(3)
The pump is an inline piston type with a fixed displacement. The pump has a centrifugal boost pump to supply fluid under pressure to the inline pump. This allows the PTU pump to operate at low supply pressure. The pump moves fluid through the pump case to lubricate and cool the pump. The case drain fluid flows into the left system return line.
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MAINTENANCE MANUAL
LEFT MAIN
WHEEL WELL SEE A
PTU PRESSURE FILTER MODULE
UNIT (PTU) POWER TRANSFER
FILTER MODULE PTU CASE DRAIN
Power Transfer Unit (PTU) System LEFT MAIN WHEEL WELL A Figure 1 (Sheet 1) FWD OUTBD
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MAINTENANCE MANUAL
RIGHT MAIN WHEEL WELL
Power Transfer Unit (PTU) System
Figure 1 (Sheet 2)
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MAINTENANCE MANUAL
(4)
A bearing wear indicator is on the motor portion of the PTU. A red button on the indicator will pop out to give a visual warning if the main pump bearing wear exceeds limits.
B.
PTU Pressure Filter Module (Fig. 3)
(1) The PTU module filters the pump pressure flow before the fluid
enters the left system. The filter module is next to the PTU, in
the left wheel well. The module has a disposable filter element. A
differential pressure indicator shows when the filter is blocked. A
spring-loaded valve in the module prevents fluid draining when the filter element is removed. The module has a check valve, a control pressure switch, and an indication pressure switch.
HYDRAULIC PUMP
LEFT SYSTEM SUPPLY
LEFT SYSTEM PRESSURE
PUMP CASE DRAIN
SUMP DRAIN WEAR INDICATOR
BEARING
HYDRAULIC MOTOR
RIGHT SYSTEM CASE DRAIN
RETURN HYDRAULIC
MOTOR UP
RIGHT SYSTEM FWDPRESSURE
Power Transfer Unit (PTU)
Figure 2
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C. PTU Case Drain Filter Module (Fig. 3)
(1) The PTU case drain filter module consists of a disposable filter element, a differential pressure indicator, a check valve, a relief valve, and a spring-loaded shutoff valve. The element filters case drain fluid from the PTU pump. The differential pressure indicator shows when the filter is blocked. The check valve prevents reverse flow when the left system is pressurized. The relief valve opens to allow fluid to bypass the filter, if the filter becomes plugged. When the filter case is removed, the shutoff valve and check valve prevent loss of fluid. The filter module is in the left main wheel well, next to the PTU.
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