TM 5-3895-382-24
For early pumps, the maximum working pressure for closed
circuit loop line (4) is limited to 18 982 kPa (2755 psi) above
return loop pressure by high pressure relief valve (16). For late
pumps, the maximum working pressure for dosed circuit loop
line (4) is limited to 25 000 kPa (3625 psi) above return loop
pressure by high pressure relief valve (16). When the circuit
pressure increases to the high pressure relief valve setting, oil
passes from the closed circuit loop line into the charge circuit.
The oil then returns to hydraulic oil tank (13) or into the low
pressure side of the loop to prevent cavitation of the pump.
When the vibratory system is being operated, the return loop
pressure is limited to 1725 345 kPa (250 20 psi) by cooling
relief valve (2). High pressure oil in closed circuit loop line (11)
moves the shuttle valve spool inside vibratory flushing valve
(10) from centered position and hot, low pressure oil in closed
circuit loop line (4) flows through vibratory flushing valve (10).
The oil flows through cooling relief valve (2) and the hydraulic
oil cooler before entering the hydraulic oil tank. Fresh charge
oil enters low pressure closed circuit loop line (4) through
check valve (12), compensating for oil loss through the
vibratory flushing valve and internal leakage.
Oil which passes from the dosed circuit into the vibratory pump
and motor cases is returned to the hydraulic oil tank.
13-24
