A taper lock bush is one of the most widely used shaft mounting systems in Australian industry — and one of the least understood. Millwrights and maintenance engineers fit them daily on conveyor drives, fan pulleys, pump sheaves, and chain sprockets. But incorrect installation, wrong shaft tolerance, and seized removal are recurring problems that cost far more in downtime than the bush itself.

This guide covers everything: how the 1:12 taper generates its clamping force, decoding the 1008 to 5050 size series, the correct installation and removal sequence, steel versus cast iron selection, and how taper lock bushes compare to QD bushes and keyless alternatives. AIMS Industrial stocks taper lock bushes across all major series — browse the full range here.

What Is a Taper Lock Bush and How Does It Work?

A taper lock bush is a split, tapered sleeve that clamps a power transmission component — pulley, sprocket, sheave, or coupling — onto a shaft. The outer diameter is machined to a 1:12 taper that matches the tapered bore of the hub. The bush is split longitudinally so it can contract slightly when the fixing screws are tightened, generating a high radial clamping force on the shaft and an equal axial force locking the bush into the hub.

The 1:12 taper ratio (approximately 4.76° included angle) is a self-locking geometry. Once the bush is driven home, it stays in place without relying solely on screw pre-load. This is the same principle as a Morse taper in a lathe spindle, but applied to a removable, torque-transmitting joint. The standard governing the dimensional series is BS 4235 Part 2 — all reputable manufacturers conform to this, which means bushes from different suppliers are dimensionally interchangeable across the same series.

Torque is transmitted through a parallel key seated in matching keyways cut in both the bush bore and the shaft. The bush bore and keyway are finish-machined to specified tolerances so the key bears against both faces simultaneously. Without a correctly fitted key, the bush transmits only friction — and friction alone is generally insufficient for sustained industrial loads.

The Taper Lock system was originally developed and patented by Fenner Drives and has been the European and Australian industrial standard for shaft-hub connections since the 1950s. Today, all major power transmission suppliers — Rexnord, SKF, Gates, Fenner, TB Wood's — produce dimensionally interchangeable taper lock bushes to BS 4235 Part 2.

Taper Lock Bush Sizes: Decoding the 1008 to 5050 Series

Every taper lock bush carries a four-digit designation that encodes its size class. Understanding the numbering system is essential for correct selection — choosing the wrong series for a hub is a common ordering mistake that results in unusable stock.

How to read the number: The first two digits approximate the maximum bore diameter (in millimetres ÷ 10); the last two digits give the bush length in millimetres. A 2517 bush: maximum bore ≈ 75 mm, length = 44 mm (the nominal 17 approximates, not equals, the bore dimension in this series).

In practice, use the table below. Do not rely solely on the arithmetic — always cross-reference the series against the actual bore range specified by the manufacturer.

Series	Min. Bore (mm)	Max. Bore (mm)	Bush Length (mm)	Fixing Screws	Screw Size	Typical Applications
1008	9	25	21	2	M6	Small fans, light conveyors, sensor drives
1108	9	28	21	2	M6	Light-duty pump drives, small pulleys
1210	9	32	25	2	M8	Fan drives, small conveyor pulleys
1215	9	32	38	2	M8	Wider hubs, same bore range as 1210
1310	9	35	25	2	M8	HVAC fan pulleys, light conveyor drives
1610	14	50	42	3	M8	General industrial — most common small series
2012	14	55	30	3	M10	Pump and compressor drives
2517	15	75	44	3	M10	Conveyor head pulleys, medium fan drives
3020	19	85	51	3	M12	Heavy conveyor drives, industrial fans
3030	19	85	76	3	M12	Wide-hub version of 3020 — high torque applications
3525	25	100	64	3	M16	Large conveyor drives, crusher drives
4030	35	120	76	4	M16	Heavy industry — mining, quarrying
4040	35	120	102	4	M16	High-torque version of 4030
4535	40	140	89	4	M20	Large industrial drives
5040	50	160	102	4	M20	Heavy mining, cement, and steel plant drives
5050	50	160	127	4	M20	Maximum-series — high torque, wide hub requirement

Shaft Tolerances and Keyways: What You Need Before Fitting

Getting the shaft prepared correctly before the bush goes on is the single most effective way to prevent problems in service. Two things must be right: the shaft diameter tolerance, and the keyway geometry.

