Power assisted steering mechanism

摘要

A power assisted steering mechanism comprises a power piston in engagement with sector and worm shafts, right and left cylinders selectively receiving the fluid under pressure to thereby assist the movement of the power piston, and a control valve means incorporated within the power piston to selectively transmit the fluid under pressure into said right and left cylinders. The control valve means comprises a slidable valve piston positioned so as to define a pair of primary reaction chambers and a pair of secondary reaction chambers, the primary reaction chambers being in fluid communication with the secondary reaction chambers through means of orifices, respectively, and the secondary reaction chambers being connected to each other through means of a variable orifice which reduces the fluid communication therebetween in response to a speed of the vehicle.