BOLT 3368237 - Caterpillar

Illustration 1 g01176526
Schematic of the Pilot Hydraulic System (1) Pilot oil filter. (2) Pilot pressure relief valve. (3) Hydraulic cooling fan (if equipped). (4) Fan control solenoid valve. (5) Travel speed solenoid valve. (6) Swing parking brake solenoid. (7) Swing motor. (8) Pilot on/off solenoid valve. (9) Pilot manifold. (10) Selector and pressure control valve. (11) control valve. (12) Pilot oil pump. (13) Travel control valve. (14) Travel motors. (15) Hydraulic tank.
Illustration 2 g01070478
Location of the pilot manifold on the machine
Illustration 3 g01072424
Pilot Manifold (4) Fan solenoid. (5) Travel speed solenoid. (6) Swing parking brake solenoid. (8) Pilot supply.The pilot hydraulic system contains the following components: pilot oil pump (12), pilot oil filter (1), pilot pressure relief valve (2), pilot manifold (9), optional hydraulic cooling fan (3), fan solenoid (4), travel speed solenoid valve (5), swing parking brake solenoid (6) and pilot on/off solenoid valve (8) .The pilot hydraulic system receives oil flow from pilot oil pump (12). The pilot oil pump is mechanically connected to the main pump.Reference: For more information about the pilot oil pump, refer to Systems Operation/Testing and Adjusting, "Gear Pump (Pilot)".The pilot oil pump draws oil from the case of the main pump. The pilot oil flows through pilot oil filter (1) to pilot manifold (9). The pilot oil filter has a bypass valve and a pressure relief valve (2) in the filter base.The pilot hydraulic system controls the following functions.
The pilot hydraulic system supplies pilot oil to selector and pressure control valve (10) .The selector and pressure control valve regulates the lowering of the boom, when the engine is stopped.When the engine is operating, pilot oil pump (12) sends pilot oil through pilot oil filter (1) to selector and pressure control valve (10) and pilot manifold (9). The pilot oil shifts selector and pressure control valve (10) to the CLOSED position.When the engine is stopped, the pilot oil flow is stopped. The selector and pressure control valve shifts allowing pressurized oil from the boom up circuit to flow through the pilot manifold to the solenoid valves on the boom control valve.When the joystick control is moved to the BOOM DOWN position, the pressurized oil flows through the solenoid valve to the spool in the control valve. The spool shifts allowing the boom to be lowered.Note: The engine start key must be in the ON position and the hydraulic lockout must be in the UNLOCKED position.
Illustration 4 g00995476
Hydraulic Lockout (Pilot Oil) on early machines (16) LOCKED position. (17) UNLOCKED position.
Illustration 5 g01176527
Hydraulic Lockout (Pilot Oil) on later machines (16) LOCKED position (17) UNLOCKED positionNote: When the hydraulic lockout is in the LOCKED position (16), no functions will operate.
The pilot hydraulic system supplies pilot oil to optional hydraulic cooling fan (3) .Pilot oil flows from pilot manifold (9) to fan control solenoid valve (4). Hydraulic cooling fan (3) operates at pilot system pressure. Fan control solenoid valve (4) is activated when the coolant temperature sensor, the hydraulic oil temperature sensor and/or the temperature sensor for the engine inlet