Power steering system

摘要

In a power steering system of this invention, a control valve is provided for supplying working fluid to a power cylinder by an amount proportional to a steering effort supplied to an input shaft and obstructing supply of working fluid to the power cylinder when a steering wheel is in a neutral position. A conversion mechanism which includes an operation rod (operating device) capable of operating the control valve is provided for converting the steering effort supplied to the input shaft to displacement of the operation rod. A directional control valve is provided which is disposed between the control valve and the power cylinder for switching supply of working fluid from one of cylinder chambers of the power cylinder to the other according to the direction of the steering effort on the input shaft while controlling discharge of working fluid from the cylinder chambers.