Loading Instructions; Hydraulic System - Vestil CBS Series Instruction Manual

LOADING INSTRUCTIONS

The capacity of the unit appears on label 287 (see p. 19). DO NOT apply a load to the forks that exceeds the capacity.
When loading the stacker, always follow these guidelines:
1. The load should firmly contact the upright portions of the forks;
2. DO NOT apply a load to the tips of the forks;
3. Center the load on the forks;
4. Only transport loads in the lowered position.

HYDRAULIC SYSTEM:

NOTE: AC powered units must be plugged into a wall outlet via the flanged inlet (see FIG. 10 on p. 10).
The lift cylinder can be controlled with either a handheld
pendant controller or the push buttons in the housing of the
modular power unit. To raise or lower the fork carriage:
a) Push buttons on MPU: press the button marked "RAISE"
or "LOWER".
b) Handheld controller: press the white (raise) button to
raise the forks. The black (lower) button lowers the forks.
SEQUENCE OF OPERATION:
Pressing either raise button activates the electric motor. The
motor turns the hydraulic pump, which draws oil out of the
reservoir (inside the power unit). Oil flows through a suction filter
and into the pump. Pressurized oil then flows from the pump,
through a check valve (to prevent back flow when the pump is
not running), and into the cylinder. Oil remains in the cylinder
allowing the forks to maintain elevation after the raise button is
released.
If the weight of the load applied to the forks exceeds the
capacity of the stacker, the forks will not rise even though the
raise button is pressed. Pressure will increase in the hydraulic
circuit between the pump and the cylinder. When pressure
reaches a preset level, a relief valve unseats and allows oil to
circulate back to the reservoir. Redirecting oil during an overload
situation prevents oil pressure from continuing to increase.
Extremely high pressure might damage the hydraulic system.
To lower the forks, press the lower button. This energizes the lowering solenoid valve coil, unseats the poppet valve,
and allows oil to return to the reservoir. As oil flows from the cylinder, it passes through a pressure compensated flow
control valve (PCFC). The PCFC restricts the amount of oil leaving the cylinders. Governing flow ensures that the forks
descend at a constant, controlled rate.
Releasing the DOWN button de-energizes the solenoid and closes the valve poppet. Both the closed poppet and the
check valve work to prevent oil from returning to the reservoir. Consequently, the cylinder stops retracting and the forks
maintain their positions.
LOWERING SOLENOID VALVE:
Your stacker is equipped with a cartridge lowering valve. If a malfunction occurs while lowering the fork carriage, refer
to the solutions presented in "Troubleshooting" on p. 15-16. To clean the lowering solenoid, follow this procedure:
1. Completely lower the fork carriage.
2. Use a sharp object, like a small screwdriver, to push the poppet in from the bottom and open the valve.
3. Repeat several times while immersing the valve in kerosene or mineral spirits. Blow the cleaned valve dry.
4. Blow compressed air through the valve while holding the valve open as described in step 2.
5. Inspect the O-rings and the PTFE washer (polytetrafluoroethylene). If either component is damaged, replace it.
6. Reinstall the valve. The valve should be tightened to approximately 20ft·Ib of torque.
VELOCITY FUSE:
A brass velocity fuse with a stainless steel spring can be found in the base of the cylinder. If a hose or fitting fails,
hydraulic pressure drops and the forks lower rapidly. As soon as the descent speed exceeds a preset speed, the velocity
fuse activates to cease oil flow. Consequently, the forks will not lower until hydraulic pressure is reestablished. Always
unload the forks if the velocity fuse activates.
Copyright 2017 Vestil Manufacturing Corp.
rev. 1/16/2017 CBS, MANUAL.doc
HYDRAULIC SYSTEM DIAGRAM:
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