Servo steering device for a motor vehicle having double axle steering has supplementary pump in case of a defect in the main pump

摘要

A servo steering device for a motor vehicle having double axle steering comprises a main pump (MP) driven by the vehicle and a supplementary pump (SP) not so driven, a hydraulic control valve (12) and servo cylinders (22) for the wheels. The rear servo is disconnected from the control valve if the supplementary pump is connected. A servo steering device for a double axle steering motor vehicle comprises a main pump (MP) driven by the vehicle motor and a supplementary pump (SP) otherwise driven, a hydraulic control valve (12) connected (10) to the pumps and servo cylinders (22) for front and rear wheels (17,21). A switch (24) disconnects the rear servo from the control valve and connects the left and right chambers (22L,22R) of the rear servo if the supplementary pump is connected to the control valve. An Independent claim is also included for a device as above in which there is a return channel from the main pump to the tank if the supplementary pump is connected.