GEAR AS-SUN 6Y7270 - Caterpillar

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(39) Pilot oil filterOil flows from pilot and braking pump (32), through pilot oil filter (39) to brake accumulator charging valve (26).
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(26) Brake accumulator charging valve
(40) Check valveOil for the parking brake, service brake, and pilot systems is drawn from hydraulic tank (36) to pilot and braking pump (32). The oil then flows through pilot oil filter (39) to check valve (40). Pilot oil flows from check valve (40) to brake accumulator charging valve (26).Brake accumulator charging valve (26) has two functions. Brake accumulator charging valve (26) maintains the pressure in the brake accumulator at a constant range while the engine is running. Also brake accumulator charging valve (26) divides pump flow between the brake accumulator system and the pilot system.
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(37) Pilot relief valveOil flows from brake accumulator charging valve (26), to pilot relief valve (37). Pilot relief valve (37) maintains the pilot system at a constant pressure. Pilot relief valve (37) relieves excessive pilot system pressure through a line to the hydraulic tank (36).
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(28) Check valve
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(22) Selector and pressure control valvePilot oil flows through check valve (28) to selector and pressure control valve (22).While pilot and braking pump (32) is supplying pilot oil, selector, and pressure control valve (22) blocks alternate oil from entering the pilot oil system.If pilot oil from pilot and braking pump (32) is not present at selector and pressure control valve (22), alternate oil flows into the pilot oil system from the steering system and the main hydraulic system.When the engine is off, alternate oil flows through selector and pressure control valve (22) through implement and steering solenoid valve (12). Oil from implement and steering solenoid valve (12) flows to pilot control valve (25) to lower the bucket. High-pressure oil from the head end of lift cylinders (6) enters the pilot system through selector and pressure control valve (22). The selector and pressure control valve (22) reduces the oil pressure and allows lower pressure oil flow to pilot control valve (25) via implement and steering solenoid valve (12). When pilot control valve (25) is moved to the LOWER position, pilot oil flows to the lift spool in main control valve (1). The lift spool moves to the LOWER position allowing the bucket to be lowered.
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(12) Implement and steering solenoid valveOil from check valve (28) also flows to implement and steering solenoid valve (12).When the implement and steering solenoid valve (12) is energized, pilot oil flows through implement and steering solenoid valve (12) to pilot control valve (25).
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(25) Pilot control valve (under cover)
(43) Joystick control leverJoystick control lever (43) controls the movement of pilot control valve (25). The pilot oil is blocked at pilot control valve (25) when joystick control lever (43) is in the HOLD position. Moving joystick control lever (43) will send pilot oil through pilot control valve (25). Oil from pilot control valve (25) flows to main control valve (1) to move the tilt spool or the lift spool.
Illustration 15 g01138909The lift arm positioner valve