Taper Lock Bushes

Taper-lock bushes are the workshop-standard way to mount pulleys, sprockets and couplings onto shafts in industrial power transmission. The bush slides onto the shaft, the pulley or sprocket fits over the bush's tapered outer surface, and two or three hex bolts pull the bush home — the taper compresses against the shaft and locks the assembly without a press fit, machined keyway in the bush, or set screws marking the shaft. Done properly, the joint runs concentric, transmits torque cleanly, and pulls apart in minutes when a belt change or maintenance job comes due. AIMS Industrial supplies the taper-lock series most commonly specified across Australian industry — 1008 up to 5050 — in metric and imperial bores, broached and unbroached, ready to suit the hub you're matching.

Taper-Lock Bush Series Reference

Each series has a fixed outside diameter, axial width, and bolt pattern. The bush series is dictated by the mating pulley or sprocket — not by your shaft. The shaft determines the bore size within that series.

[VERIFY:] Torque values are typical for the original Fenner pattern. Always confirm the figure stamped on the bush face or in the manufacturer's data sheet before final tightening — Optibelt, Gates, and other suppliers occasionally publish slightly different values for the same series.

How Taper-Lock Bushes Work

The bush is a sleeve with a tapered outside surface and a longitudinal slit. The mating hub (pulley, sprocket, coupling) has a matching internal taper bored to the same series. When you tighten the cap screws, they pull the bush deeper into the hub's taper. The slit lets the bush compress radially as the taper draws home, so the bore grips the shaft tightly while the OD wedges against the hub. The result is a friction joint with no slop — the bush, the hub, and the shaft all rotate as one.

Torque on the cap screws is what generates the clamping force. Under-torque and the joint slips under load. Over-torque can split the bush or distort the hub. Manufacturer torque values are not suggestions — they're calculated to give the friction joint its rated torque-transmission capacity.

Reading the Bush Designation

Taper-lock bush part numbers are a compact code. The first two digits give the OD (in tenths of an inch, originally), and the second two give the axial width. Examples:

• 1008 — 1.0" nominal OD, 0.8" width. Smallest common series.
• 1610 — 1.6" nominal OD, 1.0" width. The general industrial workhorse.
• 2517 — 2.5" nominal OD, 1.7" width. Medium-heavy.
• 3030 — 3.0" nominal OD, 3.0" width. Heavy, wider for multi-strand sprockets.
• 5050 — 5.0" nominal OD, 5.0" width. Heaviest standard taper-lock.

Once you know the series from the mating hub, you only need to specify the bore — metric (e.g. 24mm, 32mm, 50mm) or imperial (e.g. 1", 1-1/4", 1-3/4") — and whether the keyway is required broached to AS 2938 (standard parallel key) or unbroached for a clean shaft.

Bore Options

Most series cover a wide bore range from a few millimetres below their nominal up to the listed max bore. Standard stock options:

• Metric bores — 10mm increments below 30mm, then 1mm or 2mm steps up to max bore. AS 2938 parallel keyway as standard.
• Imperial bores — 1/16" or 1/8" steps. Standard imperial keyway dimensions.
• Unbroached — no keyway, for shafts that are non-keyed or where the friction grip alone is enough (some lighter drives).
• Special / made-to-order — odd bores, non-standard keyway sizes, or stainless-steel bushes for food and corrosive environments. Contact us for a quote.

Installation Procedure

1. Clean every mating surface. Wipe the shaft, the bush bore, the bush OD, and the hub taper bore with a clean rag and degreaser. Any debris, oil, paint, or burrs left in the taper bore will reduce friction grip and the assembly will slip under load. This is the single most common cause of taper-lock failure.
2. Check the bolt holes line up. Bush bolt holes are half-threaded, hub bolt holes are clearance — when assembled correctly, the bolts pass through the hub and thread into the bush. There are also unthreaded pull-off holes (1, 2, or 3 depending on series) used only for removal.
3. Slide the bush onto the shaft. Position so the flange end is where the manufacturer specifies (usually toward the hub face for standard mounting).
4. Fit the hub over the bush. Align the bolt holes between hub and bush.
5. Insert the cap screws and finger-tighten. Use only the bolts supplied with the bush (length is set to match bush width) — wrong-length bolts will bottom out before the bush is properly seated.
6. Tighten progressively in cross-pattern. Apply about half the final torque to each bolt in sequence, then bring all bolts up to full torque (see series table above). Tap the hub face lightly with a soft mallet between passes — this helps the taper seat fully.
7. Re-check torque after 24 hours of running. Heat cycles and initial bedding-in can relax the joint slightly; a torque re-check on commissioning is good practice.

Removal Procedure

1. Remove all cap screws completely. Don't leave any in the threaded holes.
2. Move the bolts to the pull-off holes. Each series has unthreaded holes (typically 1 on small bushes, 2 or 3 on larger) that act as jacking points. Insert the cap screws into these holes — they'll thread into the hub and push against the bush face.
3. Tighten the pull-off bolts alternately. The bush will release from the hub taper and slide free on the shaft.
4. If the bush is stuck — apply penetrating fluid, allow to soak, and try again. For severely stuck bushes, mild heat applied to the hub (not the bush) can help. Never strike the bush with a hammer or drift to free it — you'll deform the slit and ruin the bush.

