include a standalone thumbturn cylinder. The interior actuator on cylindrical privacy locks is a push-button or turn-button integrated into the interior lever or knob escutcheon. This is mechanically different from the thumbturn assembly found on deadbolts and mortise locks. In cylindrical lock terminology, the interior button activates a locking pin inside the lock body, not a separate cylinder cam. The thumbturn configuration in the commercial hardware context specifically refers to the mortise cylinder or deadbolt configuration, not the interior button on a cylindrical lock.

For cylindrical lock parts including interior button assemblies and lever trim, see the cylindrical locks catalog at SecurityParts.com.

Thumbturn Cylinder in Exit Device Outside Trim

Exit devices (panic bars) can be specified with an outside trim cylinder that includes a thumbturn on the interior side of the trim plate. This configuration is less common than a standard keyed outside trim, but it is specified on openings where the door must be locked and unlocked from the inside without a key, while still requiring a key for outside entry.

On Von Duprin and Falcon exit devices, outside trim options include rim cylinders, mortise cylinders, and thumbturn-equipped trim plates for specific functions. The thumbturn in this context operates the exit device's outside trim mechanism, not the push bar or latch retraction. The push bar always operates freely for egress regardless of how the outside trim is configured.

For Von Duprin exit device trim options and outside cylinder configurations, see the Von Duprin parts and series catalog. For Falcon exit device trim options, see the Falcon hardware catalog at SecurityParts.com.

How to Identify a Thumbturn Cylinder That Needs Service or Replacement

Thumbturn cylinders fail gradually in most cases, giving identifiable symptoms before they stop functioning entirely. Identifying the failure mode determines whether the fix is lubrication, adjustment, or replacement.

• Thumbturn is stiff and requires significant force
  Worn internal components, corrosion inside the cylinder, or door misalignment putting lateral stress on the thumbturn assembly. Try dry graphite or dry PTFE lubricant first. If stiffness persists, check door alignment before replacing the thumbturn.
• Thumbturn rotates but bolt does not move consistently
  Worn or damaged cam or tailpiece connection between the thumbturn cylinder and the bolt mechanism. The cam has lost its positive engagement with the lock mechanism. Replace the thumbturn assembly or the cam.
• Thumbturn spins freely with no resistance
  Stripped cam, broken tailpiece, or disconnected internal linkage. The thumbturn is completely disengaged from the bolt mechanism. Replacement of the thumbturn assembly or the complete interior cylinder is required.
• Thumbturn requires more than one full rotation to move the bolt
  Cam slippage or worn spline engagement between the thumbturn and the lock spindle. The cam is no longer positively keying to the spindle and is rotating past the engagement point before driving the bolt.
• Thumbturn is loose and wiggles laterally
  Loose mounting screws on the interior rose or escutcheon, or a worn interior spindle bearing. Tighten the interior rose screws first. If looseness persists after tightening, the interior housing has worn and the assembly needs replacement.

Thumbturn Cylinder Maintenance Best Practices

A thumbturn cylinder in a well-maintained commercial lock should operate smoothly for the full cycle life of the lock body. Most thumbturn failures on high-cycle commercial openings are caused by deferred maintenance rather than inherent component wear. Incorporating thumbturn inspection into the standard door hardware maintenance schedule prevents the majority of field failures.

• Test the thumbturn operation at every scheduled hardware inspection. Rotate through the full throw and retract arc and note any stiffness, inconsistency, or looseness. Catching early wear symptoms prevents a complete failure that leaves a door unable to lock.
• Inspect the cam engagement by removing the interior rose and observing the cam on the back of the thumbturn cylinder. The cam should engage the lock mechanism positively with no slippage at the start of rotation. A cam that requires significant rotation before engaging is worn.
• Check the interior rose screws for tightness at every inspection. Loose rose screws allow the interior housing to shift, which changes the cam alignment and eventually produces thumbturn slippage symptoms.
• On exterior-facing doors and doors in high-humidity environments such as laundry rooms, pool areas, and food service kitchens, increase inspection frequency. Moisture accelerates corrosion inside the thumbturn cylinder housing and at the cam interface.
• On high-traffic commercial openings, thumbturn cylinder service life is typically 5 to 10 years depending on traffic volume and maintenance frequency. Plan for proactive replacement rather than waiting for failure on any door that cannot be taken out of service quickly.

For a complete commercial door hardware maintenance schedule covering all hardware categories including deadbolts and mortise locks, see the commercial door hardware maintenance checklist at SecurityParts.com. For parts identification on deadbolts and mortise locks, see the deadbolt parts guide and the mortise lock parts guide.

This thumbturn cylinder guide is maintained by the commercial door hardware team at SecurityParts.com. For parts identification on Schlage deadbolts and mortise locks with thumbturn configurations, call 845-935-0301 or browse the commercial deadbolts catalog and the commercial mortise locks catalog at SecurityParts.com.

Finish codes appear on every hardware schedule and every product order. They determine whether replacement hardware matches existing hardware, whether the finish is appropriate for the environment, and whether the warranty is valid after installation. Ordering the wrong finish code produces a visible mismatch on the opening. Installing an interior-rated finish on an exterior application voids the manufacturer warranty. Getting finish selection right at the order stage prevents both problems.

Browse SecurityParts.com hardware by finish: Von Duprin exit devices in US32D, US26D, US28, and US10B; Schlage ND Series cylindrical locks in all standard finishes; Schlage L Series mortise locks by finish; LCN 4040XP closers in painted finish codes; and the complete Allegion hardware catalog. Call 845-935-0301 or visit the SecurityParts.com contact page for finish matching and 316-grade availability support.

How the US Finish Code and BHMA Code Systems Work Together

The ANSI/BHMA A156.18 standard governs materials and finishes for all commercial door hardware. It establishes finish code numbers, descriptions, base materials, and corrosion resistance test requirements. The standard maintains both the legacy US finish code system and the current BHMA three-digit system because both remain in active use throughout the industry.

Hardware schedules written by architects often use US codes because they are more descriptive and recognized by facility managers. Product catalogs from manufacturers typically list the BHMA three-digit code because it is the current ANSI-designated system. When a hardware schedule specifies US32D and a product catalog lists 630, they describe the same finish. Confirm which code system the manufacturer uses for that product line before ordering to avoid receiving the wrong finish. For a deeper look at how ANSI/BHMA standards govern all commercial hardware categories, see the ANSI/BHMA door hardware standards guide.

The Dual System Cross-Reference

Most major commercial finish codes map directly between the two systems. US26D equals BHMA 626. US32D equals BHMA 630. US3 equals BHMA 605. US10B equals BHMA 613. The letter suffix D in a US code indicates a satin (dull, brushed) texture. A code without a D suffix (US26, US32) indicates a bright (polished, mirror) texture. BHMA codes use separate code numbers for satin and bright versions rather than a letter suffix.

US32D vs US26D: The Most Important Finish Decision in Commercial Hardware

This comparison drives more finish specification errors and more warranty denials than any other finish decision in commercial hardware. The two finishes appear visually similar at installation: both are brushed, silver-toned, and non-reflective. The operational difference is fundamental and determines whether the hardware lasts its full service life or fails early.

Complete Commercial Finish Reference: Every Major US and BHMA Code

304 vs 316 Stainless Steel: When Standard US32D Is Not Enough

Both 304 and 316 stainless steel carry the US32D/630 finish designation under ANSI A156.18 because both produce an identical satin stainless appearance. The designation does not specify the grade. For most inland commercial applications, 304 stainless provides completely adequate corrosion resistance. In coastal and marine environments, the grade distinction becomes critical.

The Chloride Ion Problem

304 stainless steel is susceptible to pitting corrosion when exposed to chloride ions in concentrations found in salt air near coastlines. The chromium oxide passive layer that gives stainless steel its corrosion resistance breaks down locally under sustained chloride exposure, producing small, dark pitting marks on the surface.

316 stainless steel adds 2 to 3 percent molybdenum to the alloy, which dramatically increases resistance to chloride-ion pitting. Molybdenum stabilizes the passive layer against chloride attack. This makes 316 the correct specification for coastal and marine environments.

When to Specify 316-Grade Stainless

Specify 316-grade stainless explicitly, as a separate notation in the hardware schedule beyond just US32D, for any of the following:

• Any opening within approximately three miles of saltwater shoreline, including ocean, bay, tidal river, or inlet
• Marine and waterfront environments regardless of the exact distance measurement
• Buildings with indoor swimming pools where chlorinated water vapor is present in the air
• Food-processing environments using salt brine or other chloride-containing processing fluids

Environment-Specific Finish Recommendations

How to Match Finishes Across a Complete Door Opening

A complete commercial door opening includes multiple hardware components from potentially different manufacturers: a lockset or exit device, a door closer, hinges, and possibly a kickplate, push plate, pull bar, or door viewer. All visible hardware in a single opening should match in finish tone. Mismatches are visible and are typically cited as non-conformance during punch list inspections.

LCN Door Closer Painted Finish Codes

Door closers present a unique matching challenge. The complex body geometry of a door closer makes uniform plating impractical and expensive. Industry convention specifies door closers in painted finishes that complement the lockset and exit device finish rather than exactly matching the plated finish.

LCN 4040XP Series painted finish codes: 689 is painted aluminum (silver-toned, pairs with US26D and US28 hardware); 690 is painted dark bronze (pairs with US10B and US10 trim); 691 is painted light bronze (pairs with US10B and similar bronze-toned trim). When specifying a complete opening, list the closer finish as 689, 690, or 691 depending on the lockset finish, not as a US code.

Von Duprin Exit Device Finish Codes

Von Duprin uses a combined finish designation on exit device orders. Common codes: US32D or 630 for satin stainless; US26D or 626 for satin chrome; US28 or 628 for satin aluminum on aluminum exit device configurations; US10B or 613 for oil-rubbed bronze on trim components. The mechanism case of most Von Duprin rim devices ships in painted aluminum or steel regardless of the ordered finish code: the finish code applies primarily to the latch, strike, and trim components.

