Quick Answer

Security Parts stocks 29 replacement components for the LCN 4210 and 4210T Smoothee high security door closer series. The most frequently replaced parts are the three arm assemblies for the 4210 (EDA Arm, Cush Arm, Hold Open Cush Arm) and the track components for the 4210T. The cylinder assembly and metal security cover are handed and must be specified at order. Before ordering any part, confirm the model variant (4210 or 4210T), the hand, the cylinder size, and the finish. Closer adjustments are not accessible with the security cover installed -- the cover must be removed first. Call 845-935-0301 to confirm specifications before placing an order.

What Is the LCN 4210 Smoothee Series?

The LCN 4210 Smoothee Series is a heavy duty, high security surface-mounted parallel arm door closer built for correctional, institutional, vandal-prone, and high-traffic applications. It has passed 10 million cycles in independent testing and is tested and certified under ANSI Standard A156.4, Grade 1. The 4210 carries a ten-year warranty. The series includes a high-strength cast iron cylinder, a one-piece forged steel piston, a double-heat-treated pinion, all-weather hydraulic fluid, tamper-resistant regulating screws, and a high-efficiency full-complement low-friction bearing.

The LCN 4210 is a parallel arm push-side mount closer. The related 4510 is the hinge pull-side version. The 4210T is the track arm variant of the 4210, with a high security threaded track roller that cannot be removed without disconnecting the arm from the closer. All three share the same fundamental cylinder body but use different arm assemblies, covers, and accessories that are not interchangeable.

For a broader overview of LCN closer families stocked at Security Parts, see the door closers parts guide and the LCN 4000 series parts guide.

What Is the Difference Between the LCN 4210 and 4210T?

The 4210 and 4210T share the same cast iron cylinder body but use entirely different arm systems. Knowing which variant is installed determines which arm, cover, drop plate, and arm screw to order.

The model number is stamped on the closer body near the packing nut at the base of the pinion. Numbers such as "71" or "320G" found elsewhere on the body are manufacturing reference numbers and cannot be used to order parts.

Can I Access the LCN 4210 Adjustment Valves With the Cover On?

No. This is one of the most important service facts about the 4210 series and the detail most frequently overlooked. The LCN 4210 metal security cover uses four-point mounting precisely to resist tampering, and as a result, closer adjustments are not accessible with the cover installed. The cover must be removed before any regulation valve adjustment, spring power adjustment, or closer service can be performed.

On standard LCN series closers, the snap-on cover allows quicker access. The 4210 metal security cover is a different design and must be fully removed. Confirm the cover screw is the correct replacement (4210-31 for the 4210, 4210T-31 for the 4210T) when reinstalling after service.

What Torx Bit Size Does the LCN 4210 Use?

The LCN 4210 uses Torx fasteners as standard, which is one of its tamper-resistant features. The bit sizes required depend on the screw being driven.

LCN does not supply Torx wrenches with the closer. These are standard sizes that any professional installer will have available. If the installation uses the thru-bolt screw pack (4210-TBTRX), confirm the correct bit size for the specific fasteners in that pack before starting.

What LCN 4210 Parts Are Available?

All 29 LCN 4210 and 4210T Smoothee series replacement parts stocked at Security Parts are listed below. Parts for the 4210 and 4210T are noted separately. Several parts are shared between both variants.

Arm Selection: Which LCN 4210 Arm Do I Need?

Arm selection is the most common decision when ordering LCN 4210 parts. The 4210 offers three arm types for the standard parallel arm configuration. The 4210T uses a single track arm. The correct arm depends on whether a built-in stop, hold-open, or track configuration is required for the application.

What Is the LCN 4210 Extra Duty Arm (EDA)?

The 4210-3077EDA Extra Duty Arm is the default arm shipped with the 4210 closer. It is non-handed, solid forged steel, with a double slab arm-to-pinion attachment for maximum strength. The EDA arm does not include a built-in stop and is designed for potentially abusive installations. Because it is non-handed, the same part fits both left-hand and right-hand doors. It is UL listed for self-closing door applications.

