Abstract: Mechanical assemblies, particularly bearing assemblies, incorporate local sensing means for producing an electrical signal directly indicative of the movement of one part relative to another. The sensing means employs a toothed wheel or disc or a moulded magnetic plastics component which is designed to move, for example, rotate, with the one part and a sensor which is located to the other part. The sensor senses the motion of the toothed or moulded component and can utilize galvanomagnetic means, such as a Hall effect device, or a magnetoresistor, or a Wiegand effect device, to produce the aforesaid signal directly or after further processing.