Abstract: A linear variable inductance transducer of the kind in which a spring-loaded plunger containing a magnetic core is axially movable in a stationary housing containing a coil assembly has the external surface of the plunger made of ceramic material, guided linearly solely by sliding in a ceramic bearing sleeve in the housing. The bearing sleeve may itself be flanged to form a bobbin for the coil assembly.

Abstract: A bore gauge incorporates one or more electromagnetic transducers housed in a shroud which in use is inserted into the bore to be gauged. Each transducer comprises a coil and a core movable within the coil. In one embodiment the coil and the core of a single transducer are mounted on opposite limbs of a flexible fork-like structure, the two limbs carrying gauging contacts for engagement with the walls of the bore. In other embodiments, incorporating a plurality of transducers, coils are rigidly mounted within the shroud and cores are mounted on flexible limbs set in slots in the surface of the shroud.