CHAMBER A. 5S1832 - Caterpillar

For example, when the bucket control valve is in the NEUTRAL position, passages (11), (12), (14) and (15) are closed. Pump oil in passages (6) and (17) does not flow to the bucket cylinder.When the main control valves are in the NEUTRAL position, the machine electronic control module sends an electrical signal input to the solenoid valve for the neutral flow control valve. When the neutral flow control valve is energized, the neutral flow control valve is open and most of the pump oil flows through the neutral flow control valve to the hydraulic tank. Neutral flow control valve (19) is open only when the main control valves are in the NEUTRAL position.When a control lever (joystick) and/or a travel levers/pedal is operated, an electrical signal input is received by the machine electronic control module. The machine electronic control module de-energizes the solenoid valve for the neutral flow control valve. The neutral flow control valve closes. Pump oil is blocked at the neutral flow control valve and flows to the stems in the main control valve body.When the control levers (joysticks) and/or the travel levers/pedals are returned to the NEUTRAL position, the main control valves return to the NEUTRAL position. The machine electronic control module energizes the solenoid valve for the neutral flow control valve. The neutral flow control valve opens. Most of the oil from the front pump flows through passage (17), passage (6), neutral flow control valve (19) and return port (13). The oil then flows to the hydraulic tank. Most of the rear pump oil flows through passage (6), neutral flow control valve (19) and return port (13). The oil then flows to the hydraulic tank.When the main control valves are in the NEUTRAL position, the machine is under a no-load condition. The main pumps provide a small amount of oil delivery to passages (6) and (17). Since neutral flow control valve (19) is open, the pump oil passes through the neutral flow control valve. The delivery pressure of this oil is maintained at 1960 kPa (285 psi) by the load sensing differential pressure relief valves.Individual Valve Operation
Illustration 6 g00636977
Circuit diagram for individual control valve operation (BUCKET CLOSE) (1) Bucket cylinder (2) Passage (true load signal pressure) (3) Signal duplication valve (4) Shuttle valve (5) Shuttle valve (6) Passage (pump flow) (7) Shuttle valve (8) Signal bypass valve (9) Passage (pump flow to flow compensator valve) (10) Passage (pump flow to spool) (11) Passage (duplicate load signal pressure) (12) Flow compensator valve (13) Passage (load sensing signal pressure) (14) Passage (true load signal pressure) (15) Passage (pump flow from flow compensator valve) (16) Bucket control valve (17) Passage (pump flow to control valve) (18) Shuttle valve (19) Passage (load sensing signal pressure to pumps) (20) Passage (return pilot oil) (21) Passage (pump flow to bucket cylinder) (22) Proportional valve for bucket cylinder head end (23) Pilot manifold (24) Pilot pump (25) Front pump (26) Rear pump (27) Passage (28) Passage (29) Spool (30) Spring chamber (31)