Quick Answer

The LCN 4050AT is a heavy-duty door closer that uses an AutoTemplate overhead concealed parallel arm system. Before ordering any LCN 4050AT parts, confirm these four things:

• 4050AT vs 4050A: These are completely different products. The 4050A is a surface closer. The 4050AT uses a concealed overhead parallel arm track system. Their parts are not interchangeable.
• Track variant: Four track options exist: 3038 (standard), 3038H (hold-open), 3038B (standard with bumper), and 3038HB (hold-open with bumper). Match the track to the function the door requires.
• Roller match: The 3034 standard roller goes with standard tracks. The 3034H hold-open roller goes with hold-open tracks. A mismatched roller will prevent hold-open function from engaging.
• Double egress: If the door swings in both directions, you need the 3077DE track arm and 78DE main arm and tube. Standard arms only swing one way.
• 40 LCN 4050AT parts are stocked at Security Parts across all track, arm, roller, cylinder, cover, and hardware configurations.

Call 845-935-0301 for pre-order compatibility support before placing your order.

What the LCN 4050AT Is

The LCN 4050AT is the AutoTemplate configuration of the LCN 4050 Series heavy-duty door closer. Unlike the surface-mounted 4050A, the 4050AT uses an overhead concealed parallel arm track system. The closer body mounts inside the door header or above the door frame, and the arm travels along a track rail mounted to the door face to control the swing.

The 4050AT is commonly specified on heavy institutional doors in healthcare, education, and government facilities where a surface-mounted closer would create an obstruction or aesthetic conflict. The concealed track arm keeps the closer mechanism above the door line and out of the traffic path.

The 4050AT is a separate product from the 4050A. The two share some model naming but use completely different installation configurations and part catalogs. For guidance on the LCN 4050A surface closer and other LCN 4000 series models, see the LCN 4000 series parts guide. For related LCN overhead parallel arm closers, see the LCN 1250 parts guide and the LCN 1450 parts guide.

LCN 4050AT Track Arms

LCN 4050AT-3077T Standard Track Arm. View product page and order.

The track arm connects the closer spindle to the track roller and converts the rotational output of the closer into the linear sliding movement that controls door swing. Two track arm configurations are stocked.

4050AT-3077T: Standard Track Arm

The 4050AT-3077T is the standard track arm for single-direction swing doors. It attaches at the closer spindle on one end and connects to the track roller on the other. Replace when the arm is bent, cracked, or the spindle connection has stripped and the arm cannot be secured.

4050AT-3077DE: Double Egress Track Arm

The 4050AT-3077DE is the track arm for doors that swing in both directions. Double egress doors are common in healthcare corridor applications where staff push through from either side. The 3077DE arm must be used with the 4050AT-78DE main arm and tube; the standard arm components are not compatible with double egress configurations.

Also needed for arm attachment:

• 4050AT-159 arm screw: The primary screw that secures the track arm to the closer spindle.
• 4050AT-83H set screw: The set screw that locks the arm at the correct spindle engagement depth.
• 4050AT-82 rod: The connecting rod between the main arm and the track arm on double egress configurations.

LCN 4050AT Track Assemblies

LCN 4050AT-3038 Standard Track. View product page and order.

The track is the rail mounted to the door face that guides the track roller as the door swings. Four track variants are stocked for the 4050AT, each serving a different functional requirement.

Choosing the Right Track Variant

The bumper variants add a rubber cushion at the open-limit end of the track that absorbs impact and reduces slam noise at the fully open position. Specify a bumper track when the door contacts a wall, stop, or another surface with enough force to cause noise or damage.

Also stocked for track installations:

• 4050AT-169 track bumper assembly: A standalone replacement bumper for existing tracks that have lost or worn through their original bumper cushion.
• 4050AT-73 end cap: The cap at the end of the track that retains the roller assembly within the track travel range.
• 4050AT-425 roller lock screw: Secures the roller assembly in the track after installation. Replace when the roller is moving laterally in the track between service calls.

LCN 4050AT Track Rollers

LCN 4050AT-3034 Track Roller. View product page and order.

The track roller slides in the track rail and connects the arm assembly to the sliding movement that controls door swing. Two roller configurations are stocked, and they must be matched to the correct track type.

• 4050AT-3034: Standard track roller. Used with 4050AT-3038 and 4050AT-3038B tracks.
• 4050AT-3034H: Hold-open track roller. Used with 4050AT-3038H and 4050AT-3038HB tracks. The 3034H includes the engagement geometry needed for the hold-open function to arrest the door at the fully open position.

Installing a standard 3034 roller in a hold-open track defeats the hold-open function. The door will still close but will not hold at the open position. Replace the roller first when hold-open function has stopped working and the track itself appears undamaged.

Hold-Open Clip: 4050AT-3054

The 4050AT-3054 hold-open clip works with the hold-open roller and hold-open track to arrest the arm at the fully open position. The clip is a wear component on high-cycle doors. Replace when the door no longer holds at the open position despite having the correct 3034H roller and 3038H or 3038HB track installed.

