Taper lock bushes provide a concentric, removable connection between a shaft and a hub — pulley, sprocket, coupling, or gear. The tapered bore in the hub and matching taper on the bush create a mechanical shrink fit when cap screws are tightened, clamping the assembly onto the shaft. Correct installation ensures concentricity, full torque transmission, and easy future removal. Incorrect tightening is a common cause of runout, slippage, and damaged tapers in UAE maintenance workshops. This guide covers the full assembly and extraction procedure.
Components and how the taper lock works
A taper lock assembly consists of three parts: the hub (pulley, sprocket, or coupling half), the taper lock bush, and the cap screws. The bush has a tapered outer diameter that mates with a tapered bore in the hub. As cap screws are tightened, the bush is pulled into the hub taper, compressing the bush bore onto the shaft.
The friction between bush bore and shaft, combined with the key if fitted, transmits torque. The taper design allows the bush to be released by pushing it out of the hub taper using jacking screws — without damaging the shaft or hub.
- Hub — contains tapered bore and clearance holes for cap screws
- Bush — tapered OD, bored to shaft size, with threaded jacking holes
- Cap screws — pass through hub into threaded holes in bush, pull bush into taper
- Key (if fitted) — transmits torque, bush clamp provides friction grip
Pre-installation preparation
Clean all mating surfaces before assembly. Contamination on the taper surfaces prevents proper seating and causes runout. Remove any rust, paint, or old grease from the shaft, bush bore, and hub taper bore.
Confirm the bush size matches the hub taper bore series (e.g. 1210 bush in a 1210 taper bore hub). Confirm the bush bore diameter and keyway match the shaft. See the taper lock bush size chart in our belts and pulleys guides for bore-to-series matching.
- Clean shaft, bush bore, and hub taper with solvent or wire brush
- Verify bush series matches hub taper marking
- Confirm bore diameter and keyway match shaft
- Inspect cap screws — replace if worn, corroded, or stretched
- Apply light oil or anti-seize to taper surfaces (not shaft bore)
Installation procedure step by step
Insert the bush into the hub taper bore. Align the holes in the bush with the clearance holes in the hub — the bush should slide in by hand with no force. If it binds, check for incorrect bush series or debris in the taper.
Slide the hub-and-bush assembly onto the shaft to the approximate final axial position. Insert the key if fitted. Loosely fit all cap screws — do not tighten any single screw fully at this stage.
- Step 1: Insert bush into hub — align holes, hand-fit only
- Step 2: Slide assembly onto shaft with key in place
- Step 3: Loosely fit all cap screws (finger tight)
- Step 4: Tighten cap screws alternately in stages (see sequence below)
- Step 5: Tighten to recommended torque using a torque wrench
- Step 6: Verify no gap between bush flange and hub face
Tightening sequence and torque
Tighten cap screws in a star or cross pattern — alternating between screws rather than tightening one fully before moving to the next. This ensures even taper seating and prevents bush cocking in the hub bore.
Use at least three stages: first to 30% torque, then 60%, then 100% of the recommended final torque. Overtightening stretches cap screws and can crack the bush flange — undertightening allows slippage on the shaft.
| Bush series | Cap screw size | Typical torque (Nm) | Number of screws |
|---|---|---|---|
| 1008 | M6 | 8–10 | 2 |
| 1210 | M6 | 10–13 | 2 |
| 1610 | M8 | 20–25 | 2 |
| 2012 | M10 | 35–45 | 2 |
| 2517 | M10 | 45–55 | 2 |
| 3020 | M12 | 70–90 | 2 |
| 3535 | M12 | 90–110 | 3 |
| 4040 | M16 | 150–180 | 3 |
| 5050 | M20 | 250–300 | 3 |
Verification after installation
After final torque, check that the bush flange sits flush against the hub face with no visible gap. A gap indicates the bush is not fully seated in the taper — recheck cap screw torque and taper cleanliness.
Measure runout on the hub OD or groove face if precision is required (e.g. pulley groove runout affects belt tracking). Excessive runout after correct installation may indicate a damaged taper, wrong bush series, or bent shaft.
- No gap between bush flange and hub face
- All cap screws at full recommended torque
- Hub rotates freely on shaft with no axial play
- Runout check on pulley groove or coupling hub if precision required
Removal procedure
Remove all cap screws from the hub. The cap screws pass through clearance holes in the hub into threaded holes in the bush — these same threaded holes serve as jacking (extraction) holes during removal.
Thread the cap screws into the jacking holes in the bush (the holes that were covered by the hub clearance holes). Tighten evenly and alternately — the screws push against the hub face and drive the bush out of the taper bore. The assembly will loosen from the shaft once the taper disengages.
- Remove all cap screws from hub
- Thread cap screws into bush jacking holes
- Tighten jacking screws evenly and alternately
- Bush pushes out of hub taper — assembly slides off shaft
- Never pry with levers against hub or bush — damages taper surfaces
Troubleshooting stuck assemblies
If the bush will not release with jacking screws, apply penetrating oil to the taper joint and allow soak time. Light tapping with a soft mallet on the hub (not the bush) while jacking can help break corrosion bonds.
In extreme cases where the bush is seized due to corrosion or previous overtightening, heat the hub (not the shaft) gently with a heat gun to expand the hub bore. Never use a cutting torch on taper surfaces — warpage ruins the concentric fit.
If jacking screw threads are stripped, use a puller or carefully apply uniform pressure around the bush flange. Never hammer the bush directly — this damages the taper and the bore.
- Penetrating oil soak before jacking
- Heat hub (not shaft) if corrosion-seized
- Never pry with screwdrivers or levers — damages tapers
- Never cut bush with torch or grinder while on shaft
- Replace cap screws if threads are damaged during extraction
Common mistakes to avoid
- Tightening one cap screw fully before others — causes bush cocking and runout
- Omitting the key and relying on friction alone for high-torque applications
- Using the wrong bush series in a hub — similar tapers may partially fit but will not clamp
- Overtightening cap screws beyond recommended torque — stretches screws and cracks bush
- Installing on a shaft with incorrect diameter — undersized shaft causes slippage, oversized prevents seating
- Prying bush out with levers — gouges taper surfaces, ruining concentricity
- Reusing damaged or stretched cap screws after multiple removal cycles
- Skipping taper surface cleaning — debris causes incomplete seating and runout
RFQ checklist
- Bush series matches hub taper bore (e.g. 2012 in 2012 hub)
- Shaft diameter and keyway confirmed
- Cap screws present, correct size, and in good condition
- Taper surfaces cleaned and lightly oiled
- Torque wrench available for final tightening
- Jacking screws tested — cap screws fit jacking holes for future removal
- Runout check planned if precision drive (pulley, high-speed coupling)