Shaft diameter tolerance

BS 4235 Part 2 specifies h8 as the recommended shaft tolerance for taper lock bushes. This is a clearance-to-zero tolerance — the shaft is at or slightly below the nominal diameter, allowing the bush to slide onto the shaft by hand and seat correctly before the screws are torqued. A shaft ground to h6 or h7 is also acceptable and gives a marginally snugger pre-fit.

Do not use taper lock bushes on shafts with interference tolerances (k6, m6, p6). The bush cannot be pushed onto an interference-fit shaft without damaging the taper surface — and if it can be forced on, it will be nearly impossible to remove without damaging both the bush and the shaft.

Shaft Tolerance	Fit Type	Taper Lock Compatibility	Notes
h6	Slight clearance to zero	✅ Preferred	Ground shaft — optimal surface finish and dimensional control
h7	Clearance to zero	✅ Acceptable	Standard turned/ground shaft — good for most applications
h8	Clearance	✅ Standard per BS 4235 Pt 2	Minimum recommended — allows hand assembly without force
h9, h11	Wide clearance	⚠️ Use with caution	Shaft undersized — bush may not generate full clamping force
k6, m6, p6	Interference	❌ Not compatible	Bush cannot be fitted; if forced, cannot be removed

Keyway requirements

The keyway in the shaft must be machined to ISO 773 / BS 4235 dimensions for the relevant bore size. The key must be a close sliding fit in the keyway — not a hammer fit, not a loose rattle fit. A key that requires hammer driving to seat will generate asymmetric clamping forces across the bush bore and can cause the hub to run out-of-true.

Parallel keys are standard for taper lock applications. Woodruff (half-moon) keys are not used — the milling required for a Woodruff keyway removes more shaft cross-section and is unnecessary for this application.

How to Install a Taper Lock Bush: The Correct Sequence

Taper lock installation is straightforward when the sequence is followed precisely. Deviations — particularly tightening screws in one pass, or skipping the cross-tightening sequence — result in uneven seating, reduced clamping force, and eventual slip.

1. Clean all mating surfaces. Degrease the bush taper, the hub bore, the shaft, and the key with a clean solvent (acetone or brake cleaner). The joint must be metal-to-metal clean — no oil, no grease, no residual cutting fluid.
2. Check the bush for free rotation in the hub. Before fitting the shaft, insert the bush into the hub bore by hand and confirm it can rotate freely without resistance. If it binds, the taper bore may be damaged or contaminated — do not proceed until resolved.
3. Fit the key. Insert the parallel key into the shaft keyway. The key should slide in with hand pressure and sit flush or 0.1–0.3 mm above the shaft diameter at most.
4. Apply a light coat of machine oil to the shaft bore of the bush only. Do not oil the taper or the hub bore.
5. Slide the bush onto the shaft and align the keyway in the bush bore over the key. The bush should slide on without resistance to approximately the correct axial position.
6. Position the hub + bush assembly on the shaft at the required axial location. For pulleys and sheaves, this is typically the centreline of the drive face aligned with the belt or chain.
7. Insert the fixing screws finger-tight into the installation holes (tapped holes). Do not put any screws in the extraction holes at this stage.
8. Tighten the screws progressively in a cross pattern. Three passes: first to 25% of final torque, second to 60%, third to full specified torque. Refer to the manufacturer's datasheet for the specific torque value for the series.
9. Check runout with a dial indicator. Acceptable runout for most industrial drives is ≤ 0.05 mm TIR. If excessive runout is present, the key may be oversized or the hub bore may be off-centre — remove and investigate.
10. Re-torque after initial service run. After 24–48 hours of operation, retorque all fixing screws to the specified value. New bushes bed in slightly during initial running and screw pre-load can relax by 10–15%.

Why There Are Fewer Screws Than Holes

Every maintenance engineer eventually notices that a three-hole taper lock bush comes with only two screws. This is not a missing-parts problem. It is a deliberately engineered feature of the Taper Lock system.

