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| Illustration 1 | g00388197 |
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 steering and implement (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 (GG) Second pressure reduction (EE) Pilot oil (FF) Reduced pilot oil (LL) Sump oil | |
The hydraulic system for the transmission 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. The lubrication and cooling of the speed clutches requires 5.8 ± 1.9 L/min (1.50 ± 0.50 US gpm) of oil flow. The lubrication and cooling of the direction clutches requires 47.3 ± 9.5 L/min (12.5 ± 2.5 US gpm) of oil flow. 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 filter bypass valve will open if there is a pressure differential between the inlet and the outlet of the filter that is greater than 345 kPa (50 psi). The filter bypass valve contains a 12 volt switch that is normally closed. If the filter bypass valve opens, the unfiltered oil that enters the transmission circuit will cause the switch to open. The switch will then signal the Electronic Monitoring Center (EMC). The EMC will recognize a noncritical event if the switch remains open for more than 8 seconds. The indicator lamp for filters will illuminate on the EMC. A F392 fault code will be logged. Also, the EMC will record the engine hours as the fault is logged. The indicator lamp will continue to flash if the filter is bypassing.
Note: The EMC will not recognize a transmission oil filter that is bypassing as a noncritical event if the temperature of the hydraulic oil is less than 35°C (100°F). However, the indicator lamp for the filters will flash.