Browse Von Duprin exit device parts by series and Von Duprin electric strike parts in US32D and US26D at SecurityParts.com.

Schlage Hardware Finish Availability

Schlage ND Series cylindrical locks and Schlage L Series mortise locks are available in all standard US and BHMA finish codes including US26D, US32D, US10B, and US28. Not every function code is available in every finish within every series. Confirm finish availability for the specific function code before finalizing a project hardware schedule.

How to Read Finish Codes on a Commercial Hardware Schedule

Hardware schedules list finish codes in a standardized column format. Reading this column correctly prevents ordering errors that cause finish mismatches and punch list delays.

1. Identify which code system the schedule uses Some schedules use US codes (US26D), some use BHMA codes (626), and some use both. Identify the system in the schedule legend or general notes before reading individual line items.
2. Cross-reference to the product catalog system If the schedule uses US codes and the manufacturer catalog uses BHMA codes, translate before ordering. US26D equals 626. US32D equals 630. Do not assume the codes transfer without verification.
3. Check for 316-grade stainless callouts A schedule that lists US32D or 630 without an explicit 316-grade notation defaults to 304 stainless. If the project is in a coastal, pool, or high-chloride environment, look for supplementary spec language and clarify with the specifier before ordering if it is absent.
4. Verify finish availability for each line item Not every hardware product is available in every finish. A schedule that specifies US32D for all hardware may have line items where the specified product is only available in US26D in that series. Identify exceptions before issuing purchase orders.
5. Confirm closer finish separately Door closers are listed with painted finish codes (689, 690, 691) rather than US codes. If a US code appears in the closer line, contact the manufacturer to confirm the intended painted finish equivalent.

For a complete guide to commercial door hardware standards and ANSI/BHMA certification grades, refer to the ANSI/BHMA standards guide linked in the opening section of this blog. For hardware maintenance intervals by finish type, see the commercial door hardware maintenance checklist. For guidance on choosing between OEM and aftermarket replacement parts in any finish, see the OEM vs aftermarket commercial door hardware parts guide.

When you install a door closer on a commercial door correctly, it lasts through its rated cycle life. When installed incorrectly, it fails within months regardless of brand or quality. SecurityParts.com stocks LCN door closer parts and complete units for every commercial mounting configuration. Browse the LCN door closer parts catalog, the LCN commercial door closer selection guide, and the complete LCN brand parts catalog. Call 845-935-0301 or visit the SecurityParts.com contact page for pre-installation parts identification support.

How to Install Door Closer on Commercial Door: Key Facts Before You Begin

Installing a door closer on a commercial door correctly determines whether the device lasts through its full rated cycle life or fails within months. A commercial door closer is a hydraulic-mechanical device that controls the speed and force at which a door closes after being opened. Inside the housing, a compressed spring stores energy when the door opens. Hydraulic fluid flowing through calibrated passages governs how quickly the spring returns the door to the closed position. The result is a controlled, consistent closing arc on every cycle.

Incorrect installation of a door closer on a commercial door is one of the most common causes of premature closer failure, arm damage, and ADA non-compliance. A closer mounted in the wrong position, with the arm shoe set incorrectly, or with the wrong spring size for the door will not perform correctly regardless of how carefully the valves are adjusted afterward. Getting the physical mounting right from the start is what determines whether the closer lasts through its rated cycle life or fails prematurely.

For an overview of closer types including surface-mounted, overhead concealed, and floor spring models, see the commercial door closers types guide at SecurityParts.com before selecting the closer for your application.

Tools Required Before You Begin

Safety Precautions

• Never work alone on a heavy commercial door. A second person should control the door while you drill and mount hardware.

• On fire-rated doors, confirm with the authority having jurisdiction before beginning. Drilling non-approved holes can void the door's fire rating.

• Use a center punch on all metal door surfaces before drilling. Metal door faces deflect drill bits and produce misaligned holes.

• Do not over-torque the mounting screws. Stripped screws in hollow metal doors are a common and difficult problem to correct after installation.

• Keep the spring power dial or power adjustment at the factory default setting during initial installation. Set the final spring size only after the arm is attached and the door is cycling.

The Three Surface-Mounted Arm Configurations

Before touching the installation template, identify which arm configuration applies to your opening. The three configurations are not interchangeable, and using the wrong one changes which face of the door and frame the closer body mounts to, which side the arm shoe bracket goes on, and which template column to use.

LCN 1000 Series surface mounted closers at SecurityParts.com available in regular arm, parallel arm, and top jamb configurations

 

Reading and Using the LCN Installation Template

The LCN installation template is a paper guide that ships inside the box with every new LCN closer. It is the most important tool in the installation process and the step that most field errors trace back to when skipped.

What the Template Shows

The template has separate columns for regular arm, parallel arm, and top jamb configurations. Each column shows the exact hole locations for both the closer body mounting holes and the arm shoe bracket holes relative to the door top edge and the door face. The template also shows the backset columns (the horizontal distance from the door edge to the latch bolt center) so the arm shoe is positioned correctly relative to the latch.

Step-by-Step Template Usage

Determine the correct template column Identify your arm configuration (regular, parallel, or top jamb). On the template, locate the column header for that configuration. If the door swings right (hinge on left), use the right-hand column. Left-swing doors use the left-hand column. Most LCN templates mark this clearly with an arrow and "Hinge Side" indicator.

Mark the centerline height on the door Most commercial installations place the closer centerline 1 inch from the door stop rabbet on the pull side. Measure from the top of the door down to this height and mark a horizontal line across the full door face with a pencil. This line is your alignment reference for the template.

Align the template fold line with the door top edge The template has a fold line or cut line that aligns with the top edge of the door. Fold the template along this line and position it so the fold sits at the door top edge and the template face lies flat against the door face. The centerline mark on the template should align with your pencil line.

Tape the template in place Use masking tape at all four corners. Verify the template has not shifted or bubbled before marking holes. A shifted template produces holes that are off by several millimeters, which changes the arm geometry at final installation.

Mark all hole centers with an awl or center punch On hollow metal doors, use a center punch and a single hammer tap to mark each hole center. This creates a small dimple that keeps the drill bit from walking across the metal surface. On wood doors, a sharp awl is sufficient. Mark every hole in the template before removing it.

Remove the template and drill all holes Use the correct bit size for the mounting screws supplied with the closer. For most LCN closers on hollow metal doors, this is a 7/32-inch bit. Drill straight through the door face only. Do not drill through the full door thickness unless instructed.

How to Install a Door Closer on a Commercial Door: Regular Arm

Regular arm is the most common configuration for interior commercial doors. The closer body mounts on the pull side of the door face, and the arm extends from the body to a shoe bracket mounted on the frame.

LCN 4000 Series surface mounted closers including the 4040XP at SecurityParts.com

 

Mount the closer body to the door face Position the closer body over the drilled holes on the pull side of the door. Insert the mounting screws by hand first to confirm alignment, then drive them with a screwdriver. Do not use an impact driver. The screw seats are in lightweight hollow metal and strip easily under impact torque. Snug is correct. The body should sit flat against the door face with no rocking.

Confirm the spindle is in the correct position On the LCN 4040XP, the closer spindle (the shaft that the arm attaches to) should point toward the hinge side of the door. Verify this before attaching the arm. If the spindle points toward the latch side, the closer was mounted in the wrong orientation and will bind through the closing arc.

Close and fully seat the backcheck valve Turn the B valve fully clockwise before attaching the arm. This prevents the door from swinging open without resistance during the next step.

Attach the main arm to the spindle Slide the main arm onto the closer spindle. The arm should engage the splined or keyed spindle shaft securely. Insert the pinch bolt and tighten finger-tight only. Do not fully tighten yet. You may need to rotate the arm slightly during the next step to align the shoe bracket holes.

Mount the shoe bracket on the frame Hold the door at 90 degrees open (have your second person hold the door). Position the shoe bracket on the frame at the hole locations marked by the template. Insert and drive the shoe bracket screws fully. Frame mounting screws go through the door stop into the hollow metal frame. Use all provided screws.

Connect the forearm to the shoe bracket With the door held at 90 degrees, connect the forearm end of the arm assembly to the shoe bracket. Insert the connecting pin or bolt, and tighten. Now tighten the pinch bolt at the spindle connection. The arm should feel rigid with no lateral play.

Test the arm through the full arc before valve adjustment Slowly open the door to full extension and allow it to close freely. Watch the arm through the full arc. The arm should move smoothly with no binding, scraping, or sharp changes in resistance (other than the backcheck engaging at approximately 70 to 75 degrees). If the arm binds at any point, stop and check the geometry before proceeding to valve adjustment.

How to Install a Door Closer: Parallel Arm Configuration

Parallel arm places the closer body on the push side of the door. The arm runs parallel to the door top rail when the door is closed, which keeps the arm below the sight line and reduces exposure to deliberate damage.

Mount the closer body on the push side of the door Drill holes per the parallel arm column of the template. Mount the closer body on the push face of the door with the spindle pointing toward the hinge side. On the parallel arm configuration, the body position is farther from the latch edge than on a regular arm installation, per the template dimensions.

Mount the parallel arm bracket on the frame push side The parallel arm uses a two-piece bracket system: a main bracket on the frame head and an adjustable shoe. Mount the frame bracket at the hole locations from the parallel arm column of the template. The bracket mounts on the frame push side at the same elevation as the closer body.

Confirm backcheck valve is closed Turn the B valve fully clockwise before attaching the arm.

Attach the arm to the spindle The parallel arm assembly is slightly different from the regular arm: the main arm attaches to the spindle and runs back toward the hinge side when the door is closed. Insert the spindle connector and snug the pinch bolt.

Connect the forearm to the frame bracket With the door held at 90 degrees, connect the forearm to the frame bracket through the shoe. Adjust the shoe position along the frame bracket slot so the arm is under slight tension in the closed position without being overtightened. Tighten the shoe set screw and the pinch bolt.

