Abstract: An electrically powered drive mechanism for providing powered assistance to a vehicle steering mechanism. The drive mechanism includes a clutch responsive to drivingly isolate the motor from an output shaft coupling when torque in excess of a selected level is transmitted through the clutch.

Abstract: A fluid control system (10) for a vehicle power steering mechanism having a manually driven steering member and a fluid driven driving member (16) operatively connected to steering means of the vehicle by which steerage of the vehicle is achieved, the control system (10) including a first valve (12) for metering pressurised fluid flow to the fluid operated driving member (16) in response to the force required to move the steering means when operating the manually driven steering member, the first valve (12) including at least two independent metering valve means (170, 171) each of which are simultaneously operated by the steering member to meter fluid flow to and/or from the fluid operated driving member (16) at a predefined rate, at least one of the metering valve means (170, 171) communicating independently to a drain via a second valve (14), the second valve (14) being arranged to selectively connect and disconnect said at least one of said valve means (170, 171) to the drain in response to vehicle speed.

Abstract: A single-ended power assisted rack and pinion steering gear comprising a housing defining a cylinder, double-acting piston means reciprocable within said cylinder, said piston means including a piston rod one end of which is connectable to a wheel lever of a steerable road wheel of a vehicle to impart steering thereto, a pinion connectable to the steering control of a vehicle, a toothed rack one end of which is pivotally connected to the other end of the piston rod and the other end of which is free, means resiliently urging the toothed rack into meshing engagement with the pinion, and valve means associated with the pinion for directing fluid under pressure to one side or the other of the double acting piston means.