SECTION 9
HYDRAULIC SYSTEM
p. 9-3
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9.2 Operation
The hydraulic system operates at HI or LO pressure settings up to the
maximum flow capacity of the variable displacement piston pump. Upon
selecting HI or LO, the operator is able to adjust the HI or LO pressure
controls within the respective adjustment ranges. Note that for SLIV
pumps having proportional pressure control, the discussion of HI/LO
controls does not apply. Instead the proportional pressure control is
used to increase/decrease hydraulic pressure on the pump.
The electric motor (7) drives the variable displacement, pressure
compensated pump (6). The hydraulic manifold (5) is mounted on the
pump discharge. The flow from the pump passes through a check valve
to the directional control valve (8), and the directional control valve sends
the flow to the hydraulic cylinders (9) in one direction until the piston
activates the proximity switch at the end of the stroke. The activated
proximity switch sends an electrical signal to the programmable
controller (PLC). This PLC in turn activates the directional control valve
(8) to change flow and to reverse direction of movement of piston until
activating the opposite end-of-stroke proximity switch.
Although one DCV supplies hydraulic power to two intensifier hydraulic
cylinders arranged in parallel, these cylinders operate at approximately
the same cycle rate due to logic built into the PLC (see Section 8,
Electrical System).
9.2.1 Hydraulic Pressure Adjustment
A variable displacement pressure compensated feature maintains
constant operating pressures even under variable flow demands. Dual
pressure control is standard. Switching high to low pressure may be
done at the control panel (or remotely) with the HI-LO switch that
activates the solenoid valve (10). The HI pressure is set by adjusting the
knob (1) and the LO pressure is adjusted using a wrench on that relief
cartridge (2). Turning the knob/adjusting the screw clockwise increases
pressure.
NOTE
In order to remote select the pressure, the remote/local switch
should be set to the “REMOTE” position.
Proportional pressure controls are typically located at an operator’s
station that is remote from the SLIV intensifier pump.
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