PIN 2405949 - Caterpillar

PTO Hydraulic System
Illustration 8 g00470954
Low pressure hydraulic system (1) Brakes (2) PTO clutch (3) PTO valve (4) Brake valve (5) Solenoid for PTO (6) Transmission oil filter (7) Filter bypass valve (8) Passage to the charge circuits for implement and steering (9) Tandem charge pump (10) Common sump (11) Oil suction screen (12) Regulator valve (13) Steering pump (14) Pump drive housing (15) Implement hydraulic pump (16) Transmission cooler (17) Cooler bypass valve (18) Lube relief valve (19) Creeper valve (20) Pressure regulating valve (21) Passage to transmission solenoids (22) Passage to clutch lube (23) Transmission hydraulic control (24) Orifice (25) Passage for lube oil to PTO (CC) Second pressure reduction (EE) Pilot oil (FF) Reduced pilot oil (KK) Sump oilThe hydraulic system for the PTO is a low pressure circuit. Oil is drawn out of common sump (10) and through oil suction screen (11) to the intake of tandem charge pump (9). Oil then passes through the small section of the tandem charge pump. Oil from the tandem charge pump is then routed through transmission oil filter (6). The filtered oil either flows to oil cooler (16) or the filtered oil flows across cooler bypass valve (17). Next, the oil flows to transmission hydraulic control (23) that is located on the center housing of the transmission. Pressure regulating valve (20) is located in the transmission hydraulic control. Pressure regulating valve (20) maintains a constant pressure of 1825 70 kPa (265 10 psi) in the following low pressure circuits: transmission circuit for clutch operation, service brake circuit and circuit for clutch solenoids. The remaining flow that is not required by the above circuits is directed into the following circuits: PTO, lube oil for the PTO and transmission lube.Lube oil flow for the PTO clutch is 10 L/min (2.6 US gpm) at a pressure of 206 kPa (30 psi). The lube oil flow is maintained by a 3 mm (0.125 inch) orifice that is located in the transmission hydraulic control. The excess oil flow that is not required by the PTO is directed to the transmission oil cooler. The oil that has been routed through the transmission oil cooler is then routed as lube oil for the clutches in the transmission. The transmission oil cooler is located in front of the engine radiator. The lube oil may be checked by placing a fitting at the inlet port on the left side of the retainer plate for the PTO.PTO Valve and Clutch Operation
Illustration 9 g00470955
Hydraulic circuit for a disengaged PTO (1) Solenoid (2) Inlet for supply oil (3) Pilot pressure (4) Retainer (5) Orifice (6) Valve spool (7) Brake band (8) Passage for lube oil (9) Clutch pack (10) Input shaft (11) Input hub (12) Clutch housing (13) Lever (14) Brake band (15) Brake piston (CC) Second pressure reduction (EE) Pilot oil (FF) Reduced pilot oilThe oil in the hydraulic circuit for the PTO separates in two directions at a tee. One passage of oil flows to solenoid (1) that