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| Illustration 1 | g00690981 |
Schematic of power train hydraulic system (1) Priority valve (2) Wire harness for the electronic control module (3) Torque converter inlet relief valve (4) Oil filter for brakes and for transmission controls (5) Modulating valves and the main relief valve (transmission) (6) Brake control valve (7D) Steering differential and brake on the left side of the machine (7E) Planetary gears and brake on the right side of the machine (8) Passage for the lubrication of the transmission and the bevel gear (9) Oil cooler (10) Torque converter outlet relief valve (11) Torque converter (12) Power train oil pump (13) Pump drive (14) Passages to the steering differential, planetary gears and brake lubrication (15) Oil filter for the torque converter (16) Check valve (A) Transmission and controls section (B) Torque converter and lubrication section (C) Transmission and torque converter scavenge section | |
The power train hydraulic system uses pump (12). The pump consists of three sections.
Oil pump (12) is mounted on the implement hydraulic pump. The shafts of the two pumps are connected by splines. The pump is driven from the engine by gears in the flywheel housing. The bevel gear case is the sump for the power train hydraulic system.
Transmission and Controls Section
Section (A) of pump (12) draws oil from the bevel gear case. This pump section supplies the high pressure circuit. The oil flows through oil filter (4). Next, the oil flows to the modulating valves, main relief valve (5), and brake control valve (6). The main relief valve is located in the manifold on the top of the transmission. The main relief valve controls the pressure in the circuit.
The oil that flows past the main relief valve provides part of the lubrication and cooling for the transmission and bevel gear. The primary use of oil from section (A) is for control of the transmission clutches and of the brakes.
Torque Converter and Lubrication Section
Section (B) sends oil from the bevel gear case through oil filter (15) to priority valve (1). This pump section supplies the low pressure circuit. The priority valve sends a portion of the oil to torque converter (11). The rest of the oil is used to lubricate the brakes and the transmission.
The oil from torque converter (11) exits through outlet relief valve (10). Next, the oil is routed to oil cooler (9). Then, the oil flows back to priority valve (1). At the priority valve, the oil combines with the oil that bypassed torque converter (11) .
The combined oil flows from priority valve (1) in order to lubricate the transmission and brakes. Then, the oil drains to the bevel gear case. A small portion of the oil is diverted from the torque converter inlet in order to lubricate the drive gears and bearings.
Priority valve (1) routes oil from section (B) of pump (12) to torque converter (11). Signals from the electronic control module (ECM) to the priority valve can divert oil from section (B) through check valve (16). The oil flow from section (B) adds to the flow from section (A). Oil pressure increases until a minimum pressure is achieved for controlling the transmission and brakes (7) .
Torque converter inlet relief valve (3) is located in priority valve (1). Torque converter inlet relief valve (3) limits the maximum oil pressure to torque converter (11) .
Scavenge Section
Section (C) removes oil from torque converter (11) and from the transmission. The oil is returned to the bevel gear case. The oil is drawn through screens at torque converter (11) and at the transmission.