COMPONENT OPERATION / Pilot Valve During Metering or Decompressing (Output Curve: C to D) 1. When the control lever is further tilted in order to move pusher (2) downward more, hole (7) on spool (6) is opened to port P and pressure oil in port P flows into the output port. 2. Pressure in the output port acts on the bottom surface of spool (6) so that spool (6) is pushed upward. 3. Until upward force acting on the bottom surface of spool (6) overcomes the balance spring (4) force, balance spring (4) is not compressed so that spool (6) is not raised and pressure in the output port increases. 4. As pressure in the output port increases, the force to push spool (6) upward increases.
When this force overcomes the balance spring (4) force, balance spring (4) is compressed so that spool (6) is moved upward. 5. As spool (6) is moved upward, hole (7) is closed so that pressure oil from port P stops flowing into the output port and pressure in the output port stops increasing. 6. As spool (6) is moved downward and balance spring (4) is compressed, pressure acting on the bottom surface of spool (6) increases until pres- sure balances with the increasing spring force. This increasing pressure becomes pressure at the output port. F E D Pilot Pressure C B A Lever Stroke T523-02-05-001 T3-4-6