Tapered Locking Bushes

What is a tapered locking bush?

A tapered locking bush, often called a taper lock bush, is a split, tapered sleeve used to fix pulleys, sprockets, gears, couplings, and other components securely onto a shaft. The outside of the bush is tapered to match a tapered bore in the component, and the inside has a parallel bore, usually with a keyway, that fits the shaft. When the bush’s screws are tightened, the bush is drawn into the tapered hub, closing down tightly onto the shaft and locking the component firmly in place.

Because the bush is split along its length, it grips the shaft evenly all the way around, centring the component accurately and holding it securely without the need for set screws digging into the shaft or a tight interference fit. One component with a tapered bore can also be fitted to many different shaft sizes simply by choosing a bush with a different bore.

A typical tapered locking bush has:

• Tapered outer surface - matches the tapered bore of the pulley, sprocket, or hub
• Parallel bore - fits the shaft, made in a wide range of metric and imperial sizes
• Keyway - usually cut into the bore so the bush can be keyed to the shaft for extra drive security
• Split - a slot along the length that lets the bush close down onto the shaft as it is tightened
• Screw holes - half-threaded holes shared between the bush and the hub, used for tightening the bush and, from the other side, for removing it

Key features:

• Secure shaft connection - locks components firmly onto the shaft to transmit high torque
• Self-centring - the taper centres the component accurately, reducing wobble and run-out
• Easy fitting and removal - fitted and removed with standard hand tools, without heating or pressing
• Flexible bore sizes - one tapered hub can fit many shaft sizes by changing the bush
• Reduced shaft damage - grips evenly around the shaft without marking it like set screws
• Standard sizes - made to common dimensions, so bushes and tapered components from different suppliers are usually interchangeable
• Durable construction - usually made from cast iron or steel with a protective finish

In simple terms, a tapered locking bush is a quick and reliable way to lock a pulley, sprocket, or hub onto a shaft, while keeping it accurately centred and easy to remove.

Why are tapered locking bushes essential?

Tapered locking bushes are essential because power transmission components must be fixed securely to their shafts to transmit torque without slipping, wobbling, or working loose. Traditional fixing methods, such as set screws, keyed interference fits, or welding, can damage shafts, be difficult to remove, or allow components to move over time. Tapered locking bushes solve these problems by giving a strong, evenly clamped, self-centring connection that is quick to fit and easy to remove.

Their main benefits are:

• High torque transmission - the clamping force and key transmit drive reliably
• Accurate alignment - the self-centring taper keeps pulleys and sprockets running true, reducing belt and chain wear
• Quick installation - fitted with a hex key or spanner, with no heating, pressing, or special tools
• Easy removal - the extraction holes allow the bush to be released quickly for maintenance
• Reduced stock - one tapered pulley or sprocket can suit different shaft sizes with a different bush, reducing the range of parts needed
• Shaft protection - even clamping avoids the damage caused by set screws and tight press fits
• Reduced downtime - components can be changed quickly during maintenance and repairs
• Cost-effective - a simple, economical way to mount components securely

Tapered locking bushes are used across a wide range of industries and applications, including:

• Belt drives - fixing V-belt and timing belt pulleys to motor and machine shafts
• Chain drives - fixing sprockets to drive and driven shafts
• Couplings - mounting flexible couplings to motor and gearbox shafts
• Conveyors - fixing pulleys, sprockets, and drums
• Fans and blowers - mounting fan hubs and pulleys
• Pumps and compressors - fixing drive pulleys and couplings
• Agricultural machinery - mounting pulleys and sprockets on drive shafts
• Manufacturing and processing - general power transmission across production equipment

The main types of tapered locking bushes

Tapered locking bushes are usually grouped by size, bore type, and the components they fit.