If a door stop is needed on an EDA arm installation, it must be a separate overhead stop or wall stop device, not a CUSH arm accessory. Using a separate stop device alongside a CUSH arm installation is redundant and not recommended.

What Is the LCN 4210 Cush Arm (CUSH-N-Stop)?

The 4210-3077CNS Cush Arm is an optional handed parallel arm with a built-in stop in the soffit shoe. CUSH stands for Cush-N-Stop. When the door reaches its templated maximum opening angle, the arm contacts the stop in the shoe and arrests the door without any separate stop device.

The Cush Arm is forged solid steel with a double slab arm-to-pinion attachment. It is handed and must be specified left-hand or right-hand at order. Templated maximum openings are available at 85 degrees (A = 8-5/16 in., B = 9-5/8 in.) and 90 degrees (A = 7-11/16 in., B = 9 in.).

The drop plate (4210-18) is required for all Cush Arm installations. The CUSH shoe support (4210-30) is required when the frame reveal is less than 3-1/16 inches. The fifth hole spacer (4210-201) works alongside the CUSH shoe support. Order all three at the same time to avoid installation delays.

What Is the LCN 4210 Hold Open Cush Arm?

The 4210-3049CNS Hold Open Cush Arm provides both a built-in stop and a hold-open function in a single arm. A handle on the arm controls when the hold-open is engaged. Two important restrictions apply: the Hold Open Cush Arm is not available with the 4216 cylinder, and the Delayed Action cylinder option is also not available with the 4216. Confirm the cylinder variant before ordering this arm.

What Is the LCN 4210T Standard Track Arm?

The 4210T-3077T Standard Track Arm is the arm used on the 4210T track variant. It is handed with a large cross-section forged steel arm. The high security feature is the threaded attachment between the arm and the track roller (4210T-3034). The roller threads into the arm for extra strength and cannot be removed without disconnecting the arm from the closer body. The roller is included when the 4210T-3077T arm is ordered separately.

Metal Security Cover: LCN 4210-72MC and 4210T-72MC

The metal security cover is a standard component of both the 4210 and 4210T and is one of the distinguishing features of the Smoothee series. It uses four-point mounting for extra tamper resistance compared to two-point mounting on standard LCN series covers. The cover is handed and must match the finish of the installed hardware.

The 4210 uses the 4210-72MC and the 4210T uses the 4210T-72MC. These covers are different and cannot be substituted between the 4210 and 4210T. The cover is secured by the cover screw (4210-31 for the 4210, 4210T-31 for the 4210T).

An important service reminder: closer adjustments are not accessible with the cover installed. The cover must be fully removed before any regulation valve or spring adjustment. After service, reinstall the cover and confirm all four mounting points are secured with the correct cover screw.

Drop Plate, CUSH Shoe Support, Blade Stop Spacer, and Flush Panel Adaptor

Four accessories are required or optional depending on the frame conditions of the specific installation. These are frequently missed at order time and are among the most common causes of delayed installations.

When Is the LCN 4210-18 Drop Plate Required?

The 4210-18 Drop Plate has two trigger conditions.

• The top rail is less than 5-1/8 inches measured from the stop on a push-side mount.
• Any Cush Arm or Hold Open Cush Arm installation, regardless of top rail depth.

One dimension that every competitor misses: the plate requires a minimum top rail of 2 inches measured from the stop. If the top rail is less than 2 inches, the drop plate cannot be used. The plate ships with TORX screws. The 4210-18 is physically the same plate as the 4110-18, but the 4210-18 ships with TORX screws for high security mounting, while the 4110-18 does not. Do not substitute a 4110-18 on a 4210 installation.

