Power steering device

Abstract

A power steering device for automobile type vehicles having a hydraulic power cylinder for assisting in steering front end wheels of the vehicle. The hydraulic power cylinder has a piston and piston rod fixed thereto reciprocable in two opposite directions of travel. The opposite ends of the piston rod are linked to respective front wheels of the vehicle for turning the individual steering wheels in a direction in which the piston rod travels. The piston rod has a rack with which a pinion is engaged and rotated by a shaft rotated by a drum coupled to the shaft for effecting manual steering. Another drum is provided and is rotated by the steering wheel by the vehicle driver. The drums are operationally coupled by a pair of flexible cables for rotating the drums by the steering wheel to move the piston rod rack in the desired steering direction. A direction control valve having a rotatable rotor is coupled to the drum which drives the rack pinion. The control valve rotor controls supply of pressurized hydraulic fluid from a pressurized source alternately on opposite sides of the piston for assisting driving the piston rod axially in the desired direction of travel for steering the vehicle and simultaneously controls the discharge of fluid from the power cylinder through ports on the hydraulic power cylinder in communication with ports on the direction control valve under control of the rotatable rotor and in dependence upon the direction of rotation of the control valve rotor from the steering wheel and the operatively associated two drums.