Verify arm does not contact the door stop when closing Slowly close the door from 90 degrees and watch the arm clearance as the door reaches the frame. The arm must not contact the door stop or frame extrusion at any point in the arc. If it does, adjust the shoe position slightly toward the hinge side and retest.

How to Install a Door Closer: Top Jamb Configuration

Top jamb is required on aluminum storefront doors and any opening where there is no accessible door surface on the pull side for closer body mounting. The body mounts on the frame head, not the door.

When a Soffit Plate Is Required

On aluminum extrusion frames, the frame head surface is often a narrow extrusion that does not provide a flat mounting surface matching the closer body hole pattern. A soffit plate (also called a mounting plate) attaches to the frame head first, distributing the closer mounting load across the extrusion. Without it, the mounting screws pull through the thin aluminum extrusion under the repeated load of each door cycle.

Check whether your frame head is a standard hollow metal section (minimum 1/16-inch wall thickness) or an aluminum extrusion. Aluminum extrusions almost always require a soffit plate. Hollow metal sections typically do not.

Mount the soffit plate if required If the frame head is an aluminum extrusion, mount the soffit plate to the frame head first using self-tapping screws into the extrusion at the template-specified locations. The soffit plate creates the flat mounting surface the closer body needs.

Mount the closer body to the frame head (or soffit plate) Position the closer body on the frame head per the top jamb column of the template. The spindle should point downward toward the door on the pull side. Drive all mounting screws fully. On hollow metal frames, these screws go through the frame head into the frame interior.

Mount the arm shoe bracket on the door top rail The arm shoe for top jamb mounts on the door top rail on the pull side. Drill per the template hole locations. Drive all shoe bracket screws fully into the door top rail.

Close the backcheck valve before arm attachment Turn the B valve fully clockwise.

Attach the arm assembly from spindle to shoe With the door held at 90 degrees, connect the arm from the closer spindle down to the door top rail shoe bracket. Insert the connecting hardware and tighten. The arm should be under slight tension with the door in the 90-degree open position.

Test the arm for clearance through the full arc Close the door slowly and confirm the arm clears all frame geometry through the full closing arc. Top jamb arms can contact the frame head stop if the arm is too long or the shoe position is too far from the hinge side.

Arm Adjustment After Mounting

Checking Arm Geometry

Before adjusting any valves, check that the arm geometry is correct. Open the door to 90 degrees and look at the arm from above. At 90 degrees, the main arm and the forearm should form approximately a 90-degree angle between them. If the arm is near-straight (less than a 90-degree angle between the two arm segments) at 90 degrees open, the shoe is too close to the hinge side. If the angle is very acute (more than 90 degrees), the shoe is too far from the hinge side.

Incorrect arm geometry at 90 degrees produces inconsistent closing behavior and accelerated wear at the arm pivot. The template dimensions prevent this when followed correctly. If the geometry is off, reposition the shoe bracket before proceeding.

Arm Connection Tightening Sequence

After geometry is confirmed correct, fully tighten all arm connections in this sequence: the shoe bracket screws in the frame or door first, then the forearm-to-shoe connection, then the pinch bolt at the spindle. This sequence prevents a loose frame bracket from causing the arm to shift during pinch bolt tightening.

Spring Power Adjustment

Spring power determines how much force the closer exerts to close the door. Too little spring power and the door stalls before latching. Too much and the door exceeds the ADA 5-pound opening force limit.

LCN 4040XP External Spring Power Adjustment

The LCN 4040XP uses an external spring power adjustment dial, also called the LCN Green Dial, on the spring tube. This allows spring power adjustment without removing the closer from the door or disassembling the unit. The dial has numbered positions from 1 (minimum) through 6 (maximum). To increase spring power, turn the dial clockwise. To reduce it, turn counterclockwise. Start at position 3 or 4 for a standard 3-foot interior door and adjust from there based on performance testing.

Spring Sizes on Other LCN Models

On LCN 1000 Series and other models without an external dial, spring power is determined by which spring the unit ships with. These closers come in sizes 1 through 6, and changing the spring size requires replacing the spring assembly inside the closer body. For most commercial door applications, ordering the closer in the correct spring size from the outset is more practical than field-swapping springs.

For specific parts for each LCN series including spring assemblies, arms, and mounting hardware, see the LCN 1000 Series door closer parts guide and the LCN 4000 Series door closer parts guide at SecurityParts.com.

Hydraulic Valve Adjustment After Installation

Once the arm is connected and the spring power is set, the three hydraulic valves need field adjustment to match the actual door conditions. All three valves are adjusted with a 3/32-inch hex key. Turn valves clockwise to restrict fluid flow and slow that phase of the closing arc. Turn counterclockwise to open flow and speed that phase up. Always make adjustments in 1/8-turn increments and test multiple cycles after each change.

Setting the Sweep Speed (S Valve)

The sweep valve controls the door from fully open down to approximately 10 to 15 degrees from the frame. Set the sweep speed first since it covers the longest portion of the closing arc. Target 5 to 7 seconds from 90 degrees to the point 3 inches from the frame on ADA-accessible doors. Time this with a stopwatch. If the door slams through the sweep arc, close the S valve clockwise. If it stalls before reaching the frame, open the S valve counterclockwise.

Setting the Latch Speed (L Valve)

The latch valve controls the final degrees from approximately 10 to 15 degrees to fully closed. Set it after the sweep is correct. The door should accelerate slightly through the latch zone and seat against the strike with a clean, firm click. If it stalls in the last few degrees or bounces back from the strike, open the L valve counterclockwise. If it slams into the frame, close it clockwise. The latch speed should always be slightly faster than the sweep speed.

Setting the Backcheck (B Valve)

Set the backcheck last. With the arm now connected and the door cycling correctly, slowly swing the door open past 75 degrees and feel for the resistance point. The backcheck should engage between 70 and 80 degrees and provide clear but not excessive resistance against the door being swung further open. If there is no resistance at all, close the B valve clockwise. If the backcheck engages too early (before 70 degrees) and makes the door feel stiff through the normal opening range, open it counterclockwise slightly.

For detailed valve adjustment guidance, seasonal calibration, and brand-specific instructions, see the complete commercial door closer adjustment guide at SecurityParts.com.

ADA Compliance After Installing a Door Closer on a Commercial Door

ADA compliance on door closers has two separate measurements that both must pass on accessible routes.

Opening Force: 5-Pound Maximum

Use a door pressure gauge at the leading edge of the door (the latch side). Push or pull perpendicular to the door face and read the peak force required to start the door moving. The limit is 5 pounds for interior non-fire-rated doors on accessible routes. If the reading exceeds 5 pounds, reduce spring power. Do not try to compensate with valve settings: valves do not control opening force.

Closing Speed: 5-Second Minimum

Using a stopwatch, time the door from 90 degrees open to the point 3 inches from the door stop. Per ANSI A117.1, the door must take a minimum of 5 seconds for this arc. If it closes faster, slow the sweep valve clockwise. A door that fails this test on an accessible route is an ADA liability regardless of how well everything else was done.

Fire-Rated Door Closer Installation Requirements

Installing a door closer on a fire-rated commercial door involves requirements beyond standard closer installation. Non-compliance is discovered during NFPA 80 annual fire door inspections and can result in immediate deficiency citations.

The Closer Must Be Grade 1 and UL Listed

ANSI/BHMA A156.4 Grade 1 is the minimum standard for fire-rated door assemblies. The closer must also carry a UL listing for fire door use. A Grade 1 closer without a UL fire listing is not an acceptable specification on a fire-rated opening, even though the grade rating alone might suggest otherwise.

No Hold-Open Arms on Fire-Rated Doors

NFPA 80 Section 4.7.1 prohibits any device that holds a fire door open in a manner that is not connected to the fire alarm system. A mechanical hold-open arm or a slide track arm with a hold-open feature cannot be installed on a fire-rated door. Every fire door must close and latch automatically after each use. The only compliant hold-open solution for fire-rated doors is a fire-rated electromagnetic holder that releases when the fire alarm activates.

Closing Speed Must Latch Against Fire Door Resistance

Fire doors are typically heavier than non-rated interior doors and include intumescent seals that compress as the door closes. The closer must have enough spring power and latch speed to overcome this seal compression and produce positive latching on every cycle. After installation, test the door from a full open position by releasing it without assisting the close. The door must self-close and self-latch without manual assistance.

For fire door closer adjustment guidance specific to NFPA 80 closing speed requirements and spring size selection, see the fire door closer adjustment guide at SecurityParts.com.

Common Door Closer Installation Mistakes

• Skipping the installation template The most common cause of incorrect arm geometry and premature arm failure. The template is not optional. It determines every hole position on both the door and the frame.

• Not closing the backcheck valve before attaching the arm Opening a door with the backcheck fully open and no arm resistance can damage the closer body on the first cycle. Always seat the B valve clockwise before connecting the arm.

• Mounting in the wrong arm configuration for the opening Installing a regular arm on a push-side application or a parallel arm on a pull-side opening reverses the mechanical advantage and produces incorrect geometry through the closing arc.

• Under-torquing the arm shoe bracket screws The shoe bracket takes the full mechanical load of every closing cycle. Insufficiently tightened screws work loose under repeated cycling and allow the bracket to shift, bending the forearm arm and eventually damaging the closer spindle.

• Using the wrong spring size for the door A spring too light for the door weight causes stall-before-latch. A spring too heavy produces opening force exceeding the ADA limit. Select the spring size by door width and weight, not by default to the closest spring on hand.

• Adjusting valves on a door with incorrect arm geometry Valve adjustment cannot compensate for incorrect mounting. If the arm geometry is wrong, no combination of valve settings produces consistent closing behavior. Fix the geometry before touching the valves.

• Installing a mechanical hold-open arm on a fire-rated door A direct NFPA 80 violation that will be cited on the next fire door inspection. Fire-rated doors must close and latch automatically on every cycle.

• Skipping ADA verification after installation Installation is not complete until opening force and closing speed are measured with calibrated tools. Estimated compliance is not compliance.

