Abstract: In an auxiliary power steering system, a steering linkage actuated limit valve assembly is maintained depressurized in its inactive state by one-way check valves blocking flow from the pressurized chambers of the steering servomotor and by by-pass valves which control the connection of the differential pressure operated valve to the vented chambers of the servomotor.

Abstract: A construction for the valving and road resistance reaction chambers utilizing the lower end of the steering spindle supported at the lower end of the steering housing by only two thrust bearings and utilizing a minimum of seals. The construction accomplishes the purpose of reducing friction in the steering of vehicles, especially important for heavy, high speed vehicles. The construction further realizes the advantage of requiring a minimum of space and an assembly of simple parts particularly advantageous in trucks having a tilting driver cabin.