LCN 4050AT Cylinder Assembly

LCN 4050AT-3071 Cylinder Assembly. View product page and order.

The 4050AT-3071 standard cylinder assembly is the main hydraulic mechanism of the 4050AT closer. It controls closing speed and latching speed through internal valves. Replace the cylinder assembly when:

• The door swings freely without resistance (complete hydraulic loss)
• Closing speed and latching speed cannot be adjusted through the valve screws
• Hydraulic fluid is visible on or around the closer body
• The closer makes no resistance on the closing stroke even after adjustment

If the door closes but slams or is too slow to latch, try adjusting the closing and latching speed valves before ordering the cylinder assembly. If adjustment has no effect, the seals inside the cylinder have likely failed. For guidance on adjustments, see the how to adjust a commercial door closer guide.

Drop Plates and Mounting Hardware

The 4050AT uses drop plates to position the closer body at the correct height relative to the door and frame geometry. Two drop plate configurations are stocked:

• 4050AT-18: Standard drop plate for top rail mounting. Used when the closer body requires standard drop height to align with the track.
• 4050AT-18G: Alternate drop plate for modified top rail geometry. Confirm the existing plate part number from the installed unit before ordering.

Shaft Extender: 4050AT-480

The 4050AT-480 shaft extender bridges the gap between the closer spindle and the track arm on installations where the standard spindle length does not reach the arm connection point. It is most commonly needed when non-standard door or frame geometry shifts the mounting position beyond the standard spindle reach. If the track arm cannot be fully seated on the spindle during installation, the shaft extender is the correct solution.

Covers, Plugs, and Finish Hardware

• 4050AT-72MC: Metal cover for the closer body. The metal cover is the heavy-duty version and is specified in high-traffic or abuse-prone applications where the standard cover may not hold up.
• 4050AT-72: Standard cover for the closer body. Replace when the cover is cracked, missing, or no longer clips to the body correctly.
• 4050AT-141-1 plug and 4050AT-141-2 plug: Plugs that fill unused mounting holes in the closer body. Replace when plugs are missing and debris or moisture may enter the housing.
• 4050AT-73 end cap: The cap at the terminal end of the track extrusion that retains the roller assembly within the track travel range.

Screw Pack Selection Guide

The 4050AT uses different screw pack types depending on whether the installation is standard or hold-open, and depending on the substrate the track and closer are mounted to. Eight screw pack variants are stocked. Selecting the correct pack prevents the most common fastener mismatch on 4050AT service calls.

Complete LCN 4050AT Parts Reference

What Fails First on the LCN 4050AT

Most 4050AT service calls on high-cycle institutional doors fall into one of four failure patterns. Identifying the correct failure before ordering prevents double service calls and wrong-part returns.

Track Roller Wear

The track roller is the highest-wear component on most 4050AT installations. It experiences direct friction contact with the track rail on every door cycle. Roller wear is gradual on normal-cycle doors but accelerates when the door is forced manually against the closer, when the track has debris, or when the door panel is misaligned. Replace the roller when the door produces a grinding or thumping sound during the swing arc, or when the arm visibly skips in the track.

Track Rail Damage

The track rail can be bent or damaged by impact from door panels, carts, and equipment. A bent track causes the roller to bind mid-travel and the closer to stall before the door reaches the fully closed position. Inspect the track first when the door stops closing before latching and the closer itself is otherwise functioning.

Hold-Open Clip Failure

The hold-open clip is a wear component on doors that are routinely pushed to the fully open position and held there throughout the day. When the clip wears, the door no longer holds at the open position even though all other components are functional. Replace the clip before replacing the roller or track on hold-open function failures.

Arm Screw Loosening

The arm screw (4050AT-159) that connects the track arm to the closer spindle can loosen on high-cycle applications. A loose arm screw causes the arm to slip on the spindle, which typically produces a click or skip at the start of the opening cycle. Re-tighten or replace the arm screw before assuming the arm itself has failed.

Where to Source LCN 4050AT Parts

Security Parts stocks all 40 LCN 4050AT parts across arms, tracks, rollers, cylinders, plates, covers, and screw packs. Same-day shipping on stocked components. Call 845-935-0301 for pre-order compatibility support.

For guidance on scheduled inspection of door closers under NFPA 80, see the commercial door hardware maintenance checklist and the commercial door hardware replacement and repair guide.

For related LCN door closer parts, see the LCN 4040XP parts guide, the LCN 4000 series parts guide, and the door closers parts guide. For help selecting the correct LCN closer for a new installation, see the LCN closer selection guide and the door closer sizing guide.

For installation guidance, see how to install a commercial door closer. For adjustment after installation or replacement, see how to adjust a commercial door closer. For OEM versus aftermarket guidance, see the OEM vs aftermarket commercial door hardware guide.

About the Author

This guide was written by the Security Parts team, a commercial door hardware specialist serving locksmiths, facilities managers, general contractors, and access control integrators since 2001. Security Parts stocks the complete LCN 4050AT parts catalog across all arm, track, roller, cylinder, cover, and hardware configurations, with same-day shipping on stocked components and pre-order compatibility support at 845-935-0301.