Abstract: A power steering device includes: a guide rod (1); a piston (3); a cylinder (2); a transmission mechanism (8, 9, 10) fixed to the cylinder (2), which transmits a steering force by moving integrally with the cylinder (2); a rack shaft (16) provided substantially parallel to the cylinder (2), which moves integrally with the cylinder (2); a pinion (18) provided on an input shaft (23) connected to a steering wheel, the pinion (18) engaging with a rack (25) of the rack shaft (16); and a valve mechanism (24) which causes one of the pressure chambers (4, 5) to communicate with a pressure source and another of the pressure chambers (4, 5) to communicate with a tank in accordance with a rotational load of the pinion (18) in relation to the rack (25).

Abstract: A rack-and-pinion mechanism (21) for changing a direction of wheels in accordance with a steering input, and a power cylinder (20) providing for power assist for operation of the rack-and-pinion mechanism (21) are provided. A rack shaft (9) of the rack-and-pinion mechanism (21) and a piston rod (3) of the power cylinder (20) are placed parallel to each other. The both ends of the rack shaft (9) and the both ends of the piston rod (3) are respectively linked through connecting members (6, 7). The piston rod (3) and the rack shaft (9) are separated from each other, thereby increasing the design flexibility of them.