The master of suspense

US based Applied Motion Technologies has built on technology developed by British Inventor Philip Denne to design an electromagnetic linear actuator which is claimed to revolutionise vehicle suspension design.

Originally designed to replace hydraulics in entertainment simulators, alternative applications were soon realised for technology which is capable of positioning to within a few microns, speeds of up to 100 metres/second and thrusts of more than 100 tonnes.

AMT’s ServoRam is an electric motor that looks like a hydraulic ram, with a magnetic armature that moves freely along the axis of the motor. Fitted with bearing rings and a sliding seal to the outer tube, the armature also acts as a pneumatic piston. The design enables powerful and rapidly changing electromagnetic forces to be superimposed upon quasi-static or gas spring forces.

AMT claims that this single moving part can act as both a spring, damper and active component in the design of a suspension system.

The component is designed to double as a gas spring that automatically adjusts to road conditions and vehicle load distribution. Also, when driven in reverse it turns motion energy into electricity. In fully-active mode it draws power from the vehicle to control the vertical forces at each wheel point, and in semi-passive mode it takes power from the vertical motions of the wheels to control the attitude and position of the vehicle, returning surplus energy to a central source.

A spokesperson for AMT was reluctant to discuss specific car manufacturers, saying only that `development in Detroit is proceeding rapidly under confidentiality protection at this time.’