Abstract: A pilot stage of an electrohydraulic control valve controls the position of a pilot actuated main stage by controlling fluid flow through a flow path that connects a supply port to an exhaust port and to an end of the main stage. A proportional valve of the pilot stage has a valve element for establishing a variable flow control orifice to control fluid flow through the flow path and a bleed orifice disposed in the flow path downstream of the proportional valve to generate fluid pressure upstream of the bleed orifice and at the end of the main stage.

Abstract: A system that allows a driver of a towing vehicle to control self contained brakes of towed vehicle thorough application of towing vehicle brakes. When driver applies towing vehicle brakes and brake light switch is activated a solenoid in conjunction with compressor and air tank in towed vehicle releases air pressure to an air cylinder depressing towed vehicle's brake pedal. If the towed vehicle detaches from towing vehicle while traveling a second solenoid will be activated by a breakaway switch to bring the towed vehicle to a rapid stop.

Abstract: A compressor including a chamber having a standing acoustical wave therein, the wave having at least first and second velocity nodes, the first velocity node having a smaller cross-sectional area than the second velocity node, a high pressure inlet adapted to receive relatively high pressure gas, an inlet mechanism operably connected to the high pressure inlet and to the chamber, the inlet mechanism being associated with the first velocity node and adapted to supply pulses of the relatively high pressure gas to the chamber at a predetermined rate, at least one outlet valve associated with the second velocity node of the chamber and adapted to allow gas at a relatively low pressure to pass therethrough, and a low pressure inlet operably connected to the chamber.