Case 580SR Service Manual page 176

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110 SECTION 21 - TRANSMISSION
2.7 OPERATION
The transmission and hydraulic torque converter of the power train enacts an important role in transmitting en-
gine power to the driving wheels. In order to properly maintain and service these units it is important to first
understand their function and how they operate.
The transmission and torque converter function together and operate through a common hydraulic system.
With the engine running, the transmission charging pump draws oil through the oil suction filter and directs it
through the oil filter and pressure regulating valve.
Across the oil filter is a filter by-pass valve which will open if the pressure difference becomes higher than
4.3 bar.
The pressure regulating valve maintains pressure for the control valve and clutches at 20 bar.
Excess oil volume is bled off into the converter system. A safety valve is fitted between the pressure regulator
and converter.
The valve will open if pressure in this system becomes higher than 10 bar.
After entering the converter the oil is directed through the converter blade cavity and exits in the passage be-
tween the turbine shaft and pump drive shaft. Flows to the cooler.
After leaving the cooler the oil is directed to a fitting on the transmission.
Then through a series of tubes and passages lubricates and cools the transmission bearings and clutches.
The oil then gravity drains back to the transmission sump.
Across the converter and oil cooler is a converter by-pass valve which will open if the pressure difference is
higher than 4 bar (during start up from cold or at high rpm).