The three holes in a taper lock bush serve two distinct functions:

• Installation holes (tapped): Two of the three holes are threaded. Screws tightened into these draw the bush axially into the hub taper, generating the clamping force that locks the assembly.
• Extraction hole (clearance, unthreaded): The third hole passes straight through the bush and lines up with a tapped hole in the hub face. When the same screws are transferred to this hole, tightening them bears against the hub face and jacks the bush back out of the taper — reversing the installation.

The two supplied screws are used for installation first, then transferred to the extraction position for removal. You never need more than two screws simultaneously — one hole is always empty.

For the 4030–5050 series (four-hole pattern), the same logic applies: three tapped installation holes, one clearance extraction hole, three screws supplied.

How to Remove a Taper Lock Bush

Correct removal takes less than five minutes when the bush has been properly installed and maintained. It takes considerably longer — and risks damage — when the bush has seized.

Standard removal sequence

1. Remove all installation screws completely and set aside.
2. Clean the threads of the extraction hole in the hub face with a pick or wire brush.
3. Transfer the screws to the extraction (clearance) holes — passing through the bush and engaging the threaded holes in the hub face behind it.
4. Tighten the extraction screws progressively and alternately. They bear against the hub face and drive the bush back out of the taper.
5. Once the taper releases, the bush and hub assembly will move freely on the shaft — slide off.

Removing a seized taper lock bush

Taper lock bushes seize due to: corrosion between the bush taper and hub bore (particularly on outdoor or wash-down equipment), fretting corrosion from micro-slip, or over-time metal-to-metal adhesion on un-lubricated assemblies. The extraction sequence above is still the correct first attempt — apply progressive torque before trying anything else.

1. Apply a penetrating oil (Inox MX3, WD-40 Specialist, or equivalent) liberally at the bush/hub interface — the gap at the split line is the best entry point. Allow 30–60 minutes to penetrate.
2. Attempt the standard extraction sequence again. If the screws are bottoming out without releasing the bush, use longer extraction screws (same diameter/thread pitch, longer grip length) to maintain progressive jack force.
3. Apply heat carefully to the hub — not the bush. Heating the hub causes it to expand fractionally, relaxing the grip on the bush taper. Use a heat gun rather than a torch; if using a torch, keep the flame moving and avoid sustained spot heating.
4. As the hub expands, apply progressive extraction torque simultaneously.
5. If the bush still will not release: use a drift punch in the split of the bush (the longitudinal slot) to expand the split slightly. This reduces the grip on the shaft and hub simultaneously and is usually enough to release the assembly.

After extraction, inspect the bush taper and hub bore. If the taper shows galling (surface tear marks), the bush should be replaced. If the hub bore shows deep scoring, the hub should be replaced — a new bush in a damaged hub will not seat correctly and will always be prone to slip.

Steel vs Cast Iron: Which Taper Lock Bush Material Should You Choose?

Most catalogued taper lock bushes — and most of the stock you will find at any Australian supplier — are cast iron (grey or ductile iron). Cast iron has the compressive strength needed to generate clamping force under the fixing screws, machines cleanly, and holds dimensional accuracy well. For the majority of industrial drive applications, cast iron is the correct choice.

Steel taper lock bushes exist for applications where cast iron's limitations become critical. Here is how to decide:

Property	Cast Iron	Steel
Cost	Lower	Higher (20–50% premium typical)
Tensile strength	Moderate (grey iron ~200 MPa)	High (mild/alloy steel 400–800+ MPa)
Impact resistance	Brittle — cracks under shock load	Ductile — deforms without fracture
Corrosion resistance	Rusts readily without protection	Also rusts — but can be surface treated
Galvanic risk (with SS shaft)	Higher (cast iron + SS = active pair)	Lower with anti-galling compound
Machinability (boring to size)	Excellent — machines cleanly	Good — slightly harder to machine
Seizure risk on removal	Can gall onto SS shafts	Lower with correct anti-seize
High-shock applications	Not recommended	Recommended
Food processing / washdown	Not recommended	Stainless steel variant available

When to specify steel

• Crusher, screen, and shaker drives: High shock loading will crack cast iron bushes over time. Steel or ductile iron is mandatory.
• Food processing and washdown environments: Cast iron corrodes rapidly in regular washdown. Stainless steel taper lock bushes (or stainless steel hubs with steel bushes) are used in dairy, meat processing, and beverage plant.
• Stainless steel shafts: Use a steel bush with anti-seize compound to minimise galling risk during both installation and removal.
• Marine and offshore environments: Cast iron corrodes in salt air. Steel with surface treatment (zinc plating, phosphate) is preferred.
• High-torque reversing drives: Where load direction reversal is frequent (hoists, reversing conveyors), the impact fatigue resistance of steel is a tangible advantage.

