Liftmaster 129050 Flange Bearing, 1"
The LiftMaster K12-19504 is a 1 inch flange ball bearing used as a replacement support bearing in select LiftMaster commercial door operator assemblies. A flange bearing helps support and guide a rotating shaft so sprockets, pulleys, chains, and other drive components stay aligned while the operator is under load.
This bearing is commonly cross-referenced with 6001957, 1210715, G129050, and 129050. Those numbers may appear in older parts diagrams, service notes, or supplier listings. Since commercial door operators can use multiple bearing sizes in the same general product family, the best match is made by checking the original bearing marking, shaft size, flange shape, bolt spacing, and operator parts diagram.
Compatible With
Common Compatible Applications
- Select LiftMaster commercial door operators that call for a 1 inch flange ball bearing
- Commercial door operator drive assemblies using K12-19504 or one of its related bearing references
- Applications where the original bearing is marked or cross-referenced as 6001957, 1210715, G129050, or 129050
Important Compatibility Notes
- This is not a universal 1 inch bearing for every LiftMaster operator.
- Verify shaft diameter, flange style, mounting hole pattern, and overall bearing profile.
- Do not substitute a bearing with a different bore, load rating, or mount pattern.
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster |
| Product Type | Flange ball bearing |
| Part Number | K12-19504 |
| Bearing Size | 1 inch bore |
| Application | Commercial door operator shaft support / drive assembly bearing |
| Compatible Operator Type | Select LiftMaster commercial door operators |
| Related References | 6001957, 1210715, G129050, 129050 |
| Notes | Match by bearing size, flange style, bolt pattern, and parts diagram |
Also Known As / Related Part Numbers
- K12-19504
- LM-K12-19504
- 6001957
- 1210715
- G129050
- 129050
- LiftMaster 1 inch flange bearing
- LiftMaster flange ball bearing 1 inch
Technician Note
If the old bearing failed, check the shaft for wear and inspect any sprocket, pulley, chain, or belt running on that shaft. A new bearing may fail early if the shaft is damaged or the drive assembly is misaligned.
Before Ordering
- Confirm the bearing bore is 1 inch.
- Match the flange style and mounting hole spacing to the original bearing.
- Check the parts diagram for K12-19504 or one of the related numbers.
- Inspect the shaft for scoring, rust, or looseness before installing the new bearing.
- Do not reuse bent or worn mounting hardware if it prevents the bearing from sitting flat.
Professional Advisory
Commercial door operator repairs can involve heavy doors, spring tension, and electrical components. Secure the door and disconnect power before service. Use a qualified commercial door technician if shaft alignment, spring balance, or electrical diagnosis is involved.
Product Questions & Answers
What size is the K12-19504 bearing?
K12-19504 is listed as a 1 inch flange ball bearing.
What part numbers are related to K12-19504?
Common related references include 6001957, 1210715, G129050, and 129050.
Is this bearing for gate operators or commercial door operators?
The strongest references list it for select LiftMaster commercial door operators. Always verify by the exact equipment parts diagram.
What are signs of a worn flange bearing?
Common signs include shaft movement, grinding noise, uneven sprocket or pulley tracking, metal dust, or vibration during operation.
Can any 1 inch bearing replace this part?
No. The bore, flange style, bolt spacing, load rating, and operator application must match the original bearing.