Torque Specifications

Torque values vary by manufacturer and series. The figures in the reference table above are typical for the original Fenner taper-lock pattern and are flagged [VERIFY:] because Optibelt, Gates, and other quality suppliers occasionally specify slightly different torques. Always:

• Read the figure stamped or printed on the bush face.
• Cross-check the manufacturer's data sheet if the bush face is unmarked.
• Use a calibrated torque wrench — guess-tightening with a regular spanner is the second-most-common cause of taper-lock failure (after dirty mating surfaces).

Under-torqued bushes slip and chew the shaft. Over-torqued bushes split — the longitudinal slit acts as a stress-concentration point, and excessive bolt force can crack a cast-iron bush.

Common Applications

• V-belt sheaves — Classical A/B/C, narrow SPZ/SPA/SPB/SPC, and Banded multi-section pulleys on motor drives, fans, blowers, and pumps. See our V-pulley range.
• Synchronous timing pulleys — HTD, GT, and Poly Chain GT carbon-belt drives where positive engagement is required. See timing pulleys.
• Roller chain sprockets — ANSI and BS series sprockets on conveyors, gearboxes, and industrial drives. See sprockets.
• Couplings — Flexible couplings, jaw couplings, and tyre couplings where the hub is bored to a taper-lock series. See couplings range.
• Fans and blowers — Industrial fan impellers mounted on motor shafts via taper-lock sheaves.
• Pump drives — Belt-driven centrifugal and positive-displacement pumps.

Brand Range

The taper-lock standard is interchangeable — a 2517 bush from one manufacturer fits a 2517-bored hub from another. AIMS supplies taper-lock bushes through our broader power-transmission ranges, including:

• Finer Power Transmissions — quality Australian-distributed taper-lock range, standard and special bores.
• Gates — taper-lock sheaves and bushes matched to Gates belts and Poly Chain GT carbon drives.

Other quality brands (Fenner, Optibelt, Falk) can be sourced on request — contact our team if you need a specific brand or have a hub already specified to a particular manufacturer.

Companion Components

Taper-lock bushes are one part of the drive assembly. The hub and the shaft side also need attention:

• V-pulleys — Classical, narrow, and banded V-belt sheaves with taper-lock bored hubs.
• Timing pulleys — Synchronous belt pulleys for HTD, GT, Poly Chain GT, and classical timing belt drives.
• Sprockets — Roller chain sprockets with taper-lock bores in ANSI and BS sizes.
• Couplings — Flexible, jaw, and tyre couplings with taper-lock bored hubs.
• Pulleys — Full pulley range across V-belt, timing, and idler types.
• Belts — V-belts, timing belts, and Poly Chain GT carbon belts to match the drive.
• Key steel — Parallel key stock in metric and imperial sizes to AS 2938 for keyway-broached bushes.
• Locking assemblies — Higher-torque shaft-to-hub locking devices for applications where taper-lock isn't sufficient.
• Roller chain — ANSI and BS roller chain to complete sprocket drives.

AIMS' Note on Taper-Lock Selection

If you're matching a bush to an existing pulley or sprocket, the series is set — read the bush series stamped on the hub face or measure the existing bush. If you're specifying a new drive from scratch, the pulley or sprocket catalogue will list the available taper-lock series for each size. From there it's just bore selection.

When you contact us for taper-lock bushes, the four things we need are:

• Series (e.g. 1610, 2517, 3020).
• Bore size in mm or inches.
• Keyway — broached to AS 2938 standard, broached imperial, or unbroached.
• Application — what the bush is driving (helpful for cross-checking the series and bore are sensible for the torque and speed involved).

For straightforward off-the-shelf bushes in the common series and bore sizes, ordering online is the fastest path. For non-standard bores, stainless steel, or unusual series, ring our team — same-day quote and we'll work through the supplier options.

Companion Resources

• Taper Lock Bush Guide: Sizes, Installation & Removal — full installation walk-through with photos.
• Pulley Types Guide: V-Belt Sheaves, Taper Lock & Selection — pulley selection reference.
• Pulley Speed Ratio Calculator & Formula Explained — drive ratio calculation.
• V-Belt Problems & Solutions: Symptom-Cause-Fix Guide — diagnosing belt-drive faults.
• Belt vs Chain Drives: Selection by Application & Trade-Offs — choosing between belt and chain drive.
• Bearings & Power Transmission Guide: Types & Selection — the broader drivetrain context.
• Keyways & Keys: Parallel Keys, Woodruff Keys, Key Steel & Size Charts — keyway dimensions to AS 2938.

Need help matching a bush series, bore, or drive setup? Contact our team — phone, email, or web form, we'll get you the right part.