QD Bushing vs Taper Lock: Key Differences

Both systems mount power transmission components onto shafts using a tapered sleeve and fixing screws, but they are not interchangeable and are dominant in different markets. Understanding the difference prevents wrong-specification ordering — particularly when replacing components on older or imported equipment.

Feature	Taper Lock Bush	QD Bushing
Taper ratio	1:12 (4.76°)	1:6 (9.46°)
Standard	BS 4235 Part 2	AGMA / ANSI (US)
Market prevalence	Australia, Europe, UK	North America (dominant), some AU OEM
Hub design	Plain bore hub, bush inserts from face	Flanged hub, bush seats from flange side
Assembly method	Bush inserted, screws tighten into bush	Hub assembled around bush on shaft, screws clamp flange
Screw access	From drive face of hub	From flange face (outside of drive)
Removal	Screws transferred to extraction holes	Screws moved to jack-bolt holes in flange
Interchangeability	Any BS 4235 Pt 2 compliant supplier	Any AGMA-compliant supplier (QD series: SH, SK, SF, E, F, J, M, N, P, Q, S)
Ease of axial adjustment	Good — slide before torquing	Moderate — flange limits adjustment range

If you are replacing a component on a piece of American-origin plant (e.g. Dodge, Rexnord US, Martin Sprocket) and the hub has a flanged face with an external bolt circle, it is almost certainly a QD bushing installation. QD bushes are designated by letter codes (SH, SK, SF, E, F, J, M, N, P, Q, S) rather than four-digit numbers.

Taper lock bushes fit the Australian industrial market because BS 4235 Part 2 is the dominant standard for locally and European-sourced plant. Both systems work reliably — the choice is dictated by what the hub is designed for, not by performance preference.

Keyless Shaft Locking: Alternatives to Taper Lock Bushes

Taper lock bushes require a keyway in both the shaft and the bush bore. Cutting a keyway requires a broach or a keyway milling machine — not always available in the field — and the keyway itself is a stress concentration in the shaft. For applications where keyway machining is not practical or where you need to transmit high torque without a keyway, keyless shaft locking devices are the engineered alternative.

These devices — sold under names including Fenner B-LOC, Ringfeder RFN, Trantorque, and Tollok — work by clamping the hub directly to the shaft through radial friction force, generated by tightening a series of fasteners that compress a conical interface. They are entirely keyless: no keyway in the shaft, no keyway in the hub bore.

When keyless locking makes more sense than taper lock

• No keyway possible: Hollow shafts, worm gear shafts, and some motor shafts cannot accommodate a keyway without structural compromise.
• Field installation without a machine shop: A keyless locking device can be installed on a smooth shaft without special tooling — only a torque wrench is needed.
• Fine angular positioning: Cams, eccentric drives, and indexing mechanisms require precise angular setting. Keyless locking allows the hub to be positioned at any angle before clamping, with no key to align.
• High shock or reversing loads: Keyless clamping distributes load over a large contact area. Key drives concentrate load at the key edges and keyway root — fatigue failure starts here under high-cycle shock.
• Large shaft diameters: Above 150 mm shaft diameter, keyless locking is often more economical than a large taper lock bush assembly.

Taper Lock Bushes with Pulleys, Sprockets and Sheaves

Taper lock bushes are the standard mounting method for four of the most common power transmission components in Australian industry: V-belt pulleys, synchronous (timing belt) sprockets, roller chain sprockets, and V-groove sheaves, and flexible coupling hubs. Understanding how the bush interfaces with each component helps with selection and troubleshooting. Taper lock hubs are also used with jaw, HRC and cone ring couplings — see the Flexible Coupling Guide for hub configuration and coupling selection guidance.

