A linear solenoid has a main housing (1) that is of a cylindrical shape and has an internal core element (2) and an external projection (3) that provides a guide for pin (4) acting as a bearing location for an armature (10). The armature is supported on linear ball bearing races (11). Coaxial with the armature is a pole plate (8) that is circular in cross section and fits in a housing recess (9) and has a bore that provides an air gap (L) with the armature. The accurate concentric location of the pole plate during assembly is provided by issuing an insert that fits over the pin while the plate is installed. The coil (5) fits in the annular space.
