LiftMaster K20-1050B-1RSX Replacement AC Gate Motor — 1/2 HP

The LiftMaster K20-1050B-1RSX is a half-horsepower AC replacement motor identified in documented LiftMaster gate-operator repair drawings. It is a service component for the matching motor and drive arrangement, including the documented CSW200501U swing and SL3000501U slide applications. Select it by the existing motor label and the exact operator revision, not simply by the CSW200 or SL3000 family name. Those families include different horsepower configurations, and a shared manual or similar motor appearance does not make this half-horsepower motor an approved replacement for a one-horsepower unit.

Compatibility — Models, Versions and Exclusions

Match the Motor and Diagnose the Complete Drive

Record the full operator model and the label on the installed motor, including its electrical information. Compare the mounting, shaft connection and associated drive components with the applicable repair drawing. A generic half-horsepower rating is only one selection factor; it does not verify voltage, rotation, mounting or the correct connection arrangement for the equipment being repaired.

Have the technician evaluate the power supply, capacitor where fitted, wiring and mechanical drive before replacing the motor. A motor that hums, overheats or fails to start can be responding to another fault. Check that the gate moves freely and that the gearbox, pulley or other connected components are serviceable. A new motor will not correct a binding gate or damaged transmission.

Specifications and Product Identification

Before Ordering

• Record the full operator model, production revision and existing motor label.
• Confirm the required motor is the documented half-horsepower K20-1050B-1RSX.
• Check the supply, starting components and mechanical drive before ordering.
• Verify the current motor package and any separately needed mounting or drive hardware.

Package Contents and Separate Requirements

This listing identifies the replacement motor. A pulley, belt, capacitor, brake, gearbox, wiring harness or complete operator is not promised as included. Confirm the current supplier package against the repair requirements. A parts illustration may show the motor beside these components without including them in the motor carton. Retain only hardware that the service instructions permit to be reused and that the technician finds serviceable.

Safety Warnings — Read Before Installation or Service

• WARNING: Motor service exposes hazardous electrical components and a drive that can move the gate unexpectedly. Use a qualified gate-systems technician and qualified electrical personnel as required.
• Isolate all applicable power and secure the gate before disturbing the drive. Capacitors may retain energy after power is disconnected; follow the manufacturer’s service procedure.
• Do not substitute an unverified voltage, change drive ratios or increase force to overcome binding. Never bypass required entrapment protection.
• Restore guards, verify the prescribed motor and drive operation, and test travel, reversal and all required safety devices before normal use.

Related Products and Important Differences

• LMRRUL monitored photo eye — a separate protection option only where the exact operator and control revision approve it; not a universal legacy retrofit.
• LMWEKITU monitored wireless edge kit — a separate edge communication system for approved controls and resistive edges; not a replacement for this mechanical or electrical service part.

Frequently Asked Questions

Is this a one-horsepower replacement motor?

No. The published identification is one-half horsepower. Do not rely on a shared family manual to infer one-horsepower compatibility.

Can any half-horsepower motor replace it?

No. The approved part reference, electrical requirements, mounting and drive connection must all match.

Does the motor include the capacitor or gearbox?

Neither is promised as included. Confirm the current carton and order separately required components.

Will replacing the motor fix a gate that binds?

No. Diagnose and correct the mechanical problem before returning the drive to operation.

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.