Abstract: A power steering trim control system for use with steering mechanisms provided in automotive vehicles. The trim system includes a flow distribution valve (38) which selectively directs fluid pressure to segregated groups (34, 36) of valve lands (32) of a rotary valve (24) in proportion to the deflection of a torsion bar (22). The valve lands (32) are angularly off-set from those found in the prior art in order to produce a desired biasing, or torque compensation. The torque which is manually transmitted is progressively supplemented by fluid pressure delivered to the pressure movable part (14) of a steering linkage (16). The invention also includes a process control circuit (60) which is provided with a vehicle speed sensor (60) for generating an electrical signal representative of vehicle speed.