Troubleshooting After Installation

• Door stalls before latching
  Open the L valve counterclockwise in 1/8-turn increments. If the door still stalls, increase spring power one size. Check that the strike and latch bolt are aligned before adjusting further.

• Door slams into the frame
  Close the L valve clockwise to slow the final arc. If slamming happens through the main arc, also close the S valve. Confirm spring size is not too large for the door.

• Arm binds or feels stiff at a point in the arc
  Stop immediately. A binding arm almost always indicates incorrect geometry. Check that the shoe bracket is at the correct template position. A binding arm puts destructive lateral load on the closer spindle.

• Opening force exceeds 5 pounds for ADA
  Reduce spring power. Valve settings do not change opening force. On LCN 4040XP, reduce the spring power dial setting. On other models, replace with a smaller spring.

• Door closes too slowly for fire door latching
  Open the L valve counterclockwise. Increase spring size if the door still cannot overcome seal compression. Verify the arm geometry is correct and the arm is not binding.

• Closer body rocks or is not flush against door
  Holes may be misaligned due to template not being held flat. Remove the closer and verify hole positions against the template. Re-drill if necessary using a longer drill guide.

• Arm shoe bracket loosens after a few days
  All frame screws were not driven fully. Remove the arm, re-drive all shoe bracket screws to full torque, and reattach the arm. Use thread-locking compound on the bracket screws if the holes are in a hollow section with minimal thread engagement.

• Door does not pull completely closed in cold weather
  Cold hydraulic fluid thickens and slows the closing arc. Seasonal valve adjustment is normal. Open the S and L valves slightly counterclockwise. If the closer uses standard (non-all-weather) hydraulic fluid, consider replacing the unit with an all-weather fluid model for exterior or temperature-exposed applications.

For broader door hardware troubleshooting beyond the closer itself, see the commercial door hardware troubleshooting guide at SecurityParts.com.

Maintenance After Installing a Door Closer on a Commercial Door

A correctly installed and adjusted commercial door closer requires minimal maintenance but does need periodic attention to stay in compliance and perform consistently.

• Inspect the arm connections and shoe bracket screws at every scheduled maintenance visit. Tighten any screws that show movement. On high-traffic doors, this should happen quarterly.

• Check closing speed with a stopwatch at the start of heating season and cooling season. Seasonal temperature changes affect hydraulic fluid viscosity and will shift valve performance. A few minutes of valve adjustment twice a year keeps the closer in spec.

• Inspect the arm pivot pins for wear. A worn or loose pivot pin produces arm rattle and changes the arm geometry subtly over time. Replace worn pivot hardware before the geometry shift damages the closer spindle.

• On exterior and vestibule closers, verify the cover plate is fully seated and undamaged. A missing or cracked cover exposes the valve ports to debris and water on exterior applications.

• Confirm ADA compliance measurements annually during fire door inspections and whenever the closer has been adjusted or the door has been re-hung.

For a complete maintenance schedule with monthly, quarterly, and annual task breakdowns, see the commercial door hardware maintenance checklist at SecurityParts.com. For door closer component identification, see the door closer parts diagram.

SecurityParts.com stocks Schlage ALX Series parts and components. Browse the Schlage ALX Series parts and diagrams, the complete Schlage hardware parts catalog, or the commercial cylindrical lock parts catalog. For parts identification support, call 845-935-0301 or visit the SecurityParts.com contact page.

Schlage ALX Series cylindrical lock Grade 2 commercial with in-field function change capability

 

What Is the Schlage ALX Series?

The Schlage ALX Series is a commercial-grade cylindrical lock designed for light-to-medium traffic openings in office, healthcare, education, and multi-family residential applications. It is rated ANSI A156.2 Grade 2, which means it meets the standard for commercial applications where Grade 1 heavy-duty performance is not required. The ALX Series replaced the Schlage AL Series as the current-generation commercial cylindrical product and carries the same fundamental door preparation dimensions, making it a direct field replacement on doors previously fitted with AL Series hardware.

The defining feature of the Schlage ALX Series is its in-field function change (IFFC) capability. The function of the lock, which determines how each side operates in relation to the other, can be changed after the lock is already mounted on the door without removing the lock body, replacing trim, or re-keying. This single capability makes the ALX Series significantly more practical than fixed-function cylindrical locks on renovation projects where tenant configurations change frequently.

Schlage ALX Series Grade and Standards

The Schlage ALX Series is certified to ANSI A156.2 Grade 2 for cylindrical and bored locks. Grade 2 requires a minimum of 250,000 operating cycles, a 450-pound static load resistance on the bolt, and 250 pounds of force resistance on the lock body. These ratings make the ALX Series appropriate for interior openings in commercial and institutional buildings where the door is used frequently but does not face the abuse-level forces of a Grade 1 application.

The ALX Series is also UL listed for use on fire-rated assemblies in specific configurations, making it suitable for interior fire-rated corridor doors in office and healthcare settings. Always confirm the UL listing of the specific function code before specifying on a fire-rated opening.

Schlage ALX Series Function Codes: Every Model Explained

Every Schlage ALX Series lock is designated by a function code that determines how the outside lever and inside lever operate independently. Understanding the function codes is the first step in both specifying the correct lock and using the in-field function change feature to move between functions after installation.

Schlage ALX Series function codes guide each lock's operation from passage to storeroom

 

• ALX10S
  Passage LatchLever always free from both sides. Latch retracts by operating either lever. No locking function. Used for interior doors that must always remain accessible such as waiting rooms and open office areas.

• ALX40
  PrivacyInside push button locks the outside lever. Outside can be unlocked with an emergency release tool (small flat tool through the outside rose pinhole). Used for single-occupancy restrooms and private offices.

• ALX44S
  Entry with Turn ButtonOutside lever is locked or unlocked by key from outside or turn button from inside. Inside lever is always free. Used for building entry doors and suite entry where key control from outside is needed.

• ALX50
  EntranceOutside lever locked or unlocked by key from outside. Inside lever always free. Key holdback from outside not available. Used on entry doors requiring key control without key holdback capability.

• ALX53
  OfficeOutside lever locked or unlocked by key from outside with key holdback. Inside lever always free. Key holdback keeps the lock unlocked for business hours without a key in the outside lever. Widely used on office suite doors.

• ALX70
  ClassroomOutside lever locked or unlocked by key from outside only. Inside lever always free. Cannot be held in the unlocked position from outside. Used on classroom and institutional corridor doors where outside access is key-only at all times.

• ALX80
  StoreroomOutside lever always locked. Entry by key from outside only. Inside lever always free for egress. Used on storage rooms, server rooms, and utility closets requiring constant key control from the outside.

• ALX170
  Single DummyTrim only, no latch or lock mechanism. One lever on one side of a door for appearance or pull function only. Used on double doors where one leaf is inactive and only a pull handle is needed.

• ALX172
  Double DummyTrim only on both sides, no latch or lock mechanism. Used where a lever appearance is needed on both sides of an inactive door leaf or a door that is not a functioning entry point.

Schlage ALX Template: Door Preparation Dimensions

The Schlage ALX template is the paper drilling guide that ships with every new Schlage ALX Series lock. It sets out the precise hole positions for the cross bore, latch bore, and edge bore so the lock body, latch, and trim align correctly after installation. Using the Schlage ALX template before drilling is the only reliable way to ensure all three holes are correctly positioned relative to each other and to the door edge.

Standard Schlage ALX Template Dimensions

How to Use the Schlage ALX Template

Measure and mark the lock centerline height Standard commercial door lock centerline is 38 inches from the finished floor. Mark this height on the door edge with a pencil line across the full door thickness.

Position the Schlage ALX template on the door face Fold the template along the door edge fold line. Align the backset marker on the template with the desired backset (2-3/4 inch for standard or 2-3/8 inch for narrow stile). Align the horizontal centerline of the template with the lock height mark on the door edge. Tape the template in place.

Mark the cross bore center Use an awl or sharp pencil to mark the cross bore center through the template. This is the center of the 2-1/8 inch hole that passes through the door face.

Mark the latch bore center on the door edge The template includes a fold line for the door edge. With the template folded around the edge, mark the latch bore center on the door edge at the intersection of the lock height line and the edge template centerline.

Drill the cross bore first Use a 2-1/8 inch hole saw. Drill from one face until the pilot bit just breaks through the opposite face, then complete the hole from the opposite face to prevent tear-out on the door face veneer.

Drill the latch bore on the door edge Use a 1 inch spade bit or forstner bit. Drill perpendicular to the door edge at the marked center. Depth should be sufficient for the full latch assembly length.

Chisel the latch faceplate mortise Score the faceplate outline on the door edge using the latch assembly as a template. Chisel the mortise to the depth of the faceplate thickness so the faceplate sits flush with the door edge surface.

Install and test before finishing Insert the latch assembly, mount the lock body, and test operation before applying any door finish or painting. Confirm the latch extends and retracts freely and the door closes and latches cleanly against the strike.

Schlage ALX Series In-Field Function Change: Step-by-Step Guide

The Schlage ALX Series in-field function change (IFFC) is the feature that makes the ALX Series a practical choice for buildings with changing tenant configurations. Instead of removing the lock, sourcing a different function unit, and reinstalling, the facility manager changes the function at the door in minutes using only the Schlage IFFC change tool.

What You Need for the In-Field Function Change

The Schlage ALX in-field function change requires only the Schlage IFFC change tool (Schlage part C415-782). No other tools are required. The lock stays on the door throughout the procedure. The function change does not affect the keying of the lock, so re-keying is not required after a function change.

In-Field Function Change Procedure

Open the door and hold it open The function change must be performed with the door open so the latch bolt is not engaged in the strike. The bolt must be in the retracted position for the mechanism to cycle freely.

Locate the IFFC change port on the inside rose The change port is a small circular opening on the inside rose or inside escutcheon. On ALX Series locks it is typically at the 6 o'clock position on the rose when the lever is in the neutral position. A small function indicator window next to the port displays the current function code.

Insert the IFFC tool into the change port Insert the tip of the C415-782 IFFC tool into the change port. Apply light inward pressure to engage the tool with the change mechanism inside.

