Baoli CPCD 80, Инструкция по эксплуатации и обслуживанию

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2.6 Hydraulic circulation system (see Fig. 2.7)
When the engine is started and the charging pump is put into operation, the torque
converter fluid in the oil tank (transmission case) is forcibly sent to the control valve from
the pump through the strainer.
The fluid sent from the charging pump is divided to two directions in the torque
converter case, one for torque converter and the other for transmission.
Pressure of the fluid for clutch is adjusted to 1.2 to 1.5 MPa with the relief valve.
And then it is supplied to the control valve. Pressure of the fluid divided for the converter
is adjusted to 0.5 to 0.7 MPa with the converter relief valve. After that this fluid reaches
the wheel of torque converter. After it is cooled by the oil cooler, it lubricates the clutch
group and then returns to the oil tank through the filter.
When the selector valve is in neutral position, the circuit from the selector valve to
the clutch is closed. Therefore the fluid is joined with the torque converter filling fluid.
When the selector spool is set to the forward or reverse position, fluid flows into the
accumulator due to action of modulate valve, so that pressure rises gradually. During
this time the clutch starts to engage.
When the accumulator is filled with fluid, hydraulic pressure rises intensively so that
the hydraulic clutch is completely engage. While the forward or reverse clutch is
operating, another clutch is rotating between the sintered plates and the steel plates.
Therefore this part is lubricated with oil sent from the oil cooler to prevent seizure of
plates.
When the brake pedal is depressed and the inching valve is actuated, most of
hydraulic oil supplied to the clutch is drained from the inching valve and returns to the
transmission case. The fluid for the torque converter circulates in the same manner as
in neutral state.