INTRODUCTION 16000 SERVICE/MAINTENANCE MANUAL
1-60
Published 05-09-17, Control # 014-28
Telescopic Beam Cylinder
See Figure 1-55 and Figure 1-56 in the following procedure.
The telescopic beam cylinder connects the wheeled
counterweight assembly to the crane. The beam can be
positioned to three different positions depending on crane
configuration.
The telescopic beam has a counterbalance valve at each
cylinder port to provide smooth operation when operating.
Counterbalance valves lock cylinder in position. and also
provide relief protection for the cylinder. The telescopic beam
three position spool valves are motor spooled where both
cylinder ports and tank port of valve spool section are
connected in center position.
Top and bottom telescopic beam position encoders detect
telescopic beam position and direction of beam movement.
Node-1 controller receives this input information as two out-
of-phase square wave voltages that are converted to counts.
Information screen in operator’s cab indicates telescopic
beam extend position in inch or metric.
Power is available to hand-held wireless remote control
when, engine is running, MAX-ER function mode is selected,
and power button is pressed. Telescopic beam can not be
extended/retracted until electrical cables and hydraulic lines
are connected between rear of crane and telescopic beam of
MAX-ER.
Telescopic Beam Cylinder Extend
When telescopic beam switch is moved and held in extend
position, an input signal from wireless transmitter is sent to a
receiver on the crane. The receiver sends the input signal to
Node-1 controller. Node-7 sends a 24 volt output to enable
the telescopic beam solenoid HS-88 and shifts the valve to
extend position.
Node-3 controller also sends a variable zero to 24 voltage to
enable proportional relief solenoid HS-68 to provide
approximately 4,500 psi (310 bar) pressure to telescopic
beam system.
Hydraulic pressure from accessory pump flows through
pressure control pilot valve, three bank manifold valve, and
enters free-flow check valve section of counterbalance
valve. Fluid pressure on piston end of beam cylinder extends
the beam to the desired length.
Hydraulic fluid from rod end of beam cylinder is blocked by
free-flow check valve section of counterbalance valve and
flow restraining section of relief valve preset for a relief
setting of 2,200 psi (152 bar). Rod end cylinder pressure
opens restraining section of counterbalance valve, allowing
fluid to exit valve. Return hydraulic fluid passes through three
bank manifold valve before returning to crane hydraulic tank
through return line.
When desired beam extension is reached, release switch to
lock cylinder in position. An input signal is sent to Node-1
controller. Node-7 controller sends a zero volt output to
hydraulic solenoid HS-88 to return valve to center position.
Node-3 sends a variable voltage output to accessory system
proportional relief solenoid HS-68 to provide approximately
3,000 psi (207 bar) system pressure.
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