Turn the inside lever while pressing the tool Simultaneously press the IFFC tool inward and turn the inside lever in the direction indicated by the function diagram on the template that shipped with the lock. One lever operation advances the mechanism one function position.

Check the function indicator window Release the tool and lever. Read the function code displayed in the indicator window. Repeat steps 3 and 4 until the desired function code appears.

Test both sides before closing the door Confirm the new function operates correctly from both sides of the open door before closing. For storeroom (ALX80), confirm the outside lever does not operate without a key. For passage (ALX10S), confirm both levers operate freely. Confirm the latch retracts and returns correctly.

Close and test the door in the frame Close the door and confirm the latch engages the strike cleanly. Test all functions again from both sides of the closed door to confirm the function change is complete and operating as specified.

Schlage ALX Series vs ND Series: Which to Specify

Schlage ND Series Grade 1 cylindrical lock compared to the ALX Series Grade 2 for commercial specification decisions

 

The ALX and ND Series use identical door preparation dimensions. A building that starts with ALX Series on interior offices can specify ND Series on high-traffic main corridors without requiring different door prep. Both series share the same Schlage keyways, so a single key system can cover both ALX and ND hardware throughout the building. This compatibility is one of the primary reasons the Schlage cylindrical lock product line is widely specified in mixed-use commercial projects.

Browse the complete commercial cylindrical lock parts catalog at SecurityParts.com for both ALX and ND Series parts and diagrams.

Schlage ALX Series Key and Cylinder Options

Everest Keyway

The Everest keyway is Schlage's restricted key system for the ALX Series. Everest keys are patented and cannot be duplicated at hardware stores or standard key shops without authorization from the building owner or key system manager. This key control protection is built into the key itself, not just the cylinder, making it significantly more resistant to unauthorized key copying than a standard commercial keyway.

Everest is the recommended keyway specification for new construction projects where key control is a priority and the building owner wants to maintain control over who can have keys made. For the key system management process that governs how master keys, submaster keys, and individual change keys are issued across a building, see the Schlage key systems guide at SecurityParts.com.

C Keyway

The standard C keyway is the most widely used Schlage commercial cylinder keyway and is available at most key shops. It is the correct specification for projects joining an existing C-keyway master key system, or where key duplication convenience is a priority over key control. The C keyway is compatible with the full Schlage ALX Series function range.

SFIC (Small Format Interchangeable Core)

SFIC cylinders allow the key core to be removed and replaced with a control key without disassembling the lock from the door. In SFIC buildings, the facility manager can rekey every ALX Series lock in the building in a single pass using only the control key, without calling a locksmith. SFIC compatibility is available on most ALX Series function codes and is commonly specified in healthcare and education facilities where rekeying the building must be completed quickly between tenants or following a security incident.

Schlage ALX Series OEM Replacement Parts

Schlage hardware OEM parts for ALX Series cylindrical locks at SecurityParts.com

When a Schlage ALX Series cylindrical lock requires service, the correct specification is always OEM Schlage parts. Aftermarket components are not manufactured to the ANSI A156.2 Grade 2 tolerances the ALX mechanism depends on and may produce inconsistent latch engagement, premature wear, or mechanism failure. On fire-rated openings, non-OEM parts can invalidate the UL listing of the door assembly.

Most Commonly Replaced ALX Series Parts

• Latch bolt assembly the most common mechanical replacement, worn from repeated latch-to-strike contact on misaligned doors

• Lever trim and rose worn, damaged, or finish-matched replacement on renovation projects

• Strike plate ANSI T-strike in standard or box strike configuration, replaced when damaged or when the door edge shifts from frame settlement

• Cylinder and core replacement for lost-key situations, rekeying after a security incident, or conversion to SFIC

• Spindle the connecting bar between outside and inside lever trim, occasionally bent from lever abuse

• Through-bolts stripped or missing mounting screws that cause the trim to loosen from the door face

Browse OEM Schlage ALX Series parts at the Schlage ALX Series parts and diagrams page. The interactive diagram on the product page identifies each component by its position in the assembly so you can confirm the correct part before ordering. See also the complete commercial cylindrical locks guide for specification guidance across the full Schlage cylindrical lock range.

The Von Duprin panic bar electrified options discussed in this guide are available on the series stocked at SecurityParts.com. Browse the complete Von Duprin exit device and panic bar catalog and the full Von Duprin parts and series guide. For specification support before ordering, call 845-935-0301 or visit the SecurityParts.com contact page.

Von Duprin exit device electrified options : QEL and MEL for access control integration at the panic bar level

 

What QEL and MEL Do and Why They Exist

A standard mechanical Von Duprin panic bar allows egress from the inside by pressing the push bar. It does not allow entry from the outside unless the door is equipped with a separate outside trim function (lever, knob, or thumbturn) that retracts the latch from the exterior. On openings requiring controlled outside access, the most common solution historically was an electric strike in the frame that releases on an access grant signal. That is a frame-side solution.

QEL and MEL are device-side solutions. They retract the latch bolt inside the Von Duprin panic bar itself when an access grant signal is received, instead of releasing the keeper in the frame. The door swings open under push or pull without any secondary hardware in the frame. This matters for a few reasons: it works on hollow metal frames where installing an electric strike requires a cut that voids the frame's fire rating on rated assemblies, it preserves the full security engagement of the mechanical latch during normal locked conditions, and it simplifies the overall hardware schedule on a complex opening.

The Outside Trim Question

QEL and MEL retract the latch. They do not provide a pulling handle on the outside. A Von Duprin panic bar with QEL still requires an outside trim component for the user to physically pull the door open after the latch retracts. Outside trim options include levers, knobs, pulls, and thumbturns, available in a range of functions depending on the access control integration required. The trim function is specified separately from the QEL or MEL configuration and must be compatible with the outside trim options available for the specific series.

How QEL Works vs How MEL Works

Which Von Duprin Series Support QEL and MEL

Not every Von Duprin panic bar series supports electric latch retraction. The 55 and 88 crossbar series are mechanical-only by design, with no electrified options at the device level. Every other active series in the Von Duprin lineup supports QEL. MEL is available on a narrower set of series.

• SeriesQELMELNotes
• 98/99 SeriesYes YesWidest electrified options catalog. QEL modular field conversion available. MEL factory-configured.
• 33A/35A SeriesYes YesNarrow-stile touchbar for aluminum storefronts. QEL modular field kit available. MEL factory-configured.
• 75 SeriesYes YesStandard commercial Grade 1. QEL modular field conversion available. MEL factory-configured.
• 22 SeriesYes NoMid-range commercial. QEL modular field conversion available. MEL not supported.
• 78 SeriesYes NoNarrow-stile push pad. QEL modular field conversion available. MEL not supported.
• 55 SeriesNo NoCrossbar, mechanical-only. No electrified options at device level.
• 88 SeriesNo NoCrossbar, mechanical-only. No electrified options at device level.

The QEL Modular Conversion Kit: Upgrading a Mechanical Von Duprin Panic Bar to Electric

Von Duprin 98/99 Series panic bar : supports QEL modular field conversion without device removal

The QEL modular conversion kit is the feature that makes electric latch retraction practical as a retrofit on existing Von Duprin panic bars. The kit replaces the dogging cover plate on the mechanism case and integrates a solenoid assembly that connects to the latch retraction mechanism inside the existing case. The device does not come off the door. The frame does not get cut. The installation typically takes under an hour per opening.

The conversion kit requires a power supply connection to the device and a signal connection from the access control panel's lock output. Once wired, the panic bar operates identically to a factory-configured QEL unit: the latch is mechanically extended and the door is locked under normal conditions, and the latch retracts when the access control panel sends a signal.

What the QEL Modular Kit Includes

The kit includes the solenoid assembly, the modified dogging cover, the solenoid mounting hardware, and the wiring connections that integrate the solenoid with the existing mechanism case. Series-specific kits are required because the mechanism case dimensions and dogging cover geometry differ between the 22, 33A/35A, 75, 78, and 98/99 Series. Always order the kit designated for the exact series installed on the door.

The QEL conversion kit does not include outside trim. Outside trim must be specified separately based on the function required at the opening: entry control only (pull or blank escutcheon outside), keyed outside entry (cylinder outside), or lever/knob for two-direction traffic with credential control provided only by the QEL signal.

When to Specify QEL and When to Specify MEL

Specify QEL When

• The opening is a standard commercial corridor, stairwell, or employee entrance where solenoid click is not an acoustic concern
• A retrofit upgrade is being done on an existing mechanical Von Duprin device and MEL is not an option for the installed series
• 12VDC power is available and a 24VDC supply would require additional wiring or power supply changes
• The project is specifying the 22 or 78 Series where MEL is not supported
• Budget is a primary constraint and QEL is specified at a lower cost than MEL at the factory configuration level

Von Duprin 22 Series panic bar : supports QEL only, not MEL

 

Specify MEL When

• The opening is in an acoustically sensitive environment where solenoid click is audible and disruptive: intensive care units, operating suites, neonatal units, executive offices, recording studios, or libraries
• The project specification calls for silent hardware operation at all electrified openings
• The access control system cycles the lock output frequently (high-credential-volume openings) and solenoid noise accumulation across many daily activations is a concern
• The opening is on the 98/99, 33A/35A, or 75 Series where MEL is a supported factory option
• The project is new construction or a full hardware replacement where factory configuration is available

Von Duprin 33/35A Series touchbar panic bar : supports both QEL and MEL for aluminum storefront access control applications

QEL and MEL on Fire-Rated Von Duprin Panic Bars

Both QEL and MEL are fully compatible with fire-rated Von Duprin panic bar configurations. The fire rating is determined by the device model suffix ("-F") and the UL listing of the complete assembly, not by whether the device includes an electric option. A 98-F QEL or 98-F MEL device carries the same UL fire rating as a mechanical 98-F device.

