Auxiliary power steering system for fitting to a stacker truck has a hydraulic steering actuator to engage one or more steerable wheels, a steering pump supplying hydraulic liquid and a hydraulic control unit to control its flow.

摘要

This system includes a hand-operated steering wheel (10). A hydraulic circuit (22) has a hydraulic steering actuator (16) to engage one or more steerable wheels (12), a steering pump (26) supplying hydraulic liquid and a hydraulic control unit (29) controlling the flow of hydraulic liquid to the actuator by relying on the turns of the steering wheel. An electric motor (24) connects to the steering pump to drive it. A sensor device (42) delivers a sensor signal containing information about the speed of the steering wheel's angle of rotation. A motor control unit (40) receives the sensor signal to control the electric motor by relying on the turns of the steering wheel. The motor control unit is designed to vary the electric motor's RPM.