Abstract: A suspension system effects attitude control of a vehicle by supplying and discharging a pressure fluid to and from a suspension unit disposed between the body of the vehicle and a wheel. The suspension system employs a variable displacement pump to constitute a pressure source for supplying a pressure fluid to the suspension unit and controls the pump by a control mechanism such that the discharge of the pump is maintained at a substantially constant level, thereby enabling the load applied to the engine of the vehicle to be maintained at a substantially constant level, and thus achievinhg an increase in output of the engine.

Abstract: A compressor comprises a main compressor body of compressing air, an unloader valve device provided at the suction side of the main compressor body, a bleeding pipe provided between the ejection side of the main compressor body and the unloader valve device, and a controlling valve mechanism provided inside the bleeding pipe. The controlling valve mechanism opens by detecting the fluid pressure at the ejection side of the main compressor body. Further, the unloader valve device has a check valve which opens upon-no-load operation and stopping of the operation of the main compressor body, a main valve which opens due to the air released through the bleeding pipe when the controlling valve mechanism opens, a bleeding passage for releasing the released air supplied to the suction side of the check valve, and a relief passage which communicates when the main valve opens, to release the released air to the suction side of the main compressor body.