COMPONENT OPERATION / Pilot Valve OPERATION Front Attachment / Swing and Travel Pilot Valves Spool (6) head comes in contact with the upper sur- face of spring guide (3), which is kept raised by return spring (5). Neutral (Output Curve: A to B): 1. When in neutral, spool (6) totally blocks pressure oil from port P (the pilot pump). The output port is opened to port T (hydraulic oil tank) through the inner passage in spool (6). 2. Therefore, pressure in the output port is equal to that in port T. 3. When the control lever is slightly tilted, cam (1) is tilted and pusher (2) is downward. Pusher (2) compress return spring (5) along with spring guide (3) together. 4.
At this time, as pressure in the output port is equal to that in port T, spool (6) moves downward while keeping the lower surface of spool (6) head in contact with spring guide (3). 5. This status continues until hole (7) on spool (6) is opened to port P. F E D Pilot Pressure C B A Lever Stroke T523-02-05-001 T3-4-4