Liftmaster K75-19478 Sprocket, 48B32T, 1-1/2"B
The LiftMaster K75-19478 listing is for a 48B32T sprocket with a 1-1/2 in. bore used in heavy commercial operator drive hardware. In these operators, the sprocket is part of the mechanical drive train that transfers motor and shaft movement through the chain and clutch area. A worn or damaged sprocket can create chain jumping, noise, uneven travel, metal wear, poor release action, or repeated chain adjustment problems.
During the deep search, this item showed a possible old-number or listing conflict. The uploaded row identifies the part as K75-19478, while multiple replacement-parts references for the same 48B32T, 1-1/2 in. bore sprocket describe K15-19478 or 15-19478. Because these numbers are close and the physical description is similar, the page copy keeps K75-19478 as the sold item but clearly lists K15-19478 / 15-19478 as related numbers that must be verified before substitution.
This sprocket should be matched by part number, tooth count, bore size, and operator diagram. Do not assume that every 48B32T sprocket will fit the same shaft or chain position. Commercial LiftMaster H, J, and HJ operator frames can share similar mechanical layouts while using different shaft, sprocket, frame, and disconnect combinations.
Compatible With
Compatibility is intentionally cautious because the uploaded K75-19478 number closely overlaps with K15-19478 / 15-19478 references.
- Select LiftMaster commercial hoist and jackshaft operator drive assemblies where K75-19478 is listed by the stock label or parts diagram.
- Related LiftMaster H, J, and HJ commercial operator diagrams where 15-19478 or K15-19478 is shown as a 48B32T, 1-1/2 in. bore sprocket assembly.
- Post-2005 style LiftMaster Jackshaft and Hoist commercial door operators where the exact 48B32T, 1-1/2 in. bore sprocket is specified.
- Model H commercial hoist operator families only when the diagram calls for the matching sprocket location and bore.
- Model J commercial jackshaft operator families only when the diagram calls for the matching sprocket location and bore.
- Model HJ hoist/jackshaft operator families only when the diagram calls for the matching sprocket location and bore.
- Not recommended as a substitute for 48B18x1 in., 50B12x1 in., or other sprockets with different tooth count, chain pitch, or bore size.
Also Known As / Related Part Numbers
- K75-19478
- 75-19478
- K15-19478 - related 48B32T 1-1/2 in. bore reference, verify before substitution
- 15-19478 - related sprocket assembly reference, verify before substitution
- 48B32T
- 48B32T 1-1/2 in. bore sprocket
- Sprocket Assembly 15-19478
- Related nearby diagram parts: 15-48B18LGE, 15-50B12LGH, 16-5L304 cogged belt
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster / Chamberlain |
| Product Type | Commercial operator sprocket |
| Part Number | K75-19478 |
| Sprocket Size | 48B32T |
| Bore | 1-1/2 in. |
| Application | Commercial operator drive sprocket / sprocket assembly area |
| Compatible Operator Type | Select LiftMaster hoist and jackshaft commercial door operators |
| Related Number Caution | K15-19478 and 15-19478 are closely related references; verify before substituting |
| Notes | Match tooth count, bore, shaft location, and parts diagram |
Technician Note
Sprocket replacement should include an inspection of the chain, shaft, key, bearings, clutch hardware, and adjacent sprockets. If the chain has been running out of alignment, installing a new sprocket without correcting the shaft or frame issue can quickly damage the replacement part.
Before Ordering
- Verify whether the stock label says K75-19478, K15-19478, or 15-19478.
- Confirm 48B32T tooth count and 1-1/2 in. bore before ordering.
- Check operator model and parts diagram for the exact sprocket position.
- Do not substitute for 48B18, 50B12, or another bore size.
- Inspect the chain and shaft key before putting the operator back in service.
Professional Advisory
Commercial door operator mechanical parts should be installed with the operator power disconnected and the door properly secured. Do not service a hoist, jackshaft, slide gate, or industrial door operator that has a damaged door, broken spring, unsafe counterbalance, missing entrapment protection, or uncontrolled movement. Use a qualified commercial door or gate technician when alignment, high-voltage wiring, brake work, or operator safety devices are involved.
Product Questions & Answers
The uploaded part number is K75-19478, but many parts references for the 48B32T, 1-1/2 in. bore sprocket show K15-19478 or 15-19478. The numbers should be compared to the stock label and parts diagram before ordering.
Is this sprocket interchangeable with other 48B sprockets?
Not automatically. Tooth count, bore size, shaft location, keyway, and operator diagram must match.
What operators commonly use this sprocket style?
It is commonly associated with select LiftMaster commercial hoist and jackshaft operator drive assemblies, especially H, J, and HJ style diagrams when the sprocket number is listed.
Should the chain be replaced with this sprocket?
Replace or adjust the chain if it is stretched, rusted, damaged, or has been running out of alignment. A worn chain can damage a new sprocket.
Can this be used on a gate operator?
Only if the gate operator parts diagram calls for this exact sprocket number. Do not use it as a generic gate operator sprocket.
