J&M 44-50 Operating And Maintenance Manual page 38

MODEL 44-50
VIBRATORY
DRIVER/EXTRACTOR
V. HYDRAULIC CIRCUITRY
B. VIBRATOR DRIVE (CONTINUED)
Full motor speed is reached within a few seconds and the motor drive pressure is indicated
by GAGE (GA1). Maximum drive pressure is limited to approximately 5000 PSI (345 Bar)
by the FORWARD RELIEF VALVE (RV1). The FORWARD RELIEF VALVE (RV1), if opened
by over pressure, permits a small pilot fl ow from cartridges (CB1 AND CA2). This pilot
fl ow causes cartridges (CB1 and CA2) to partially open and allows some or all of the pump
fl ow to return to the reservoir. Oil exiting VIBRATOR MOTORS (M) open cartridge BV and
returns to the power unit. Cartridge BV opens easily because its pilot fl ow is "vented" by
BRAKE VALVE (RV5). BRAKE VALVE (RV5) is held open by pressure coming from the
motor drive FORWARD system. Case drain oil from the motors returns to the reservoir.
Case drain pressure is limited to 50 PSI (3.4 Bar) by the CASE DRAIN RELIEF VALVE
(RV3). Oil returning to the power unit opens cartridge CB2 and returns to the reservoir
through COOLER VALVE (V3), HEAT EXCHANGER (HE) and RETURN FILTERS (F2).
Cartridge CB2 opens easily because its pilot fl ow is "vented" by CONTROL VALVE (V2).
Returning the Vibrator Switch to the center position de-energizes control valve (V2), and
again opens cartridges CA1 and CB1 which allows pump fl ow to return to the reservoir
without driving the vibrator. When the Model 580 Power pack is used with the 44-50 Vibrator
the RELIEF VALVE (RV4) is set at 4800 PSI. When pressure is removed from the drive
FORWARD system, the BRAKE VALVE RELIEF (RV5) closes and blocks the pilot fl ow
BRAKE VALVE (BV) cartridge and causing it to close. Maximum brake pressure generated
by BRAKE VALVE (BV) is limited by BRAKE VALVE RELIEF (RV5) to 2000 PSI (138 Bar).
This 2000 PSI (138 Bar) back pressure rapidly brakes the motors (M) to a stop.
Hydraulic oil temperature is regulated by the COOLER VALVE (V3). When oil temperature
is below 100°F (38°C), V3 directs the fl ow directly to the reservoir through FILTER (F2).
When oil temperature exceeds 100°F (38°C), COOLER VALVE (V3) directs fl ow through the
HEAT EXCHANGER (HE) before it enters the reservoir, through FILTER (F2). Excessive
pressure in the HEAT EXCHANGER (HE) is prevented by CHECK VALVE (CV3), which
bypasses excess fl ow and limits pressure to 65 PSI (4.5 Bar).
The quick-disconnect couplers (QD1, QD2, and QD5) permit de-coupling of the drive and
case drain hoses at the power unit.
INSTRUCTIONS
V-2
OPERATING