These mechanically operated valves have been designed with three different types of actuation: - plunger - lever/roller - unidirectional lever/roller In each case, return is triggered by a mechanical spring. 3/2-way monostable valves Series 3 are normally closed in the rest position when pressure is supplied in 1 and are normally open when pressure is supplied on connection 3, the user port 2 remaining unchanged. 5/2-way valves Series 3 can be supplied via the ports 3 and 5 with two different pressures if a cylinder has to be operated using a delivery pressure which is different from the return pressure.