Abstract: A steering control system includes a steering circuit, a primary control circuit and a redundant control circuit. The primary control circuit includes primary proportional control valves, and a primary pilot valve having a thermal bleed of pilot fluid to warm the primary pilot valve when not operating to control the steering circuit. The redundant control circuit includes secondary proportional control valves, and a pressure reducing valve having a thermal bleed orifice allowing fluid flow to warm the pressure reducing valve when not operating to control the steering circuit. The thermal bleeds may also flow past the proportional control valves to raise their temperatures. The circuits of the steering control system are contained in a single valve group housing.

Abstract: A steering control system includes a steering circuit, a primary control circuit and a redundant control circuit. The primary control circuit includes primary proportional control valves, and a primary pilot valve having a thermal bleed of pilot fluid to warm the primary pilot valve when not operating to control the steering circuit. The redundant control circuit includes secondary proportional control valves, and a pressure reducing valve having a thermal bleed orifice allowing fluid flow to warm the pressure reducing valve when not operating to control the steering circuit. The thermal bleeds may also flow past the proportional control valves to raise their temperatures. The circuits of the steering control system are contained in a single valve group housing.

Abstract: A hydraulic system having a source of pressurized fluid and a fluid actuator with a first chamber and a second chamber. The hydraulic system also has a first valve configured to selectively fluidly communicate the source with the first chamber and a second valve configured to selectively fluidly communicate the source with the second chamber. The hydraulic system also has a supply passageway and a signal passageway each disposed between the first and second valves in parallel. The hydraulic system also has a proportional pressure compensating valve configured to control a pressure of a fluid directed between the source and the first and second valves. The hydraulic system further has a fluid passageway disposed between the supply and signal passageways to fluidly communicate the supply and signal passageways.