LiftMaster K12-10458 Limit-Shaft Flange Bearing — 3/8-Inch Designation

The LiftMaster K12-10458 is the flange-bearing service component identified with a 3/8-inch designation and used in the specified limit-shaft arrangement. The supplier also associates historical references 12-10458 and 12-9031. Confirm the complete shaft and housing fit from the operator drawing; a matching nominal diameter does not establish every bearing or mounting dimension. 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

A bearing must fit both the shaft and the supporting housing. Inspect the shaft surface, mounting hole and neighboring limit-drive components before selecting a bearing-only repair. A new bearing cannot correct a worn shaft or an enlarged support that allows the limit mechanism to move out of position.

Limit-system work can affect where the door stops, even when the replacement is a small mechanical part. Record the original assembly location and obtain the exact service procedure. Restore shaft retention and drive alignment, then verify the required travel settings and protection functions after reassembly.

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.

Specifications and Product Identification

Before Ordering

• Record the complete operator and limit assembly.
• Match K12-10458 and the 3/8-inch designation.
• Inspect shaft and support fit for wear.
• Confirm current bearing inventory and final limit checks.

Package Contents and Separate Requirements

This offer identifies the flange-bearing service item. A complete limit shaft, sprocket, limit nuts, switches, retention hardware and operator are not established as included. Confirm current supplied pieces and obtain other worn limit components separately where required.

Safety Warnings — Read Before Installation or Service

• WARNING: A moving commercial door and exposed limit-shaft flange bearing — 3/8-inch designation 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

Does 3/8 inch prove the bearing will fit?

No. Shaft fit, flange geometry, housing fit and the exact approved service reference must all match.

Is a complete limit mechanism included?

No. This is the individual bearing service component.

Will it repair a worn shaft?

No. Inspect the shaft and support and correct other damage as needed before fitting the bearing.

Should travel limits be checked afterward?

Yes. Follow the equipment-specific procedure and verify stopping positions and all required protection functions after limit-drive service.

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.