The 4210T uses the 4210T-18 Drop Plate, triggered when the top rail is less than 5-1/4 inches, with a 2-1/4-inch minimum top rail required.

When Is the LCN 4210-30 CUSH Shoe Support Required?

The 4210-30 CUSH Shoe Support is needed when a Cush or Hold Open Cush Arm is installed and the frame reveal is less than 3-1/16 inches. The five-screw connection at the CUSH shoe is critical because the built-in stop generates significant force during the door arresting action. The CUSH shoe support provides anchorage for the fifth screw when the jamb depth is too shallow for a standard installation. Without it on shallow frames, the shoe will pull away from the frame under repeated use.

When Is the LCN 4210-419 Flush Panel Adaptor Needed?

The 4210-419 Flush Panel Adaptor is needed when the CUSH shoe must mount to a single rabbeted or flush frame that does not provide a horizontal mounting surface for the shoe. The adaptor creates the required horizontal surface.

When Is the LCN 4210-61 Blade Stop Spacer Needed?

The 4210-61 Blade Stop Spacer is needed when a 1/2-inch blade stop is installed in the frame. The spacer lowers the parallel arm shoe to clear the blade stop. Without it, the shoe contacts the blade stop before the door reaches its full intended opening angle.

What Does AVB Mean on the LCN 4210 Cylinder?

AVB stands for Advanced Variable Backcheck. It is an optional cylinder feature ordered with the suffix CYLAVB. On a standard LCN closer, backcheck begins at approximately 75 degrees of door opening, providing resistance against the door being forced or blown open. With AVB, backcheck starts at approximately 45 degrees, providing earlier and more pronounced resistance.

AVB is available on the 4210 series cylinder. It is useful in high-wind locations, on heavy-traffic openings where doors are routinely pushed open aggressively, or in any application where resistance at a lower opening angle reduces the risk of the door striking an adjacent wall or object. Specify CYLAVB when ordering the cylinder if AVB is required.

Can the LCN 4210 Hydraulic Fluid Be Refilled in the Field?

No. The hydraulic fluid in an LCN closer must not be refilled in the field. If a 4210 is showing signs of hydraulic fluid leakage, the appropriate response is closer replacement, not a fluid top-off. Attempting to refill the fluid voids the warranty and is explicitly stated as not permitted in LCN service guidance.

The all-weather hydraulic fluid in the 4210 performs without variation between -30 degrees F and +120 degrees F. This eliminates the need for seasonal closing speed adjustments that affect standard hydraulic closers. If a 4210 installation requires frequent speed adjustments as seasons change, the more likely cause is a seal or valve issue, not the fluid composition.

What Is the LCN 4210 Regulation Valve Adjustment Limit?

All LCN door closers have three regulating valves: General Speed (main closing speed), Latch Speed, and Backcheck. The 4210 follows this same three-valve design. LCN recommends not opening or adjusting the regulation valves more than 3 full turns from the shutoff position. Opening the valves beyond this limit can damage the seals and cause hydraulic fluid leaks. The regulation valve assemblies are staked to provide a physical warning when the screws approach maximum adjustment, but they do not mechanically prevent over-adjustment.

If the door does not latch after adjusting the latch speed valve, the solution is to increase spring power, not to open the latch speed valve further. Increasing the latch speed valve opening changes the closing rate but does not increase the closing force available for latching. Increasing closing force requires spring power adjustment on the Green Dial.

For step-by-step guidance on adjusting LCN door closer speed and spring settings, see the guide to adjusting a commercial door closer.

Does the LCN 4210 Require Periodic Maintenance?

Closers mounted according to LCN installation instructions require no periodic maintenance or seasonal adjustments. The all-weather hydraulic fluid handles the full operating temperature range without change to closing time. Monthly, quarterly, and annual visual inspections are recommended for Fire and Life Safety rated installations only. For those applications, inspection intervals should align with the applicable fire code schedule.

