Abstract: A solenoid includes a base formed with an external taper and an adjacent hub sleeve also formed with an external taper, the base and hub being joined by an alignment piece of non-magnetic material formed with a pair of internal tapers which are proportioned to mate with the external tapers of the hub and the base. The alignment insert assures and maintains a predetermined concentric coaxial alignment of the hub and base with respect to a common movable armature.

Abstract: A control device for an eddy current retarder having a plurality of energizing windings comprises an insulating support carrying a plurality of connecting terminals for connection to the retarder windings and a junction terminal for connection to one pole of a power supply. A plurality of contactors are provided for controlling the energizing of the retarder windings, each contactor corresponding to a connecting terminal and comprising first and second fixed contact members, a bridge contact co-operating with the first and second fixed contact members, and a pull-on contactor winding controlling the bridge contact. A first contact plate connects the first contact member of each contactor to the corresponding connecting terminal and a second common contact plate connects the second contact members of the contactors to the junction terminal. Each contactor winding is connected to a respective control terminal which is connected to a control selector for consecutively energizing the control terminals.