valve with exhaust port, ensures quick return of cylinder therefore cycle time reduces Flow control valve The combination throttle valve connected to check valve is called one way flow control valve, while air passes from one direction to other the check valve will not allow the air flow (As the check valve allows flow only in one direction) while through the restricted way of throttle compressed air flow takes place. While the air comes out from other way both the ways of throttle as well as the check valve opens to pass the compressed air therefore the piston moment in one direction can be controlled. Time delay valve The combination of 3/2 direction control valve, reservoir and flow control valve is time delay valve. This valve is used to delay the actuation of cylinder after pressing the push button or pedal etc. Pressure relief valve The pressure relief valve is used to maintain the system set pressure, in case if the system set pressure increases the pressure relief valve gets opens and exhaust the compressed air to atmosphere See also Pneumatics ru:Пневмоавтоматика