V-belt pulleys

V-belt pulleys (also called V-belt sheaves) are the most common application for taper lock bushes in Australian industry. The pulley hub is machined to accept the standard BS 4235 Part 2 taper, and the bush series is stamped on the hub flange. Pulley groove alignment is critical for belt life — after fitting, check that the grooves of both pulleys are in line across the full drive face using a straight edge or laser alignment tool. A misaligned drive caused by an incorrectly positioned taper lock bush is a leading cause of premature V-belt failure.

Timing belt sprockets

Synchronous (timing belt) sprockets use taper lock bushes in the same way as V-belt pulleys, but angular accuracy is more critical — tooth profile alignment errors cause belt tracking failure and edge wear. When fitting a timing belt sprocket, confirm that the sprocket flange faces are running true (dial indicator check, ≤ 0.03 mm TIR is the typical tolerance for precision timing drives). See the Synchronous Timing Belt Guide for full drive design context.

Roller chain sprockets

Roller chain sprockets are routinely mounted on taper lock bushes, particularly for sprockets that need periodic repositioning or replacement. The installation procedure is identical to V-belt pulleys. The key alignment check for roller chain is axial — the sprocket centreline must be within the drive chain's maximum permissible misalignment (typically ≤ 1° angular and ≤ 3 mm parallel offset for standard ANSI chain). A sprocket that has been incorrectly positioned axially by an incorrectly seated taper lock bush causes chain edge contact and rapid wear. See the Industrial Roller Chain Guide for chain drive alignment requirements.

Flexible couplings

Many flexible shaft couplings — particularly jaw couplings, Fenaflex tyre couplings, and disc couplings — use taper lock bushes to mount the coupling halves onto the driver and driven shafts. The same BS 4235 Part 2 procedure applies, but coupling installation requires additional attention to shaft-to-shaft alignment after the bushes are fitted. For a full treatment of coupling types and alignment requirements, see the Shaft Couplings Guide.

Common Taper Lock Bush Problems and Solutions

Most taper lock bush problems in service trace back to one of four root causes: contamination at assembly, incorrect shaft tolerance, insufficient screw torque, or incorrect size selection. The table below maps symptoms to probable causes and remediation steps.

Symptom	Most Likely Cause	Remediation
Bush slips on shaft under load	Insufficient screw torque; contaminated taper surface; shaft undersize	Remove bush, clean taper, check shaft tolerance, reinstall and torque correctly. Re-torque after 24h run.
Excessive vibration after fitting	Bush not fully seated; hub running eccentric; bent shaft	Check runout with dial indicator. If hub is eccentric, remove and inspect taper bore for damage. Verify key is not oversized.
Bush will not release on removal	Corrosion or fretting at taper interface; over-torqued screws	Penetrating oil + soak, progressive extraction torque, heat on hub body. See removal section above.
Fixing screws pulling out of threads	Wrong screw length; stripped extraction hole; wrong screw grade	Use correct length screws (Grade 8.8 minimum). If extraction hole is stripped, thread-repair with Helicoil or Recoil insert.
Hub cracked after removal attempt	Hammer impact on cast iron hub; heat applied too aggressively	Replace hub. Do not use hammers on cast iron hubs. Replace with steel or ductile iron hub if shock is an ongoing issue.
Keyway fretting (rust-coloured powder at key interface)	Key loose in keyway; shaft/bush tolerances out of spec	Replace key with correct size. Inspect shaft keyway for wear. Apply Loctite 641 retaining compound to key on reassembly if keyway is marginally worn.
Belt tracking off-centre	Pulley incorrectly positioned axially; bush not fully seated	Re-fit with dial indicator check. Confirm taper fully seated before torquing. Check belt and sheave groove alignment.

Maintenance and Inspection Schedule

Taper lock bushes are low-maintenance components, but they benefit from scheduled inspection — particularly in environments with vibration, temperature cycling, or process washdown.

