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MODEL 220
HYDRAULIC
IMPACT HAMMER
V.
HYDRAULIC CIRCUITRY
A. DRIVE PUMP
With the diesel engine running, hydraulic oil is taken from the reservoir by the drive
pump (P1). The drive pump flow returns to the reservoir as long as the drive switch
remains in its NEUTRAL position.
Turning
the
DIRECTIONAL CONTROL VALVE (V2) directing the pump flow to the hammer
through a 1.25" hose.
PRESSURE GAGE (GA1). Maximum drive pressure is limited to approximately
4540 PSI (303 Bar) by the drive pressure RELIEF VALVE (RV1).
disconnect couplings (QD1 and QD2) permit de-coupling of the drive hoses at the
power unit.
The CONTROL VALVE (V3), in the hammer, sends the pump flow directly to the
lower (rod end) of the CYLINDER (CYL).
pressure to the DUMP VALVE (DV) holding it closed. The ram lifts. Additional
hydraulic oil, stored under pressure in the PRESSURE ACCUMULATOR (A1), adds
to the pump flow causing an upward velocity of the ram that is greater than the
pump flow, alone, would generate. As the CYLINDER raises the ram, oil in the
upper (blind end) of the CYLINDER is exhausted back to the power unit through a
1.50" return hose. Flow resistance in the return hose causes a portion of this
exhaust flow to be, temporarily, stored in the TANK ACCUMULATOR (A2).
As the ram nears the top of its stroke, the trip bar activates the TRIP VALVE (V4),
which is hydraulically connected to the main pump flow via check valve CV6.
Activating the TRIP VALVE directs a pressure signal to shift the CONTROL VALVE
(V3). Pump flow is disconnected, and blocked, from the rod end of the CYLINDER
when the CONTROL VALVE shifts. Shifting the CONTROL VALVE also removes
pressure from the DUMP VALVE, which opens, and allows the ram to fall. High
upward velocity of the ram, however, causes it to continue upward movement,
decelerating, even after the DUMP VALVE is opened. While the CYLINDER is
decelerating to a stop, the rod end is kept full of oil by REPLENISHMENT CHECK
valve (CV4).
FORWARD/REVERSE
Hammer operating pressure is indicated by the drive
V-1
switch
to
FORWARD
The CONTROL VALVE also sends
operates
the
The quick-
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