Couplings transmit more torque

Using a traditional keyed fitting to mount pulleys and shaft mounted gearboxes is commonly accepted as a crude method of securing power transmission equipment. But it is time consuming to install and allows fretting corrosion that often leads to difficulties should the unit need to be removed for service or replacement. Using a simple friction bushing type system can alleviate the problem of removal, but does not usually allow for high torque operation.

The new generation of Fenner Taper-Grip addresses both issues; it is engineered to transmit 300% more torque than traditional alternatives and still allow for simple fitting and removal in virtually any condition.

Designed primarily for mounting high power (torque levels up to 38000Nm) Fenner SMSR shaft mounted gearboxes in applications such as conveyors and quarrying equipment, the new Taper-Grip system uses a taper mechanism similar to the Taper-Lock bush.

However, it is in the form of a spiral or thread where an inner bushing engages with the outer sleeve (the hub section) and exerts a clamping force when axial pressure is applied against the spiral taper.

The angle of the taper is finely engineered to allow one face to ride-up on the opposing face and squeeze the inner sleeve along its complete length.

This results in a uniform and very high clamping pressure along the entire length of the assembled bushing, and a very easy removal process - just a tap in the opposite direction.

The inner sleeve is slotted to allow for the radial compression and when released the metal springs back away from the shaft.

Slots also allow for a wide shaft tolerance (tolerances of up to h11 can be accommodated).

Axial pressure exerted against the thread is applied using cap head screws mounted in a collar at one end of the bushing.

The inner bushing is screwed into the hub (only finger pressure required) while the assembly is positioned and locking force then applied by tightening the screws against a hardened collar.

In order to apply the huge clamping force available from Taper-Grip, the cap head screws are finally tightened to the recommended setting using a torque wrench.

In-house testing results showed a 300% increase in the amount of torque that could be transmitted when compared with earlier friction based locking bush designs.

The results complement the introduction of the new range of Fenner SMSR Power Plus shaft mounted gearboxes that actually transmit 50% more torque (up to 280kW) than competitive designs for the same design envelope.

The increased power required a locking system that could ensure the new higher power levels could be delivered to the driven shaft and yet maintains the ease and practicality of a tapered bushing design.

The Taper-Grip system can offer significant advantages when removing a gearbox.

There is a tendency for shaft mounted reducers in some environments to suffer from atmospheric or fretting corrosion and seizing solidly onto the shaft.

This can make removal difficult and time-consuming.

The Taper-Grip system eliminates this problem as the bush is manufactured from high-grade steel to enable high screw tightening torques that, in turn, generate a huge radial force to increase the grip on the driven shaft.

When the bush screws are loosened and the tapers released, there is sufficient clearance within the assembly to permit easy removal.

Because the bush is screwed into the hub, it is inherently safe.

Even if the locking screws are completely removed, it cannot inadvertently fall out during handling.