SEAL-U-CUP 1672354 - Caterpillar

Main control valve (14) directs the oil from implement pump (41) to the lift and tilt cylinders.Included in the main control valve housing are, line relief valve for rod end of tilt cylinder (5), line relief valve for head end of tilt cylinder (6) and main relief valve (17) .Line relief valves (5) and (6) protect the tilt cylinders from external shocks. When the pressure in the tilt cylinder exceeds the setting of either line relief valve, the line relief valve opens to vent the excess pressure to hydraulic tank (44) .When the pressure from implement pump (41) exceeds the setting of main relief valve (17), the relief valve opens to vent the excess pressure to hydraulic tank (44).
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(15) Lift circuit relief valveLift circuit relief valve (15) protects the main control valve, ride control accumulator and ride control components from high pressure spikes.
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(29) Check valve (39) Pilot and braking pump (40) Steering pumpThe pilot system has a two section gear type pump, mounted on the torque converter updrive housing. The two pump sections are: pilot and braking pump (39) and steering pump (40). The pumps use the hydraulic tank as a common reservoir.
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(35) Pilot oil pressure reducing valve (47) Parking brake control valvePilot oil pressure reducing valve (35) is mounted on the left side of the rear frame in the transmission compartment.Oil for the pilot circuit is supplied from hydraulic tank (44) to pilot and brake pump (39). The pilot oil flows through check valve (29) to pilot oil pressure reducing valve (35). Pilot oil pressure reducing valve (35) reduces the pilot and braking pump oil to the specified pilot pressure.
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(26) Selector and pressure control valveSelector and pressure control valve (26) is located on the left side of the rear frame in the transmission compartment.The pilot oil, now at a reduced pressure flows to selector and pressure control valve (26) and parking brake control valve (47) .While the pilot and braking pump is supplying oil to the pilot oil system, selector and pressure control valve (26) will block the flow of alternate oil into the pilot oil system.If the pilot and braking pump fails, or oil is not available, then selector and pressure control valve (26) will allow alternate oil to flow into the pilot oil system from the steering system and the main hydraulic system. When the engine is off, selector and pressure control valve (26) provides pilot oil to pilot control valve (16) via implement and steering solenoid valve (25) to lower the bucket. High pressure oil from the head end of lift cylinders (12) enters the pilot system through selector and pressure control valve (26). Selector and pressure control valve (26) reduces the oil pressure and lets lower pressure oil flow to pilot control valve (16) via implement and steering solenoid valve (25). When pilot control valve (16) is moved