FLYWHEEL AS 2146832 - Caterpillar

Illustration 1 g00847892
Cross section of straight travel control valve and main relief valve (1) Straight travel control valve (2) Main control valve (3) Right travel control valve (4) Check valve (5) Check valve (6) Main relief valve (7) Delivery line (drive pump) (8) Delivery line (idler pump) (9) Drive pump (10) Idler pump (11) Internal passageMain relief valve (6) is located in the left side of the main control valve. The main relief valve limits the maximum operating pressure of the travel hydraulic circuit and the implement hydraulic circuits when the machine is at a load condition.The oil delivery from idler pump (10) enters main control valve (2) through delivery line (8). The oil delivery from drive pump (9) enters main control valve (2) through delivery line (7). Oil from the idler pump and the drive pump flow through check valves (4) and (5) to passage (11). Check valves (4) and (5) ensure that only the higher oil pressure from the idler pump or the drive pump flows through passage (11) to main relief valve (6) .Closed Position
Illustration 2 g00677421
Main relief valve (closed position) (11) Passage (12) Seat (13) Valve (14) Spring (15) Spring chamber (16) Seat (17) Poppet (18) Spring (19) Passage (20) Orifice (21) Return passagePoppet (17) is positioned to the left against seat (16) by the force of spring (18). Valve (13) is positioned to the left against seat (12) by the force of spring (14) .System pressure oil in passage (11) flows through orifice (20) into spring chamber (15). The force of the system pressure oil acts on poppet (17). When the force of system pressure oil in passage (11) is less than the force of spring (18), poppet (17) remains against seat (16). The pressure in passage (11) and the pressure in spring chamber (15) are now equal. System pressure oil in spring chamber (15) and the force of spring (14) maintain valve (13) against seat (12). There is no oil flow from passage (11) to return passage (21). When main pump oil pressure in passage (11) is less than the main relief pressure setting, main relief valve (6) remains in the closed position.Open Position
Illustration 3 g00677470
Main relief valve (open position) (11) Passage (12) Seat (13) Valve (14) Spring (15) Spring chamber (16) Seat (17) Poppet (18) Spring (19) Passage (20) Orifice (21) Return passage (22) Passage (23) Valve chamber (24) Locknut (25) Adjustment screwSystem oil pressure in passage (11) and spring chamber (15) nears the main relief valve pressure setting. The force of the system oil pressure in spring chamber (15) becomes greater than the force of spring (18). Poppet (17) away from seat (16). System oil pressure now flows through seat (16) into valve chamber (23). The oil in valve chamber (23) now flows through passage (22) into return passage (21). This low pressure oil now returns to the hydraulic tank.At the same time as the oil in spring chamber (15) flows through seat (16), the system pressure oil in passage (11) flows through