PRIMARY POWERTRAIN CONTINUED
Powertrain Hydraulic System
Refer to Figure 2.
The powertrain hydraulic system uses a three-section oil pump. The oil pump is mounted on the gear case for the
bevel and transfer gears and is driven by an auxiliary drive shaft from the engine.
Torque Converter and Lubrication Section
Section (A) sends oil from the bevel gear case through a magnetic screen. The oil flows to the torque converter
inlet relief valve located in the lubrication distribution manifold. The torque converter inlet relief valve limits the
maximum oil pressure to the torque converter. The inlet relief valve sends most of the oil to the torque converter.
The rest of the oil is sent to the lubrication distribution manifold and is used to lubricate the brakes and the
The oil from the torque converter exits through the outlet relief valve. Next, the oil is routed to the oil cooler. Then,
the oil flows back to the lubrication distribution manifold. At the lubrication distribution manifold, the oil combines
with the oil that bypassed the torque converter.
The combined oil flows from the lubrication distribution manifold to lubricate the transmission and brakes and then
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 bearing
Transmission and controls section
Section (B) of the oil pump draws oil from the bevel gear case. The oil goes through a magnetic screen and flows
to the oil filter. Next, the oil flows to the brake control valve, the modulating valves, the accumulator, and main relief
valve. The main relief valve is located in the manifold on the top of the transmission and 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 (B) is for control of the brakes and the
Transmission and Torque Converter Scavenge Section
Section (C) removes oil from the torque converter and from the transmission. The oil goes through both screens
and it is used as lubrication for the steering differential and brake. The oil is then allowed to return to the bevel gear