The critical point on fire-rated openings: QEL and MEL operate fail secure. The latch is extended and the door is latched whenever power is absent. A power failure does not release the fire door. This is the correct and required configuration for fire-rated assemblies per NFPA 80. Fail safe operation, where power failure would cause the door to release, is not available on Von Duprin exit devices and is specifically prohibited by NFPA 80 on fire-rated doors.

Companion Electrified Options: Chexit and ALK

Chexit Delayed Egress

Chexit is a Von Duprin electrified option that holds the door latched for 15 seconds after the push bar is pressed, while sounding a local alarm during the delay. At the end of 15 seconds, the latch retracts and the door opens. Chexit is not an access control function and does not work from a credential at the outside. It is an egress deterrence function specified on secondary exits to reduce unauthorized egress without preventing emergency exit.

Chexit and QEL or MEL serve different functions and are not substitutes. A single opening may have both: QEL or MEL providing access-controlled entry from the outside, and Chexit providing egress deterrence from the inside on the same push bar. This configuration is common on pharmaceutical storage rooms, secured data areas, and behavioral health wings in healthcare facilities.

ALK Alarm Exit Kit

The Von Duprin ALK alarm exit kit converts the standard panic bar push bar to an alarmed exit device. When the push bar is pressed, an 85-decibel alarm sounds from a battery-powered alarm module. The alarm is controlled by a mortise cylinder: turning the cylinder to the locked position enables the alarm, turning it to the unlocked position silences it for authorized egress. The ALK kit does not require a power supply connection and does not integrate with the access control system.

ALK is a standalone deterrence tool, not an access control integration. It is specified on secondary exits where budget does not support a full QEL or MEL installation but where some deterrence against unauthorized door use is required. For openings requiring both alarm deterrence and access control integration, the RX signal switch on a QEL or MEL device provides the event logging function while a separate alarm system handles the audio deterrence.

Power Requirements and Wiring for QEL and MEL

Power Supply Requirements

Both QEL and MEL require DC power. QEL devices are available in 12VDC and 24VDC configurations. MEL devices operate on 24VDC only. A dedicated regulated DC power supply, separate from the access control panel's internal supply, is required. The QEL solenoid draws approximately 300 to 500 milliamperes during latch retraction with a higher inrush current at the moment of activation. The MEL motor draws lower sustained current than the QEL solenoid and does not have the same inrush spike.

RX Request to Exit Switch

The RX (Request to Exit) switch is a micro switch inside the push bar that signals the access control panel when someone presses the push bar from the inside for egress. On QEL and MEL configured devices, the RX switch prevents the access control panel from generating a door-forced alarm every time an authorized user exits through the push bar. Without the RX signal, the panel sees the door opening without receiving a credential input and flags it as an unauthorized event.

The RX function is available on the 98/99, 33A/35A, 22, and 75 Series. It is wired on a separate low-voltage signal circuit from the QEL or MEL power circuit. Always specify the RX option on any QEL or MEL configured opening where the access control system monitors door events.

Von Duprin 75 Series panic bar : supports QEL and MEL, commonly specified for healthcare and standard commercial applications

 

QEL vs MEL vs Electric Strike: Choosing Between Device-Side and Frame-Side Solutions

For openings where outside access control is the requirement, facility teams sometimes choose between a QEL or MEL configured Von Duprin panic bar and a Von Duprin electric strike in the frame. Both achieve the same function: the door latches mechanically and unlocks on an access control signal. The choice depends on the door and frame conditions at the specific opening.

A frame-side electric strike is the simpler installation on existing openings where the frame can accept the strike cutout and the frame is not fire-rated in a way that prohibits the cutout. An electric strike does not require wiring to the door itself, which eliminates the need for a power transfer hinge or electrified door loop when the power must cross from the frame to the door-mounted device.

A device-side QEL or MEL configuration is preferred when the frame cutout for a strike would void the frame's fire rating, when the existing door and frame do not have the correct dimensions for an electric strike, or when the specification requires that all hardware maintain the full security engagement of the mechanical Von Duprin latch at the door edge rather than the frame-side keeper engagement of an electric strike.

For a detailed comparison of Schlage motorized latch retraction versus electric strike configurations, see the Schlage L9580 vs electric strike comparison guide at SecurityParts.com, which covers the same device-side vs frame-side decision for mortise lock applications.

Use this electric strike schematic diagram guide to wire any commercial electric strike installation correctly the first time. SecurityParts.com stocks Von Duprin electric strike parts and replacement components for the complete range of commercial electric strike configurations. Browse Von Duprin electric strike parts and diagrams by series, read the electric strike components and failure guide, or compare configurations in the Schlage L9580 vs electric strike comparison. Call 845-935-0301 or visit the SecurityParts.com contact page for pre-order wiring and specification support.

The Electric Strike Schematic Diagram: The Three-Element Circuit

Every electric strike schematic diagram, regardless of brand, voltage, or fail-mode configuration, is built on the same three-element series circuit. Understanding these three elements before looking at any specific diagram prevents the most common wiring mistakes.

The three elements are the power supply, the access control panel output relay (which acts as the switch in the circuit), and the electric strike solenoid. Current flows from the power supply, through the relay, to the strike solenoid, and back to the power supply. Nothing unlocks unless all three elements are correctly wired, powered, and functioning at the same time.

The Fail Secure Schematic Diagram (Normally Open Circuit)

In a fail secure configuration, the circuit between the power supply and the strike solenoid is normally open. No current flows to the solenoid under normal locked conditions. When an authorized credential is presented at the reader, the access panel closes its output relay for a programmed duration, typically 3 to 10 seconds, completing the circuit and energizing the solenoid to release the keeper. When the relay opens again, power stops, the solenoid de-energizes, and the keeper spring-returns to the locked position.

The Fail Safe Schematic Diagram (Normally Closed Circuit)

In a fail safe configuration, the circuit is normally closed. Current flows to the solenoid continuously during normal operation, keeping the keeper engaged in the locked position. When an access grant occurs, the access panel opens its relay, breaking the circuit, de-energizing the solenoid, and allowing the keeper to release. The door can then be pushed open without retracting the latchbolt. When the door closes again and the relay closes, current resumes and the strike re-locks.

Wire Gauge, Run Length, and Voltage Drop

Minimum Wire Gauge Requirements

Wiring methods for electric strikes must comply with ANSI/NFPA 70, the National Electrical Code. The minimum permissible wire size is 26 AWG based on published manufacturer installation guidelines, but this minimum is suitable only for very short runs in protected indoor locations. Commercial installations should use heavier gauge wire in nearly every case.

How Voltage Drop Affects Strike Performance

Voltage drop occurs because resistance in the wire reduces the voltage delivered to the solenoid at the end of the run. The longer the wire run and the thinner the gauge, the more voltage is lost before it reaches the strike. A solenoid that receives more than 10 percent below its rated voltage will actuate sluggishly or fail to release the keeper entirely.

A practical example: a 12VDC solenoid rated at 10 percent tolerance requires a minimum of 10.8 volts at the terminals. On a 22 AWG wire with a 100-foot round-trip run (50 feet each way), voltage drop is approximately 1.5 volts, leaving 10.5 volts at the strike. This is within tolerance. On a 150-foot round-trip run with the same wire gauge, voltage drop reaches approximately 2.2 volts, leaving 9.8 volts, which is below the 10.8-volt minimum. Use 18 AWG for that run instead.

Back EMF Protection: The Diode That Protects Your Access Panel

What Back EMF Is and Why It Matters

When a solenoid coil is de-energized, either because the relay opens (fail secure) or because a power failure occurs, the magnetic field inside the coil collapses instantly. This collapse induces a reverse voltage spike in the wiring, sometimes called back EMF (electromotive force). This spike can exceed several times the normal operating voltage for a fraction of a second and travels back through the wiring toward the access control panel's output relay.

Modern access control panels have solid-state output transistors that are sensitive to reverse voltage spikes. A single large spike or repeated smaller spikes can degrade or destroy the transistor, causing the panel's lock output to stop functioning while everything else on the panel continues to work normally. The failure looks like a wiring problem or a failed relay when the actual cause is cumulative back EMF damage from months of normal solenoid cycling.

How to Wire the Suppression Diode

A standard 1N4001 diode (or equivalent rated for at least 50V and 1A) wired in parallel across the solenoid terminals provides back EMF suppression. The diode is installed with its cathode (the banded end) toward the positive terminal of the strike and its anode toward the negative terminal. Under normal operation the diode is reverse-biased and carries no current. When the solenoid de-energizes and the reverse voltage spike occurs, the diode becomes forward-biased, creating a low-resistance path that absorbs and dissipates the spike before it reaches the access panel.

REX Switch and Door Position Switch Wiring

REX (Request to Exit) Switch Placement

A REX (Request to Exit) switch allows a person exiting the building through an access-controlled door to release the electric strike without credential verification. Pressing the REX button momentarily unlocks the strike from the inside, allowing egress without requiring a card, PIN, or key fob. This is required on most commercial access-controlled doors to prevent occupants from being trapped if the access control system fails.

In the schematic diagram, the REX switch connects in parallel with the access control panel's output relay. This wiring allows either the panel relay or the REX switch to independently complete the circuit and energize the solenoid. On fail secure systems the REX is a normally-open momentary contact switch. Pressing it closes the circuit, sends power to the solenoid, and releases the keeper for as long as the button is held or for a timed duration depending on the panel configuration.

Door Position Switch (DPS) Wiring

A door position switch monitors whether the door is physically open or closed and reports this status to the access control panel separately from the strike status. The DPS is a magnetic contact switch mounted in the door frame with a magnet on the door leaf. When the door is closed, the magnet keeps the switch in its resting state. When the door opens, the magnet moves away and the switch changes state, sending a signal back to the panel.

The DPS wiring runs on a completely separate circuit from the strike power wiring. It typically connects to a dedicated input terminal on the access control panel labeled "DI" (door input) or "DS" (door sensor). Mixing the DPS monitoring wiring with the strike power wiring is one of the most common installation errors and produces phantom door-open alarms that take significant time to diagnose.