• Initial re-torque: After the first 24–48 hours of operation, re-torque all fixing screws to the specified value. This compensates for initial bedding-in relaxation.
• Quarterly inspection (or at each planned maintenance shutdown): Check fixing screw torque. Inspect the bush split and adjacent hub bore for fretting corrosion (reddish-brown powder residue). Check for lateral play in the hub by pushing the hub face sideways — any movement indicates the bush has loosened or the shaft has worn.
• Annual inspection or on disassembly: Remove the bush, clean and inspect the taper surfaces, check the key and keyway for wear, verify shaft tolerance has not changed due to wear. Re-apply light machine oil to the bush bore before refitting.
• Corrosion protection: On outdoor, coastal, or washdown equipment, apply a protective coating (zinc-rich spray, wax, or silicone grease) to exposed bush and hub surfaces between shutdowns. Do not apply grease to the taper bore interface.

Buying Taper Lock Bushes in Australia

Taper lock bushes are manufactured to BS 4235 Part 2, which means they are fully interchangeable between suppliers at the same series designation and bore size. You do not need to match manufacturer brands — an AIMS-supplied 2517 bush with 45 mm bore will seat correctly in a Fenner, Dodge, or Rexnord 2517 hub.

When ordering, you need to specify three things:

1. Series: e.g. 2517 — determines the hub compatibility and maximum bore range.
2. Bore diameter: The actual shaft diameter in millimetres (metric) or inches (imperial). The bush is bored to this dimension.
3. Keyway: Standard parallel keyway dimensions are machined as a default. Specify if you require no keyway, or a non-standard keyway dimension.

AIMS Industrial stocks taper lock bushes across the full 1008–5050 series in common metric bore sizes for same-day or next-day despatch from Sydney. Less common bore sizes and imperial bores are available on request with a short lead time.

Browse the AIMS Industrial taper lock bushes range →

For V-belt pulleys, timing sprockets, chain sprockets, and other taper-lock-mounted drive components, the AIMS power transmission range carries compatible hubs across the same series.

Frequently Asked Questions

What is a taper lock bush?

A taper lock bush is a split, tapered sleeve that locks a power transmission component — such as a pulley, sprocket, or sheave — onto a shaft. The 1:12 external taper engages the matching bore of the hub; tightening the fixing screws draws the bush inward, generating a high clamping force without requiring a press fit. The bush transmits torque via a parallel key seated in a matching keyway on both the bush and the shaft.

What do taper lock bush numbers mean — for example, 1610 or 2517?

The four-digit code identifies the size series. The first two digits indicate the nominal bore range (maximum bore approximately equal to the first two digits × 10 mm); the last two digits indicate the bush length in millimetres. A 1610 bush has a maximum bore of around 50 mm and is 42 mm long. A 2517 bush has a maximum bore of around 75 mm and is 44 mm long.

What shaft tolerance is required for a taper lock bush?

BS 4235 Part 2 specifies shaft tolerance h8 as the recommended fit for taper lock bushes. H8 gives a light interference to clearance fit that allows assembly by hand but prevents shaft movement after the bush is tightened. Shafts ground to h6 or h7 also work and give a slightly tighter pre-fit. Avoid k6 or m6 (interference) shafts — the bush cannot be inserted without damage.

Can you use a taper lock bush without a key?

Most taper lock bushes require a parallel key to transmit torque. However, keyless installation is permitted for very light or unidirectional loads if the manufacturer's datasheets confirm it, and the hub's keyway is left open. For truly keyless applications requiring higher torque, keyless shaft locking devices (such as Fenner B-LOC, Ringfeder, or Trantorque) are engineered alternatives to taper lock bushes.

Why does a taper lock bush have fewer screws than holes?

The holes serve two distinct purposes: installation holes (tapped) draw the bush into the hub when screws are tightened into them; extraction holes (clearance) drive the bush back out when screws are transferred and tightened against the hub face. For a three-hole pattern, two screws are supplied — they are used in the two tapped installation holes, then transferred to the clearance extraction holes for removal. One hole is always left empty at any given time.

How do you remove a taper lock bush that is seized?

First remove all installation screws and transfer them to the extraction (clearance) holes. Tighten the screws progressively and evenly — they bear against the hub face and jack the bush back out. If the bush will not move, apply penetrating oil at the interface, allow 30 minutes, then repeat. Do not hammer the hub face; do not use heat without removing any sealing compound first. Severely seized bushes on stainless shafts may require mechanical splitting with a cold chisel at the bush split, as a last resort.

What is the difference between a taper lock bush and a QD bushing?

