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| Illustration 1 | g00545886 |
Schematic for the transmission hydraulic system (1) Flow control valve (2) Transmission control valve (3) Differential relief valve (4) Transmission oil filter (5) Converter backflow check valve (6) Transmission dump valve group (7) Transmission oil pump (8) Modulating valve (Torque converter lockup clutch) (9) Torque converter inlet relief valve (10) Torque converter lockup clutch (11) Torque converter (12) Suction screen and magnet (13) Transmission lubrication (14) Transmission oil cooler | |
The transmission hydraulic system consists of the following components: flow control valve (1) , transmission control valve (2) , differential relief valve (3) , transmission oil filter (4) , converter backflow check valve (5) (part of transmission hydraulic control valve (2) ), transmission dump valve (6) , transmission oil pump (7) , modulating valve (8) , torque converter inlet relief valve (9) , torque converter lockup clutch (10) , torque converter (11) , suction screen and magnet (12) and transmission oil cooler (14) .
The bottom of the transmission case provides the oil sump. Transmission oil pump (7) is a one-section gear type pump. Transmission oil pump (7) is a positive displacement pump. Pump (7) supplies oil to the power train hydraulic system. Oil is supplied to the pump inlet cavity through a tube that is mounted to the pump inlet and the transmission case. Before arriving at the pump, the oil flows through the suction screen and magnet (12) . Pressurized oil exits the pump outlet cavity. The pressurized oil flows to externally mounted transmission oil filter (4) . If there are any restrictions in the oil filter, a bypass valve in the oil filter housing allows the oil to flow around the filter. The oil then flows to flow control valve (1) in the transmission case and modulating valve (8) . Modulating valve (8) supplies oil to torque converter lockup clutch (10) . Flow control valve (1) sends 23 L/min (6 US gpm) of oil to transmission control valve (2) . The flow control valve supplies torque converter (11) with the remainder of the oil.
Spools in transmission control valve (2) send oil in order to engage the correct clutches for the selected speed and for the selected direction. One direction clutch and one speed clutch must be engaged in order to move the machine. Return oil from the transmission control valve can enter the torque converter circuit through converter backflow check valve (5) (part of transmission control valve (2) ). The higher pressure oil of the torque converter charging circuit is prevented by converter backflow check valve (5) from entering transmission control valve (2) . This occurs when the pressure of the transmission control valve is low during a shift.
Torque converter inlet relief valve (9) limits the pressure of the torque converter inlet to a maximum of 900 ± 70 kPa (130 ± 10 psi). Torque converter inlet relief valve (9) is installed in the transmission case below transmission control valve (2) . The transmission control valve must be removed in order to attain access to the torque converter inlet relief valve.
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| Illustration 2 | g01291514 |
Engine radiator (14) Transmission oil cooler | |
The outlet oil from the torque converter flows to transmission oil cooler (14) . The transmission oil cooler is part of the engine radiator. The oil from transmission oil cooler (14) provides lubrication to the transmission and cooling to the transmission. The lubrication oil flows into each transmission shaft. This is done in order to lubricate the bearings, the gears and the clutches. This is also done in order to cool the bearings, the gears, and the clutches.
Most of the oil passages are inside the transmission case and inside the body of the transmission control valve. The following lines are located outside the transmission case: transmission oil pump, transmission oil filter and transmission oil cooler.