The practical implication for facilities maintenance staff is that a correctly installed 4210 in a standard application should not need routine service. If a 4210 on a routine installation is requiring frequent readjustment, that indicates an installation issue (incorrect spring size for the door weight, incorrect valve settings, damaged seal) rather than a normal maintenance need.

How Do I Read the LCN 4210 Date Code?

The LCN date code is a four-digit code found on the closer body. The first two digits indicate the week of manufacture and the last two digits indicate the year. A date code reading "2519" means the closer was manufactured in week 25 of 2019. This is useful when assessing whether a closer is within warranty, identifying when parts were last installed, or planning replacement schedules on a building's door hardware inventory.

Do not confuse the date code with manufacturing reference numbers such as "71" or "320G" that may appear stamped elsewhere on the cylinder assembly. Those numbers are internal references and cannot be used to order replacement parts.

Can a 4510T Track Be Converted to a 4210T Track?

Yes. The 4210T-3038 standard track and the 4510T-3038 track are physically the same track, with one difference: the 4510T includes a spacer bar that the 4210T does not use. To convert a 4510T installation to a 4210T, remove the spacer bar from the 4510T track and replace the metal cover with the handed 4210T-72MC cover in the correct finish. The 4210T and 4510T use different handed metal covers, so the cover cannot be reused from the 4510T. The 4210T-3034 track roller and the threaded arm attachment remain the same across both models.

This conversion is useful when an existing 4510T installation needs to change its mounting orientation from hinge pull-side to push-side parallel arm. The core cylinder and track can be retained; only the cover needs to change. Confirm the handing matches the new door swing before ordering the replacement cover.

LCN 4210 Screw Packs: TORX vs Thru-Bolt

The 4210 uses Torx machine screws as standard, not the SRT (Self Reaming and Tapping) screws used on most standard LCN closer families. Two screw pack options are available.

How Do I Order the Correct LCN 4210 Replacement Part?

Confirm each of the following before placing an order to avoid receiving a part that does not fit the installation.

View the full parts listing and diagrams at the LCN 4210 and 4510 Smoothee series parts page. Call 845-935-0301 for pre-order identification support or to confirm specifications before ordering.

Troubleshooting Common LCN 4210 Field Issues

Where Is the LCN 4210 Typically Installed?

Understanding the typical application environments for the LCN 4210 helps clarify why specific parts and accessories matter on a service call. The 4210 and 4210T are not general-purpose commercial closers. They are specified for environments where standard commercial closer components would not hold up to the demands of the installation.

Correctional and Detention Facilities

The 4210 is designed specifically for correctional applications. The TORX fasteners prevent unauthorized removal of the arm and cover. The four-point metal cover mounting resists prying. The forged steel arm provides strength against deliberate abuse. In these environments, every part matters: a cover screw (4210-31) that is stripped or a CUSH shoe that has pulled away from the frame is a security gap, not just a maintenance issue.

Institutional and High-Traffic Openings

Schools, university buildings, hospitals, and government facilities specify the 4210 on openings with very high cycle counts and some vandalism risk. The 10-million-cycle test rating reflects this use case. In these environments, the track roller (4210T-3034) on 4210T installations is the component most likely to show wear first, followed by the arm screw (4210-159 or 4210T-159).

What Is the Maximum Door Weight for the LCN 4210?

The maximum recommended door weight for LCN manual closers is 225 pounds. For the 4210, cylinder sizes 1 through 6 cover interior doors up to 5 feet wide and exterior doors up to 4 feet wide (for sized cylinders). Non-sized cylinders adjust for interior doors up to 4.5 feet and exterior doors up to 3.5 feet. The size 1 (4211) cylinder meets ADA opening force requirements when set at 5 pounds. For the LCN door closer sizing guide, including which cylinder size to specify for a given door weight and width, see the LCN door closer sizing guide.

