HARNESS AS-CONSOLE 4263766 - Caterpillar

When the operator moves the pilot valve to the RAISE position, pilot oil flows from the pilot line into port (12) . The pilot oil flows through passage (11) into chamber (9) . When the oil pressure overcomes the force of spring (20) , spool (16) moves to the left. Pump supply oil flows from passage (15) around the spool into feeder passage (13) .As the oil flows into the feeder passage, oil pressure increases. This increase in oil pressure causes the spool (4) to move upward. The oil flows through spool (4) to spool (16) . On the right side of the feeder passage, the spool blocks the flow of oil. On the left side of the feeder passage, the oil flows through the spool to passage (17) . As the oil flows into passage (17) , the oil pressure increases. When the oil pressure overcomes the force of the spring inside the pilot operated check valve (23) , the pilot operated check valve opens. The oil flows through the check valve into passage (25) . Then, the oil flows through port (1) to the head end of the lift cylinders.Some of the oil that flows through spool (4) flows around the spool into the spring chamber that is on top of the spool. The flow of oil into the spring chamber causes the oil pressure in the chamber to increase. The force of spring (3) and the oil pressure in the spring chamber will equal the oil pressure that is flowing to the tilt cylinders.The oil pressure in the spring chamber is sensed in the resolver. If this circuit is the only circuit that is active, or this circuit has a work port pressure that is higher than the other circuits that are active, the load sensing pressure flows into load sensing passage (2) until the oil pressure in the load sensing passage is equal to the oil pressure that flows to the work tool. This pressure flows to the pump actuator group in order to control the output from the pump.Oil from the rod end of the lift cylinder flows through port (5) and passage (6) . The oil flows around spool (16) to passage (14) . Then, the oil flows to the tank.When the operator releases the pilot valve, the pilot oil flows toward the pilot valve and to the tank. Pilot operated check valve (23) closes. Spring (20) moves spool (16) to the HOLD position. The oil in passage (8) drains through the hole and the passage inside spool (16) to passage (14) . The oil then drains to the tank. Pilot operated check valve (23) blocks the hydraulic oil in the hydraulic lines to the head end of the lift cylinder.LOWER Position
Illustration 3 g01415221
(1) Port (2) Load sensing passage (3) Spring (4) Spool (5) Port (6) Passage (7) Check valve (8) Passage (9) Chamber (10) Spring (11) Passage (12) Port (13) Feeder passage (14) Passage (15) Passage (16) Spool (17) Passage (18) Port