TUBE-EXHAUST 2389979 - Caterpillar

Illustration 1 g03324839
(1) Travel motors (2) Swing motor (3) Case drain line (4) Case drain line (5) Main control valve (6) Case drain line (7) Makeup line (makeup oil to swing motor) (8) Hydraulic oil cooler (9) Bypass check valve (10) Slow return check valve (11) Return passage (12) Bypass cut spool (drive pump) (13) Bypass cut spool (idler pump) (14) Passage (15) Passage (16) Return line (17) Hydraulic tank (18) Return filter (19) Case drain filter (20) Pilot pump (21) Idler pump (22) Drive pump (23) Case drain line (24) Suction lineThe oil delivery from idler pump (21) and drive pump (22) enters main control valve (5) . The oil then flows to return passage (11) and return line (16) in one of the following manners.When all joysticks and/or travel levers/pedals are in the NEUTRAL position, pump low pressure standby oil from drive pump (22) flows through passage (14) and bypass cut spool (12) to return passage (11) . Pump low pressure standby oil from idler pump (21) flows through passage (15) and bypass cut spool (13) to return passage (11) . From return passage (11) the return oil flows through slow return check valve (10) , hydraulic oil cooler (8) , and returns to the hydraulic tank.When any one of the joysticks and/or travel levers/pedals is shifted from the NEUTRAL position, bypass cut spool (12) and/or bypass cut spool (13) shifts to the closed position. Pump oil is then directed to the cylinders and/or motors. The return oil from the cylinders and/or motors now flows through the cylinder-to-tank spool or motor-to-tank spool and returns into passage (11) . From return passage (11) the return oil flows through slow return check valve (10) , hydraulic oil cooler (8) , and returns to the hydraulic tank.When the oil temperature is very low, most of the oil is returned through bypass check valve (9) to hydraulic tank (17) . The remainder of the oil flows into oil cooler (8) and return filter (18) to hydraulic tank (17) .When the oil temperature increases, the rate of oil flow through bypass check valve (9) decreases. This action causes the rate of oil flow through oil cooler (8) to increase.ReferenceFor more information concerning the bypass check valve, refer to Systems Operation, "Bypass Valve (Return)".Case drain oil from idler pump (21) , drive pump (22) , and pilot pump (20) flows into case drain line (23) . Case drain oil then flows from line (23) to case drain filter (19) and into hydraulic tank (17) . Case drain oil from swing motor (2) and travel motors (1) flows into respective case drain lines (6) and (3) . The case drain oil then combines and flows through the case drain line (4) . The case drain oil from case drain line (4) then flows through case drain filter (19) and into the hydraulic tank.Makeup line (7) will route return oil to the inlet port of the swing motor if a vacuum condition occurs at the