SEGMENT-RING 4V1391 - Caterpillar

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(1) Right side view of the main control valve (2) Line relief valve for rod end of auxiliary cylinders (3) Line relief valve for head end of auxiliary cylinders (5) Line relief valve for rod end of tilt cylinder (6) Line relief valve for head end of tilt cylinderIf machine is equipped with the optional auxiliary system, the auxiliary section of main control valve (1) will include line relief valves (2) and (3) .Line relief valves (2) and (3) protect the auxiliary cylinders from external shocks. When auxiliary cylinders pressure exceeds the setting of either line relief valve, the line relief valve vents the excess pressure to hydraulic tank (35) .The main control valve housing includes two line relief valves. One for rod end of tilt cylinder (5) and one for head end of tilt cylinder (6) .Line relief valves (5) and (6) protect the tilt cylinders from external shocks. When tilt cylinder pressure exceeds the setting of either line relief valve, the line relief valve vents the excess pressure to hydraulic tank (34).
Illustration 9 g02983239
(37) Check valve (38) Pilot oil pressure reducing valvePilot oil pressure reducing valve is located on the left side of the rear frame in the transmission compartment. Oil for the pilot circuit is supplied from hydraulic tank (35) to pilot and braking pump (22). The pilot oil flows through check valve (37) to pilot oil pressure reducing valve (38). Pilot oil pressure reducing valve (38) reduces the pilot and braking pump oil to the specified pilot pressure.
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View of the transmission compartment (31) Selector and pressure control valve The selector and pressure control valve (31) is located on the left side of the transmission compartment.The pilot oil, now at a reduced pressure flows through check valve (39) to selector and pressure control valve (31) .When brake and pilot pump supplies oil to pilot oil system, selector and pressure control valve (31) blocks alternate oil flow into pilot oil system.If brake and pilot pump fails, or oil is not available, the following will occur. Selector and pressure control valve (31) will allow alternate oil to flow into pilot oil system from steering system and main hydraulic system.Selector and pressure control valve (31) provides pilot oil to pilot control valve (27) to lower the bucket when the engine is off. High-pressure oil from the head end of lift cylinders (13) enters the pilot system through selector and pressure control valve (31). The selector and pressure control valve reduces the oil pressure and lets lower pressure oil flow through the implement and steering solenoid valve (40) to pilot control valve (27). When the pilot control valve 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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(40) Implement and steering solenoid valve (41) Parking brake control valveOil from check valve (39) flows to parking brake control valve (41). Oil flows to implement and steering