Abstract: Wear of a rubbing member of a triction couple, such as an iron brake disc (15), which is subject to slow wear by frictional engagement by brake pads (17), is determined by attaching a carrier member (25) of wear determining arrangement (24) to the rubbing surface of the disc by electromagnet (28) and causing a transducer (33), such as magnetic displacement sensor having probe (33/2), to s an across the surface along a track (48). After an initial scan to map the surface the carrier is removed and re-attached after a period of brake usage, whereupon the surface is scanned again and wear assessed. The carrier is provided with feet (26/1) and biassed by a resilient electromagnet mount against the surface.

Abstract: A magnetic clamping arrangement (10) for holding the arrangement, and in particular a body (5), operably clamped with respect to a ferromagnetic surface (6) by way of a body datum face (8), comprises housing (12) mounted on the body, and electromagnet (16) carried by the housing. The electromagnet comprises a core (18), having three limbs 20.1, 20.2 and 20.3, each terminating in a pole face 22.1, 22.2 and 22.3, being formed by a plurality of ferromagnetic transformer laminations (26). stacked together and slideable with respect to each other in a direction to and from the pole faces. Lamination bias (36), in the form of masses 38, 40.1 and 40.2 of resilient compressible material, defined quiescent pole faces from which individual laminations may depart by sliding when forced against a surface having ridges and/or grooves extending in the lamination planes, but exerts a restoring force on such laminations so displaced.

Abstract: Wear of a rubbing member of a triction couple, such as an iron brake disc (15), which is subject to slow wear by frictional engagement by brake pads (17), is determined by attaching a carrier member (25) of wear determining arrangement (24) to the rubbing surface of the disc by electromagnet (28) and causing a transducer (33), such as magnetic displacement sensor having probe (33/2), to s an across the surface along a track (48). After an initial scan to map the surface the carrier is removed and re-attached after a period of brake usage, whereupon the surface is scanned again and wear assessed. The carrier is provided with feet (26/1) and biassed by a resilient electromagnet mount against the surface.

Abstract: A magnetic clamping arrangement (10) for holding the arrangement, and in particular a body (5), operably clamped with respect to a ferromagnetic surface (6) by way of a body datum face (8), comprises housing means (12) mounted on the body, and electromagnet (16) carried by the housing means. The electromagnet comprises a core (18), having three limbs 20.1, 20.2 and 20.3, each terminating in a pole face 22.1, 22.2 and 22.3, being formed by a plurality of ferromagnetic transformer laminations (26). stacked together and slideable with respect to each other in a direction to and from the pole faces. Lamination bias means (36), in the form of masses 38, 40.1 and 40.2 of resilient compressible material, delined quiescent pole faces from which individual laminations may depart by sliding when forced against a surface having ridges and/or grooves extending in the lamination planes, but exerts a restoring force on such laminations so displaced.