TM 5-1730-245-14
1.14. CIRCUIT DESCRIPTION (Figure 1-4).
1.14.1 Pressure system. Hydraulic oil is drawn from the reservoir (1) to the common inlet of the dual hydraulic
pump (2). Two hoses then direct the output of the two independent pump sections to a manifold block. The
manifold block contains two relief valves (3) and (4), the thermal diverter valve (14), and controls the required
flow paths. The relief valves (3) and (4) are used to control the pressure in each system independently. They
are externally adjustable and are normally set to limit the maximum pressure at 2800 psi The two fluid systems
from the manifold block are directed to the quick disconnects at the front of the unit The system outlets are
labeled as circuit #1 and circuit #2. Each outlet system is connected to return to the reservoir, by one of the
panel mounted valves (5) or (6), which serve to unload its system pressure to the reservoir when opened.
Valve (9) must be in the open (bypass) position for this to occur. If valve (9) is in the "CIRCUIT NO 3
PRESSURE" position when the selector valves (5) and (6) are in the "CIRCUIT NO. 3 16 GPM" position, the
combined output of the two pump sections is available at the third outlet port (10) at the front of the hydraulic
power supply. This outlet is labeled circuit #3
1.14 2 Return system. Each system has its own return port (11),(12) and (13) which are identified by labels.
The return flows are directed in the unit to the hydraulic control manifold where they are diverted to the
reservoir through a return filter (16). The thermal valve (14) channels the return flow either through the cooler
(15) or bypasses it depending on the return fluid temperature. The thermal valve is set to start diverting the
fluid through the cooler at 105 degrees F.
1.14.3 Safety limits. A temperature switch in the hydraulic system (19) will shut down the engine if the
hydraulic fluid temperature exceeds 160 degrees F. Additional limit switches on the engine will also cause
engine shutdown if the engine overheats (21) or in the event of oil pressure failure (20)
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