Dual Switch (DS) Monitoring on Von Duprin Strikes

Von Duprin 6200 Series strikes with the DS (dual switch) option include two internal SPDT monitoring switches inside the strike body rather than requiring a separate external door position switch for basic strike status monitoring. One switch monitors the latchbolt tripper position (whether a latch bolt is seated in the strike pocket). The other switch monitors the keeper position (whether the keeper is fully returned to the locked position after a release cycle).

In the electric strike schematic diagram for a DS-equipped unit, the monitoring switch wires run back to the access panel's monitoring input terminals on a separate low-voltage circuit. The DS option produces two independent status signals that most modern access panels can display separately, allowing the panel to distinguish between a door that is closed-and-latched versus a door that is closed-but-not-fully-latched, a critical distinction on high-security openings. Browse Von Duprin electric strike parts including DS monitoring components at SecurityParts.com.

AC Power and the SO12/SO24 Rectifier Kit

Why Electric Strikes Require DC Power

Electric strike solenoids are designed for DC (direct current) power. The solenoid coil generates a sustained magnetic field that holds the plunger in position, and this requires the consistent unidirectional current flow that DC provides. AC (alternating current) reverses polarity 60 times per second in a standard US electrical circuit. This reversal causes the solenoid plunger to try to move in both directions 60 times per second, producing a buzzing vibration, generating significant heat, and causing accelerated solenoid wear or immediate failure.

The Von Duprin SO12 and SO24 Rectifier Kits

Von Duprin SO12 and SO24 rectifier kits are inline AC-to-DC conversion modules designed specifically for Von Duprin 6200 Series electric strike applications where only AC power is available from the building's low-voltage transformer. The SO12 converts AC input to 12VDC output. The SO24 converts AC input to 24VDC output. Both install inline between the AC power source and the strike terminals without any modification to the strike body or the frame.

In the schematic diagram, the rectifier kit appears between the AC power supply and the access control panel relay. The AC feeds into the rectifier, the rectifier outputs DC, and the DC then flows through the relay to the strike solenoid. The rectifier kit does not eliminate the need for a suppression diode if the access panel requires back EMF protection.

Terminal Block Connections: Step-by-Step Wiring Sequence

Identifying the Terminal Block

The electric strike terminal block is the connection point between the building wiring and the strike solenoid. On most Von Duprin commercial strikes, the terminal block is a small plastic block with two to six screw terminals inside the strike housing, accessible through a cover plate or directly from the frame side of the installation. Terminal labels vary by series. Most units mark terminals as COM (common), NO (normally open), or NC (normally closed) for relay output configurations, and as plus (+) and minus (-) for direct solenoid power connections.

On Von Duprin 6200 Series strikes with the DS monitoring option, the terminal block also includes two pairs of monitoring switch terminals in addition to the solenoid power terminals. These are physically separate from the power terminals and must be wired to separate input terminals on the access panel. Connecting the monitoring switch terminals to the power terminals will damage both the switch and the panel input.

Step-by-Step Terminal Connection Sequence

1. Verify power supply output voltage and type before any connections Use a multimeter to confirm the power supply outputs DC at the rated voltage (12VDC or 24VDC). Verify the no-load voltage does not exceed the solenoid rating by more than 10 percent. Many unregulated power supplies output significantly higher voltage under no-load conditions. A 12VDC rated supply may measure 14 to 15 volts without a connected load. Install a regulated power supply on any installation where voltage accuracy matters.
2. Cut power before making any terminal connections All connections to the terminal block must be made with the power supply disconnected. Making live connections risks a short circuit across the solenoid terminals, an immediate solenoid burn, or panel output relay damage. Confirm power is off with the multimeter before inserting any wires into the terminal block.
3. Connect the positive wire from the power supply to the positive (+) terminal The positive lead from the power supply runs through the access panel output relay before reaching the strike. Confirm the relay output terminal on the access panel and connect the wire from the normally-open (NO) terminal of the relay to the positive terminal of the strike. The incoming positive lead from the power supply connects to the COM terminal of the relay.
4. Connect the negative wire directly from power supply to strike negative terminal The negative (return) wire runs directly from the power supply negative terminal to the strike's negative terminal, bypassing the relay. The relay switches only the positive side of the circuit in standard commercial wiring.
5. Wire the REX switch in parallel with the access panel relay output Connect one terminal of the REX switch to the same wire junction as the relay's NO terminal and positive supply line. Connect the other REX terminal to the positive terminal of the strike. Pressing the REX switch now completes the circuit to the strike independently of the panel relay.
6. Install the back EMF diode across the strike terminals With power still off, connect a 1N4001 diode across the positive and negative terminals of the strike. Cathode (banded end) connects to the positive terminal. Anode connects to the negative terminal. The diode goes in parallel with the solenoid, not in series.
7. Connect door position switch or DS monitoring wires to separate panel input terminals If the strike includes DS monitoring or a separate door position switch is installed, run the monitoring wires to the dedicated input terminals on the access control panel. Do not combine these low-current monitoring wires in the same terminal as the solenoid power wires.
8. Restore power and test each function independently Apply power and use the access panel's test function to send an access grant signal. Confirm the keeper releases and returns. Test the REX switch independently. Confirm the DS monitoring reads correctly on the panel status display. Test the door position switch by opening and closing the door while watching the panel status indicator.

Von Duprin Series Wiring Differences

Von Duprin electric strikes across the 5100, 6100, 6200, and 6300 product lines share the same basic schematic diagram but have series-specific differences in terminal configuration, voltage options, and monitoring capabilities that affect the wiring before the installation begins.

Von Duprin 5100 Series

Von Duprin 6100 Series

Von Duprin 6200 Series

Von Duprin 6300 Series

Browse Von Duprin electric strike series parts and diagrams at SecurityParts.com. For parts specific to each series, the interactive parts diagram on each model page shows every terminal, component, and part number specific to that product.

Common Wiring Mistakes and How to Avoid Them

Sharing the Access Panel Power Supply with the Electric Strike

Most access control panels include a low-current internal power supply designed for the panel board and credential verification components. This internal supply is not designed to also power the solenoid. An electric strike solenoid draws 300mA to 500mA on activation, which can cause the panel's internal supply to sag, resetting the panel firmware or causing erratic relay behavior. Always power the electric strike from a dedicated, appropriately rated power supply that is separate from the panel's internal supply.

Running AC Power to a DC-Rated Solenoid Without a Rectifier

This is the single most common installation error in commercial electric strike work. The buzzing sound it produces is unmistakable and the solenoid damage it causes is rapid. If AC is the only power source available, install an SO12 or SO24 rectifier kit in-line before the strike terminals. If a Von Duprin rectifier kit is not the right fit for the installation, a standard full-wave bridge rectifier module with appropriate voltage and current ratings performs the same function.

Reversing the Back EMF Diode Polarity

A diode installed with reversed polarity (anode at positive terminal, cathode at negative) becomes a short circuit when the solenoid energizes. This blows the access panel's output fuse or destroys the output transistor within the first access grant. Always orient the diode with the cathode banded end toward the positive terminal. If uncertain, test the installation with a multimeter set to diode mode before powering the circuit.

Connecting Monitoring Switch Wires to Power Terminals

DS monitoring switches inside the strike operate at the low-current levels used by the access panel's input circuit, typically milliampere-level signals. The solenoid power terminals carry hundreds of milliamperes. Connecting the monitoring wires to the power terminals sends full solenoid current through the monitoring switch, burning the switch immediately and potentially damaging the access panel's input circuit. Always identify monitoring terminals separately from power terminals before making any connections.

Using Undersized Wire on Long Runs

An installation that tests correctly at 50 feet of wire and then fails intermittently at 150 feet is almost always a voltage drop problem caused by undersized wire gauge. The solenoid actuates on the bench, actuates correctly during initial commissioning, and then begins to fail intermittently as the solenoid winding heats up and its resistance increases slightly. Calculate voltage drop before selecting wire gauge. Use 18 AWG for runs over 75 feet on 12VDC systems.

SecurityParts.com stocks OEM Schlage deadbolt parts for the complete B Series range. Browse Schlage deadbolt replacement parts by model, the Schlage B Series deadbolt parts guide, and the Schlage strike plates and latch bolt parts guide. Call 845-935-0301 or visit the SecurityParts.com contact page for same-day parts identification support.

How to Read a Schlage Deadbolt Diagram

A Schlage deadbolt parts diagram shows the lock in an exploded view, with each component pulled apart from the others and numbered or labeled. The exploded view reveals how components nest together when assembled. The two sides of the diagram represent the outside of the door (the key cylinder side) and the inside of the door (the thumb turn side), connected through the door by the housing and the bolt assembly.

The strike assembly shown in the diagram is separate from the lock body and mounts into the door frame rather than the door itself. When ordering replacement parts, components from the door-side diagram are different products from the strike-side components, so identifying which side the failed part belongs to is always the first step.

The Outside Components: Key Cylinder Side

1. The Key Cylinder (Cylinder Plug and Shell)

The cylinder is the outermost component in the Schlage deadbolt diagram on the exterior side of the door. It consists of two main parts shown in the diagram: the cylinder plug (the rotating inner section that the key engages) and the cylinder shell (the outer housing that does not rotate). Inside the plug, the diagram shows a series of pin chambers running perpendicular to the plug face. Each chamber holds a key pin at the bottom and a driver pin above it, separated by the shear line when the correct key is inserted.

In a Schlage B Series single-cylinder deadbolt (B60N, B500, B600), there is one cylinder on the exterior side only. In a double-cylinder deadbolt (B62N, B502, B602), the diagram shows a cylinder on both the exterior and interior sides, replacing the thumb turn shown on single-cylinder models.

2. The Tailpiece (Cylinder Tailpiece)

The tailpiece is the rectangular or tab-shaped metal extension projecting from the back of the cylinder plug. It is the mechanical link between the rotating cylinder and the bolt mechanism inside the housing. When the key turns the cylinder plug, the plug rotates the tailpiece, and the tailpiece pushes against the cam inside the housing to extend or retract the bolt. This component is visible in the Schlage deadbolt diagram as the piece connecting the cylinder body to the housing assembly behind it.

