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| Illustration 1 | g01821873 |
Right Side of Engine Compartment (1) Return manifold | |
Case drain lines from the propel pump, the propel motors, the vibratory pump, and the vibratory motors are connected to return manifold (1). Oil from the case drain lines is combined and directed to the thermal bypass valve inside the manifold.
The thermal bypass valve is a temperature transducer with a bypass spool and a relief valve. The temperature transducer controls the position of the bypass spool. The bypass spool controls the volume of oil that flows through the oil cooler. The relief valve limits the maximum pressure in the oil cooler to 310 kPa (45 psi).
When the hydraulic oil temperature is less than 54 °C (130 °F), the bypass spool is fully open. Under this condition, all the hydraulic oil is sent to the tank through the return line.
As the hydraulic oil temperature increases from 54 °C (130 °F) up to 66 °C (150 °F), the bypass spool shifts. The amount of the shift and therefore the amount of oil which is sent to the oil cooler depends on the temperature of the oil. When the hydraulic oil temperature reaches 66 °C (150 °F), the bypass spool is fully closed and the valve acts as the oil cooler bypass relief valve.
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| Illustration 2 | g01821874 |
Right Side of Engine (2) Charge filter (3) Pressure tap (4) S·O·S tap | |
Charge filter (2) is mounted on the right side of the engine. The engine compartment hood provides access to this component.
Oil from the steering pump flows through the fan motor and through charge filter (2). This oil is directed to the vibrator pump and to the propel pump.
The housing of the charge filter contains a bypass valve. If the pressure differential across the filter is greater than 310 kPa (45 psi), the bypass valve opens. When the bypass valve is open, charge oil flows to the hydraulic tank.
Pressure tap (3) provides a means of measuring hydraulic pressure downstream of the charge filter. S·O·S tap (4) provides a means of obtaining oil samples upstream of the charge filter.