By size:

• Standard bush sizes - made in a range of sizes such as 1008, 1108, 1210, 1215, 1610, 1615, 2012, 2517, 2525, 3020, 3030, 3525, 3535, 4030, and larger. Each size suits a matching tapered bore and a range of shaft diameters
• Small bushes - such as 1008 and 1108, used on smaller pulleys and sprockets with lighter loads
• Medium bushes - such as 1210, 1610, and 2012, widely used in general industrial drives
• Large bushes - such as 2517, 3020, and above, used for larger shafts and heavier drives

By bore:

• Metric bores - in millimetre sizes, usually with a metric keyway
• Imperial bores - in inch sizes, usually with an imperial keyway
• Bores without keyways - for special applications where a keyway is not required

By material and finish:

• Cast iron bushes - the most common type, strong and economical
• Steel bushes - used where extra strength is required
• Stainless steel bushes - for food processing, washdown, and corrosive environments
• Phosphated or black finish - gives light corrosion protection for general use

Related components:

• Taper bore pulleys - V-belt and timing belt pulleys with tapered bores to suit taper lock bushes
• Taper bore sprockets - simplex, duplex, and triplex sprockets with tapered bores
• Weld-on hubs - hubs with a tapered bore that can be welded to fans, drums, or custom parts, allowing them to be mounted with a taper lock bush
• Bolt-on hubs - hubs that bolt onto components to give a tapered bore mounting
• Taper bore couplings - flexible couplings designed to fit taper lock bushes

How to choose the right tapered locking bush?

Choosing the right tapered locking bush means matching it to both the component and the shaft. Work through these points in order:

• Bush size - match the bush size to the tapered bore of the pulley, sprocket, coupling, or hub. The bush size is usually marked on the component, such as 1610 or 2012
• Shaft diameter - choose a bush with a bore that matches the shaft diameter exactly, such as 20 mm or 1 inch
• Metric or imperial - check whether the shaft is metric or imperial, and choose a matching bore and keyway
• Keyway - check that the keyway size suits the key and shaft
• Bore range - make sure the shaft size is within the bore range available for that bush size, as each size has a minimum and maximum bore
• Torque and load - choose a bush size suitable for the torque and load being transmitted
• Material - choose cast iron for general use, steel for higher strength, or stainless steel for corrosive or washdown environments
• Fixing direction - consider whether the bush will be fitted and tightened from the hub side or the bush side, especially when using weld-on or bolt-on hubs
• Matching components - if you are choosing new pulleys or sprockets, make sure their tapered bore suits the bush size you need
• Quality and brand - choose bushes from reputable suppliers for accurate tapers, bores, and keyways

FAQ - All you need to know about tapered locking bushes

What does a tapered locking bush do?

It fixes a pulley, sprocket, coupling, or hub securely onto a shaft. As the screws are tightened, the bush is drawn into the tapered hub and clamps tightly onto the shaft, holding the component firmly and centring it accurately.

What do the numbers in a taper lock bush reference mean?

The four-digit number is the bush size, such as 1008 or 1610, which must match the tapered bore of the component. The number after the dash shows the bore size. For example, 1008-20 is a 1008 bush with a 20 mm bore.

How do I know which bush size I need?

Check the bush size marked on the pulley, sprocket, or hub, or measure the tapered bore and compare it with a size chart. Then choose a bush with the bore that matches your shaft.

Can one pulley fit different shaft sizes?

Yes. A taper bore pulley can be fitted to different shaft sizes by choosing a bush of the same size with a different bore, as long as the shaft is within the bore range for that bush size.

How do I fit a tapered locking bush?

Clean the bush, shaft, and tapered bore, and remove any oil or grease from the taper. Place the bush into the hub, line up the half holes, and insert the screws loosely. Fit the assembly onto the shaft with the key, position it, then tighten the screws evenly and alternately to the recommended torque.

Should I lubricate the taper?

No. The tapered surfaces should be clean and dry for the bush to grip correctly. Lightly oiling the screw threads only can help with tightening, but follow the manufacturer’s instructions.

How do I remove a tapered locking bush?

Remove the tightening screws, then insert one or more of them into the removal holes, which are threaded in the bush side. Tightening the screws in the removal holes pushes the bush out of the taper, releasing the component.

Why is my pulley wobbling on the shaft?

Common causes include uneven tightening of the screws, dirt or damage on the taper, a worn shaft or keyway, or a bush that does not match the shaft size. Remove, clean, and refit the bush, tightening the screws evenly.

Are taper lock bushes from different brands interchangeable?

Standard taper lock bushes are generally made to common dimensions, so they are usually interchangeable between brands of the same size. Always check the size and bore before ordering.

What is the difference between a taper lock bush and a keyless locking element?

A taper lock bush uses a tapered hub and usually a key to transmit drive. A keyless locking element uses tapered rings to clamp onto the shaft and hub without a key, giving a backlash-free connection that can be positioned anywhere on the shaft.