Tailpiece failures produce a specific symptom: the key turns freely but the bolt does not move. This indicates the tailpiece has broken, deformed, or disengaged from the cam it drives. Browse Schlage deadbolt tailpiece replacement parts at SecurityParts.com.

3. The Outside Rose or Escutcheon

The rose (on standard B Series models) or escutcheon (on trim-specific variants) is the mounting plate visible on the outside face of the door surrounding the cylinder. On the Schlage B60N and B600 Series, this is a circular rose plate that covers the face bore and provides a finished appearance. The rose is held by mounting screws that pass through the door from the inside trim plate, so the rose itself has no external screws that can be removed from outside the door. This design prevents a simple external attack from defeating the trim mounting.

4. The Outside Mounting Plate and Through-Bolts

Behind the outside rose in the diagram are the mounting bolts that pass through the door from the inside trim to hold the entire outer trim assembly. On the B600 Series Grade 1 models, these are hardened machine screws. The diagram shows their path through the door edge and into the interior trim mounting holes. Loose or missing through-bolts produce a wobbling or spinning outer rose and are the most common reason the exterior trim feels loose even when the bolt mechanism is intact.

The Central Assembly: Bolt, Housing, and Faceplate

5. The Deadbolt (Bolt Throw)

The deadbolt itself is the horizontally moving steel bar shown in the center of the diagram, extending from the door edge into the strike box when the lock is in the locked position. On Grade 1 Schlage B Series models (B250, B500, B600 Series), the bolt has a 1-inch throw, meaning it extends one inch beyond the door edge when fully locked. On Grade 2 models (B350, B352), the throw is 5/8 inch.

The bolt face is square-cornered in the Schlage B Series, not beveled. A beveled latch is a spring latch that closes automatically; a square-cornered deadbolt requires deliberate key or thumb turn operation to extend or retract. This distinction is important when reading the diagram: the square face bolt shown is the deadbolt, not the spring latch used in cylindrical locks.

6. The Anti-Saw Pin (Hardened Steel Insert)

The Schlage deadbolt diagram for B600 Series Grade 1 models shows a small pin or cylinder of hardened steel embedded within the bolt body. This is the anti-saw pin. Its function is to defeat a forced entry technique where the attacker saws through the bolt by pressing a hacksaw blade between the door edge and the strike while the bolt is engaged. When the saw blade contacts the anti-saw pin, the pin spins freely inside the bolt body, preventing the blade from making sustained contact and cutting through. Grade 2 models (B350 Series) do not include the anti-saw pin, which is one of the key differences visible between Grade 1 and Grade 2 bolt assemblies in the diagram.

7. The Bolt Housing and Retainer

The bolt housing is the metal case inside the door body that encases the bolt mechanism, the cam assembly, and the tailpiece connection. In the exploded diagram, the housing appears as the central body of the lock into which the cylinder tailpiece enters from one side and the thumb turn cam enters from the other. The housing is secured to the door face by the faceplate screws.

A retainer clip or retaining ring shown in the diagram holds the bolt within the housing so it moves in a straight linear path without rotating. A failed retainer clip causes the bolt to rotate instead of traveling straight, which prevents it from seating correctly in the strike box.

8. The Faceplate and Mortise Pocket

The faceplate is the flat metal plate visible on the door edge when looking at the door from the side. It covers the opening of the mortise pocket cut into the door edge and has two countersunk screw holes that secure the housing to the door. On the B500 and B600 Series, the faceplate is square-corner 1-1/8 inch by 2-1/4 inch. The backset (the horizontal distance from the door edge to the center of the face bore) is adjustable on all Schlage B Series deadbolts between 2-3/8 inches and 2-3/4 inches.

The Inside Components: Thumb Turn Side

9. The Thumb Turn

The thumb turn is the knob or lever on the interior face of the door that operates the deadbolt from inside without a key. It connects to a cam inside the housing through a spindle or through-bolt arrangement. Turning the thumb turn 90 degrees rotates the cam, which drives the bolt to the extended or retracted position. In the Schlage B Series diagram, the thumb turn is shown with its cam engagement visible in the exploded view, separate from the thumb turn knob itself.

Thumb turn failures are usually one of two types: the thumb turn spins freely without moving the bolt (broken cam engagement or stripped spindle connection) or the thumb turn is difficult to operate (bent bolt from door-slam damage or misalignment between the bolt and the strike). Identifying which failure type is occurring points directly to which component in the diagram needs replacement.

10. The Inside Rose or Escutcheon

The inside rose mirrors the outside rose in appearance but mounts the interior thumb turn and holds the through-bolts that secure the entire assembly to the door. On B600 Series models, the inside trim includes a more substantial mounting plate behind the rose that anchors the lock body against forced entry attempts from the outside. Removing the inside rose gives access to the through-bolt heads, which allows the entire lock assembly to be removed from the door for service or replacement.

The Strike Assembly: Frame-Side Components

11. The Strike Plate and Strike Box

The strike plate and strike box are shown in the Schlage deadbolt diagram as a separate assembly that mounts into the door frame rather than the door itself. The strike plate is the visible metal plate on the door frame face with a rectangular opening through which the bolt passes. The strike box is the recessed metal box behind the strike plate that receives the full 1-inch bolt throw when the door is locked.

The strike box is a critical security component that most residential installations omit. Without a strike box, the bolt passes through the strike plate opening into wood only. A kick-in attack splits the wood and the bolt pulls through. With a strike box, the bolt enters a metal pocket that distributes the force of a kick-in attack across the full depth of the box, which is substantially more resistant to forced entry. Grade 1 B600 Series installations should always use the provided strike box, not the strike plate alone.

12. Strike Box Reinforcement Screws

The diagram for the B500 and B600 Series strike plate shows two types of screws: standard installation screws (which only penetrate the door jamb) and optional 2-inch reinforcement screws (Schlage part J250-028) that penetrate past the jamb and into the structural framing behind it. The standard screws provide adequate performance for normal use. The 2-inch reinforcement screws dramatically increase the resistance of the strike assembly to kick-in forced entry by anchoring the strike into structural wood rather than just the jamb material. Browse Schlage strike plate and reinforcement parts at SecurityParts.com.

Grade 1 vs Grade 2: What the Diagram Shows Is Different

Using the Diagram to Identify the Failed Part

When something goes wrong with a Schlage deadbolt, the symptom usually points directly to a specific numbered component in the diagram. Use this symptom-to-component mapping to identify the right part before ordering.

• Key turns, bolt does not moveTailpiece broken or disengaged from cam. Check tailpiece first before replacing cylinder.
• Key stiff or hard to turnCylinder plug pins worn or corroded. Lubricate with dry graphite first; replace cylinder if stiffness persists.
• Thumb turn spins freelyCam inside housing stripped or thumb turn spindle broken. Requires housing or cam replacement.
• Bolt extends but will not retractBolt is bent from door-slam impact or misaligned with strike. Check alignment before replacing bolt assembly.
• Bolt will not fully extendStrike box misaligned or door has shifted. Confirm the strike box centerline aligns with the bolt centerline before ordering any parts.
• Outside rose spins or wobblesThrough-bolts loose or missing. Tighten through-bolts from inside trim before diagnosing further.
• Door can be kicked in despite locked boltStrike box missing or strike screws too short. Install strike box and 2-inch reinforcement screws.

Single Cylinder vs Double Cylinder: Diagram Differences

The most common version of the Schlage B Series deadbolt diagram is the single-cylinder configuration (B60N, B500, B600) where the inside shows a thumb turn and the outside shows a key cylinder. The double-cylinder version (B62N, B502, B602) replaces the thumb turn with a second key cylinder on the interior side.

The diagram difference is significant for parts ordering. A single-cylinder deadbolt uses a thumb turn assembly, a cam, and one cylinder. A double-cylinder deadbolt uses two cylinders, two tailpieces, and no thumb turn or cam assembly. When ordering a replacement cylinder for a double-cylinder installation, both cylinders must be specified to maintain a keyed-alike configuration if both sides share the same key.

The Adjustable Backset: What It Means for Replacement Parts

Every Schlage B Series deadbolt diagram shows a two-position backset adjustment. The standard backset positions are 2-3/8 inches and 2-3/4 inches, measured from the door edge to the center of the face bore hole. Most commercial door hardware installations use the 2-3/4 inch backset because it is compatible with the wider door stile dimensions common in commercial hollow metal frames. Residential entry doors often use the 2-3/8 inch position.

The backset setting does not change which bolt, housing, or cylinder you need. It changes where the strike plate is positioned on the door frame. A Schlage deadbolt moved from a 2-3/8 inch backset door to a 2-3/4 inch backset door needs the strike plate repositioned but uses the same lock body. Confirming the backset before ordering the strike plate prevents ordering a strike that puts the bolt pocket in the wrong position.

Model Number Reference: B Series Diagram Variants

The Schlage B Series includes several model lines, and the diagram varies slightly between them. Knowing which series is installed before consulting the diagram prevents confusion between models that look similar but use different parts.

The B60N is the most common single-cylinder deadbolt in the residential and light commercial B600 Series. The diagram shows Everest 29 S or T keyway cylinder, 1-inch bolt with anti-saw pin, and square-corner faceplate. The B62N is the double-cylinder version of the same series. The B500 Series and B600 Series are the commercial Grade 1 versions with SFIC and FSIC cylinder options visible in the diagram alongside the standard cylinder. The B250 Series (Grade 1) and B350 Series (Grade 2) are the commercial lines where the Grade difference is reflected in the bolt assembly shown in the diagram.

Browse all Schlage hardware and deadbolt parts at SecurityParts.com, or see the commercial deadbolt parts guide for model-specific identification. For cylindrical lock parts that use a spring latch rather than a deadbolt, see the Schlage cylindrical lock parts catalog. For mortise lock deadbolt assemblies used in L Series locks, see the Schlage mortise lock parts catalog.