Pulleys arrive either with a finished bore machined to a fixed shaft size or with a taper bore designed for taper lock bushes. Both are valid — the right choice depends on how many shaft sizes you support, how often pulleys are removed, and whether you prioritise inventory simplicity or maintenance flexibility. Most UAE MRO programmes standardise on taper lock for mixed shaft sizes and finished bore where bore never changes.
Finished bore pulleys
The bore and keyway are machined at the factory to your specified shaft diameter. Installation is direct: slide pulley on shaft, fit key, secure with set screw or collar as designed.
Best when shaft size is fixed across many identical machines — e.g. a fleet of same-model compressors all using 38 mm shaft with 14 mm keyway.
- Lower part count — no separate bush
- Fastest installation when bore exactly matches
- Must order exact bore — wrong size cannot be adapted easily
- Removal may require puller if tight fit
Taper lock pulleys
Hub has tapered bore; separate bush clamps onto shaft. One pulley OD/profile/groove SKU can serve multiple shaft sizes by changing bush.
Preferred for maintenance stores supporting varied equipment across a site — common in trading and project supply where exact shaft size varies by customer.
- Flexible bore via bush series change
- Easier removal using bush jacking screws
- Better concentricity when installed correctly
- Requires bush inventory alongside pulleys
Comparison table
| Factor | Finished bore | Taper lock |
|---|---|---|
| Bore flexibility | Fixed | Multiple via bush |
| Inventory | One pulley per bore | Fewer pulley SKUs, more bushes |
| Installation time | Fast if bore matches | Slightly longer |
| Removal for maintenance | Puller often needed | Jacking screws |
| Concentricity | Good if bore quality good | Very good when torqued correctly |
| Typical buyer | OEM repeat builds | MRO, retrofit, traders |
Pilot bore option
Pilot bore pulleys have undersized bore for user machining — useful for workshops that bore to exact size in-house. Confirm wall thickness and bore capacity before ordering pilot sizes for large bores.
Common mistakes
- Ordering finished bore without confirming keyway dimensions
- Reusing damaged taper bush after improper removal
- Mixing taper lock series between hub and bush
- Installing taper lock without cleaning taper surfaces