Description
Unrestricted upstream flow (A – A1) to the cylinder is possible through the check valve (3), while downstream flow (A1 – A ,or A1 – B) is locked by the leak free main spool (1) which is held closed by the spring and by the load induced pressure. With pilot pressure at X (joystick), the spool (1) is first vented to tank then it is remotely controlled and it slides to provide fine metering for the downstream flow; after the initial venting, the pilot pressure required to move the spool is load independent. The return flow (A1 – A) is slightly pressurized by the check valve (4) and is available to re-fill the opposite end of the cylinder through the check valve (5) and port (B), in order to prevent cavitation. The valve includes a small relief cartridge (2) which senses the A1 pressure (load induced) and opens under overload or shock conditions in order to pilot fully open the main spool (1): this allows any excess of pressure at A1 to be relieved downstream through A. For better safety and compact assembly, the A1 port is flanged (gasket mounted) directly on the actuator.
Note: for applications outside these parameters, please consult us.
