ALTERNATOR-YM 5692772 - Caterpillar

Illustration 1 g03412178
Cross section of the straight travel control valve and the main relief valve
(1) Main control valve
(2) Left travel control valve
(3) Right travel control valve
(4) Passage
(5) Passage
(6) Check valve
(7) Check valve
(8) Passage
(9) Pilot passage
(10) Main relief valve
(11) Piston
(12) Straight travel control valve
(13) Return passage
(14) Line
(15) Line
(16) Line
(17) Drive pump
(18) Idler pump
(19) Pilot pump
(20) Valve
(21) Valve Oil from idler pump (18) enters main control valve (1) through line (15). Oil from drive pump (17) enters the main control valve through line (16). Drive pump oil and idler pump oil flow through check valves (6) and (7) to passage (8). The check valves ensure that only the higher oil pressure from the drive pump or from the idler pump flows through passage (8) to main relief valve (10).When the circuit pressure in passage (8) is lower than the pressure setting of the main relief valve, valve (20) is closed and valve (21) is closed. The closed valves do not allow oil to flow from passage (8) to return passage (13).
Illustration 2 g03035217
Main relief valve in the OPEN position during travel operation
(8) Passage
(9) Pilot passage
(11) Piston
(13) Return passage
(20) Valve
(21) Valve
(22) Adjuster
(23) Passage
(24) Spring
(25) Plug
(26) Passage
(27) Spring chamber
(28) Passage
(29) Valve chamber
(30) Spring During travel operation, the pilot oil pressure from pilot passage (9) flows through passage (23) and the pilot oil pressure acts on the top of piston (11). Piston (11) shifts to the right and the piston compresses spring (24) to close valve (20). Valve (20) is held in the closed position by force of spring (24).The initial rise in oil pressure at passage (8) causes valve (21) to shift upward against spring (30). The oil pressure in passage (8) flows in two paths.Some oil pressure flows to return passage (13) and some oil pressure flows through passage (26) into spring chamber (27). As oil pressure rises in spring chamber (27), the oil pressure will begin to act upon the top side of valve (21) and oil pressure will equalize on the top side and the bottom side of valve (21). Then, spring (30) will shift valve (21) down. Oil pressure in spring chamber (27) raises against valve (20). The force that is required for valve (20) to overcome spring (24) is higher during a travel operation. Spring (24) maintains the pressure setting of the relief valve.As the oil pressure in passage (8) increases to the relief pressure setting for the travel circuit, the oil pressure in passage (8) overcomes the force of spring (24). Oil pressure then shifts valve (20) up. The oil in spring chamber (27) flows to valve chamber (29). The oil in valve chamber (29) now flows through passage (28) to return passage (13) and the oil becomes low pressure.
Illustration 3 g03035239
Main relief valve in the OPEN position during implement operation or during swing operation
(8) Passage
(9) Pilot passage
(11) Piston
(13) Return passage
(20) Valve
(21) Valve
(24) Spring
(26) Passage
(27) Spring chamber
(28) Passage
(29) Valve chamber
(28) Passage
(30) Spring The main relief valve operates at a lower pressure during an implement operation or a swing operation.