A QD (Quick Detach) bushing uses a 1:6 taper — steeper than the 1:12 taper of a taper lock bush. QD hubs are flanged and split along the face, allowing the hub to be assembled around the bush before tightening. QD bushes are prevalent in North American OEM equipment; taper lock bushes are dominant in Australian, European, and UK industrial applications. The two systems are not interchangeable — they have different bolt circles, taper angles, and hub designs.

What torque should I use to tighten taper lock bush screws?

Tightening torque is specified by the bush series, not by screw size alone. As a general guide: 1008–1310 series use M6 screws at approximately 9–12 Nm; 1610–2012 series use M8 screws at approximately 25–30 Nm; 2517–3030 series use M10 or M12 screws at approximately 50–80 Nm; 4030–5050 series use M16 screws at approximately 180–200 Nm. Always refer to the manufacturer's datasheet for the specific series. Tighten in a cross pattern in three progressive passes.

Can taper lock bushes be reused?

Yes, taper lock bushes can be reused provided the taper bore is undamaged, the keyway shows no fretting or deformation, and the fixing screws retain full thread engagement. Clean both the bush taper and hub bore with solvent, inspect for pitting or galling, and lightly grease the taper before refitting. If a bush has been seized and required forced extraction, inspect the taper carefully — any scoring or raised metal must be dressed with a fine file before reuse.

What is the taper angle of a taper lock bush?

Taper lock bushes have a 1:12 taper (also expressed as 4.76° included angle or approximately 2.39° per side). This is a self-locking taper — when driven home, the clamping force maintains itself without fastener pre-load alone. By comparison, a QD bushing uses a 1:6 taper, and a Morse taper (used in machine tool spindles) uses 1:19.002. The 1:12 ratio is specified in BS 4235 Part 2.

What is the difference between cast iron and steel taper lock bushes?

Standard taper lock bushes are cast iron (grey or ductile), which provides adequate strength for most conveyor, fan, and pump drives. Steel taper lock bushes are used in high-shock, high-torque, or corrosive environments — including food processing, marine, and chemical plant — where cast iron's brittleness would risk failure. Steel bushes cost more but accept higher dynamic loads and are less prone to cracking on seizure. Steel bushes are also recommended when mounting on stainless steel shafts to reduce the risk of galling.

How do I know which taper lock bush fits my pulley or sprocket?

The hub of a taper lock pulley or sprocket is stamped or labelled with its bush series (e.g. '2517' or 'TL2517'). Cross-reference the required shaft bore against the size table for that series — for example, a 2517 bush can be bored from a minimum of 15 mm to a maximum of 55 mm. If the shaft bore exceeds the maximum for that series, the next larger series is required. AIMS Industrial holds stock across all major series — see the taper lock bushes collection for current bore availability.

Are taper lock bushes metric or imperial?

Taper lock bushes are made in both metric and imperial bore sizes. Australian industrial plant predominantly uses metric shafts, so metric bore stock is standard. Imperial bore bushes (in inch fractions) are available for older imported equipment — particularly US and UK-origin machinery. The bush series designation (e.g. 2517) is the same regardless of bore dimension — only the bored diameter differs. Most suppliers, including AIMS, carry standard metric bores and can source imperial bores on request.

What causes a taper lock bush to slip on the shaft?

Bush slip is caused by: insufficient screw torque (most common), incorrect shaft tolerance (shaft undersize allows the bush to seat before adequate clamping force is reached), contamination of the taper surface with oil or grease at assembly, a damaged or missing key, or a bushing that has been incorrectly matched to the hub (wrong series). Slipping generates heat and fretting — if caught early, re-torquing after cleaning and dressing the taper may recover the joint; if fretting is visible, replace the bush.

Can I fit a taper lock bush on a stainless steel shaft?

Yes, but use a steel taper lock bush rather than cast iron, and lubricate the shaft with an anti-galling compound (copper-based anti-seize or molybdenum disulphide paste) before fitting. Stainless-on-cast-iron contact risks galling and surface pick-up during installation and removal. Steel-on-stainless contact with anti-seize is far more manageable. Check the shaft tolerance is h8 or better — stainless shafts are sometimes supplied with wider tolerances than standard engineering steel.