Pressure control valve for pneumatic working member - has diaphragm separating control and reference pressure chambers with several spring biased adjusters to vary the operating point

The pressure control valve has a housing with a reference pressure chamber (5) and a control pressure chamber (6) that are separated by a flexible diaphragm (3). The control pressure chamber has an external connection (7). A supply is connected via a central tube that has an end seat (9) against a seal (15) that locates in a carrier (10). A second path connects the lower chamber to the reference chamber via openings (13) in the diaphragm centre element. A pressure setting element (18) can be moved against a spring (19) to increase the load against the valve to increase the pressure. If the element is moved in the opposite direction the load is reduced and the pressure lowered. ADVANTAGE - Provides reduced leakage flow condition.