The time-honoured method of linking up power transmission equipment via keys and keyways has its downsides, not least being the installation time and the problem corrosion can cause when attempting to dismantle an assembly. Friction bushes overcome the removal problem, but are generally not suitable for high-torque applications. New generation Taper-Grip keyless bushings from Fenner, however, address both of these issues and are claimed to transmit 300% more torque than traditional alternatives, such as friction-based locking bush designs.Fenner developed Taper-Grip for mounting its high-torque (38,000N), shaft mounted gearboxes in heavy-duty applications. The system uses a taper mechanism but unlike Fenner's Taper-Lock bush, it is presented in the form of a spiral or thread where the inner bushing engages with an outer sleeve (the hub) and exerts a clamping force when axial pressure is applied against the spiral taper (see diagram). The angle of the taper allows one face to ride up on the opposing face to squeeze the inner sleeve along its complete length. This provides a uniform and substantial clamping pressure along the entire length of the assembled bushing.The inner sleeve is slotted to allow for the radial compression, and when released the metal springs back away from the shaft. 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 (finger tight) 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 the unit, the cap head screws are finally tightened to the recommended setting using a torque wrench.When the bush screws are loosened and the tapers released, there is sufficient clearance within the assembly to allow easy removal. As the bush is screwed into the hub, it is inherently safe; even if the locking screws are completely removed, it cannot fall out during handling. You can find out more about Taper-Grip and its applications from Wyko Industrial Services.