Abstract: A variable effort power steering system for an automobile includes a rotary valve power steering gear, a detent type variable effort detent system whereby a fluid detent pressure proportional to vehicle speed operates on a detent between an input member of the steering gear and an output member of the steering gear to prevent relative angular displacement therebetween until steering handwheel effort exceeds a threshold magnitude increasing with increasing detent pressure, and a shunt system between the two working chambers of the steering assist fluid motor. The shunt system includes a shunt valve in a shunt passage between the working chambers which is closed at zero or low vehicle speed and is progressively opened by detent pressure as vehicle speed increases whereby progressively more fluid is shunted from the active working chamber to the reservoir at higher vehicle speeds.

Abstract: A speed sensitive detent system for a variable effort power steering gear. A detent support portion on the output member of the steering gear has a plurality of internally threaded radial insert bores therein. A detent insert is threaded into each insert bore and includes a detent bore the centerline of which is offset from the centerline of the corresponding detent insert. A detent ball is received in each detent bore and biased by a servo fluid pressure into a detent groove in the input member of the steering gear angularly aligned with the insert bore. After the rotary valve of the steering gear is balanced during assembly of the gear, the detent inserts are rotated in their insert bores until the centerlines of the detent bores intersect the centers of the detent grooves so that the detent balls do not upset the hydraulic balance of the rotary valve when biased into the grooves by the servo fluid pressure.