LCN 4210 vs LCN 4110: Key Differences

The 4210 and 4110 share a similar naming structure and several accessories use the same part body. But they serve different security levels and must not be treated as interchangeable.

• The 4210 uses TORX fasteners as standard. The 4110 uses standard screws.
• The 4210 metal cover uses four-point mounting. The 4110 uses two-point mounting.
• The 4210-18 drop plate ships with TORX screws. The 4110-18 plate ships without them.
• The 4210 cylinder is a heavier cast iron unit rated for correctional applications. The 4110 cylinder is a standard cast iron unit.
• Arms are not interchangeable between the 4210 and 4110 series.

If an installation is marked 4110 but shows TORX fasteners and a four-point cover, verify the model number stamped near the pinion. A 4210 may have been substituted at install. Use the stamped model designation near the pinion as the authoritative source for part identification, not the original specification sheet or the cover appearance. This is especially common on retrofitted correctional openings where the original specification called for a 4110 but the installing contractor upgraded to the 4210 for the security cover. In those cases, ordering 4110 arms or a 4110 cylinder on a subsequent service call will result in parts that do not fit. Always verify at the pinion. The model number stamped on the body is the only reliable identification method for LCN high security closers. For the complete parts listing with diagram references showing which part attaches where on the closer body, use the series parts page to cross-reference visual diagrams against the stamped model number before placing any order. Diagram 1 shows the arm and cover components. Diagram 2 shows the cylinder and accessory positions. Having both open when ordering reduces the chance of ordering the wrong handed component or missing a required accessory.

How to Read the LCN 4210 Model Number

The model number stamped near the pinion follows a consistent pattern. The series designation (4210 or 4210T) is followed by a size digit (1 through 6) indicating the cylinder size. Common model number designations found on installed 4210 closers include:

• 4211 or 4211T: Size 1 cylinder, adjustable from Size 1 to 5 (ADA opening force capable)
• 4212 or 4212T: Size 2 cylinder
• 4213 or 4213T: Size 3 cylinder
• 4214 or 4214T: Size 4 cylinder
• 4216 or 4216T: Size 6 cylinder (note: Hold Open Cush Arm and Delayed Action not available)

Cylinder suffixes such as DEL (Delayed Action), CYLAVB (Advanced Variable Backcheck), and handing codes (LH, RH) follow the size digit in the full model string. Always read the full model string from the closer body before ordering cylinder assemblies or confirming arm compatibility.

Security Parts has supplied genuine OEM commercial door hardware components to locksmiths, glaziers, facilities managers, contractors, and security integrators since 2001. All 29 LCN 4210 and 4210T Smoothee series replacement parts listed in this guide are stocked and available for individual order. Security Parts carries genuine OEM LCN components, ensuring that replacement parts match the original specifications for fit, finish, material, and security rating.

The LCN 4210 is a high security product where correct part identification matters considerably more than on standard commercial closer series. An incorrectly handed arm or cover on a correctional or institutional opening can compromise the security intent of the installation. A CUSH arm ordered without the required accessories (drop plate, CUSH shoe support, fifth hole spacer) will arrive on site incomplete, causing delays. Confirm the model number, hand, cylinder size, cylinder type, and finish from the installed hardware before placing any order. If the model label is unreadable, the handing is unclear, or the cylinder suffix is not visible, call 845-935-0301 for identification support before ordering any LCN 4210 part.

All LCN 4210 parts verified in this guide are linked directly to their live product pages at Security Parts. For the complete parts listing with diagram references, see the LCN 4210 and 4510 Smoothee series parts and diagrams page.

Related Resources at Security Parts

• LCN 4210 and 4510 Smoothee Series Parts and Diagrams
• Door Closers Parts Guide
• LCN 4040XP Parts Guide
• LCN 4050AT Parts Guide
• LCN 4000 Series Parts Guide
• How to Install a Commercial Door Closer
• How to Adjust a Commercial Door Closer
• LCN Door Closer Sizing Guide