INTRODUCTION 16000 SERVICE/MAINTENANCE MANUAL
1-68
Published 05-03-17, Control # 228-03
Retract Counterweight Lift Cylinder
When the counterweight lift cylinder switch is moved and
held in the retract position, an input signal from the wireless
transmitter is sent to a receiver on the crane. The receiver
sends the input signal to the Node-1 controller. Node-7
sends a 24 volt output to enable the counterweight lift
cylinder solenoids (HS-73 and 74) and shifts the valve to the
retract position.
The Node-3 controller also sends a variable 0 to 24 voltage
to enable the proportional relief solenoid HS-68 to provide
approximately 310 bar (4,496 psi) pressure to the
counterweight lift cylinder system.
Hydraulic pressure from the accessory pump flows through
the pressure control pilot valve, the three bank manifold
valve, and enters the free-flow check valve section of the
counterbalance valve. Fluid pressure on the rod end of the
lift cylinder retracts the cylinder to the desired length.
Hydraulic fluid from piston end of the lift cylinder is blocked
by the free-flow check valve section of the counterbalance
valve and the flow restraining section of the relief valve
preset for a relief setting of 152 bar (2,205 psi). The piston
end cylinder pressure opens the restraining section of the
counterbalance valve, allowing fluid to exit the valve. The
return hydraulic fluid passes through the three bank manifold
valve before returning to the crane hydraulic tank through the
return line.
When the retraction is reached, release the switch to lock the
cylinder in position. Hydraulic fluid at the piston end of the lift
cylinder counterbalance valve holds the lift cylinder in the
selected position.
When the switch is released, an input signal is sent to the
Node-1 controller. The Node-7 controller sends a zero volt
output to the hydraulic solenoids HS-72 and 73 to return the
valve to the center position.
The Node-3 controller sends a variable voltage output to the
accessory system proportional relief solenoid HS-68 to
provide approximately 207 bar (3,002 psi) system pressure.
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