A hub (10) is fitted axially onto the knurled end (30) of a shaft and is held on the shaft by a spring washer (22) whose outer edge is shaped to press onto the hub and with an inner edge which grips one of a number of grooves (28) cut into the end of the shaft. No other fasteners are required. The hub, which can be part of a pinion, lies between the raised shoulder (36) of the shaft housing and the pressure edge of the spring washer. The knurled fitting has a set amount of friction axially to further secure the fitting.
