LiftMaster K75-19985 Clutch Pulley Assembly — Specified Commercial-Operator Drives

The LiftMaster K75-19985 is the clutch pulley assembly identified in documented commercial-operator service drawings, including the Model J drive. It is a separate service component within the clutch-shaft arrangement, distinct from the motor pulley, belt and complete clutch-shaft kit. Match the exact operator generation and drive position before ordering rather than choosing from the word pulley or approximate diameter alone. Select the replacement by the complete part number and the installed equipment configuration. A similar photograph or a shared LiftMaster brand name does not establish interchangeability. Confirm the applicable service drawing before ordering so the repair addresses the correct component and its related mounting, connection and operating requirements.

Compatibility — Models, Versions and Exclusions

Identify the Assembly and Plan the Repair

Identify the pulley’s location and inspect the belt, mating shaft and clutch components. A worn belt, unsuitable alignment or damaged shaft can cause drive symptoms that remain after a pulley-only replacement. Determine whether damage is limited to the assembly or whether the larger clutch-shaft grouping is needed.

Preserve the approved belt-drive and clutch relationship. Do not transfer bore dimensions, groove profiles or supplied hardware from a different pulley listing. Follow the exact service procedure for retention, alignment and any clutch adjustment. Increasing clutch force or belt tension is not an appropriate way to overcome a door that is difficult to move.

Compare the replacement with the installed service arrangement before dismantling the equipment. Photograph the part’s location and record the complete model and visible service numbers. Inspect the surrounding attachment points and mating components for wear, impact damage or misalignment. Replacing one worn item will not correct a damaged support or another component that continues to impose abnormal loads on the repaired assembly.

Plan the repair around the manufacturer’s instructions for the actual equipment revision. Confirm access, safe support and any separate hardware before removing the old part. After installation, restore the intended retention, alignment and guarding, then test the equipment under controlled conditions. The repair is complete only when the original fault has been addressed and the system’s required operating and protection functions have been checked.

Specifications and Product Identification

Before Ordering

• Confirm the full operator and clutch revision.
• Locate K75-19985 in the exact drawing.
• Inspect belt, shaft and adjoining clutch pieces.
• Compare the individual assembly with a larger kit requirement.

Package Contents and Separate Requirements

This offer identifies the pulley assembly. Belt, motor pulley, clutch shaft, bearings, clutch disc, motor and complete operator are separate unless explicitly included. Confirm the supplied assembly and small retention pieces with the current carton. The larger clutch-shaft kit’s inventory does not automatically apply to this individual pulley order.

Safety Warnings — Read Before Installation or Service

• WARNING: A moving commercial door and exposed clutch pulley assembly — specified commercial-operator drives can cause serious injury or death. Have a trained door-systems technician perform installation and service.
• Disconnect mains power and any battery backup before mechanical work or wiring. Secure the door against unexpected movement as directed by its manufacturer.
• Do not work on springs, cables or counterbalance components without appropriate training. Never bypass safety sensors or increase force to overcome binding.
• Restore guards and complete the model-specific travel, reversal and protection-device tests before returning the door to normal operation.

Related Products and Important Differences

• CPS-U monitored photo eyes — separate protection devices for approved commercial-door controls; match the operator and environment.
• TDC12X1BMC MAXUM trolley operator — a complete-operator comparison, not evidence that this legacy service part fits MAXUM.

Frequently Asked Questions

Is it the motor pulley?

No. The documented arrangement identifies that separately.

Does it include the complete clutch shaft?

No complete shaft kit is promised here.

Can it fix an incorrectly balanced door?

No. Door balance and binding need qualified service.

May I use another similar-sized pulley?

Do not substitute without verified shaft, belt and drive compatibility.

Need Help Confirming the Right Product?

Contact Garage-DoorParts.com before ordering. Send the full equipment model, readable part labels and photographs of the installed assembly. Include the dimensions, electrical configuration or accessory details relevant to your project so the listing can be checked against the actual installation.