INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-94
Published 11-06-15, Control # 040-13
Counterweight Switch
The counterweight switch is operative only in Standard or
Setup modes. It allows the counterweight strap cylinders to
be disconnected from counterweight straps during
assembly/disassembly.
Power is available to MAX-ER remote switch assembly when
power cable (W28) is plugged into receptacle at left side of
counterweight trailer and engine is running. When power
button on MAX-ER remote switch assembly is pressed,
power is enabled to operate counterweight switch. The
switch is spring-returned to OFF position. In off position, the
counterweight strap cylinders solenoid valve is “motor
spooled” with both cylinder ports and tank port connected to
the spool center position. This prevents premature opening
of counterbalance valves.
Counterweight Strap Cylinders Lower
When counterweight switch is held in the DOWN lower
position (extend cylinder), an input signal is sent to the PC. A
12-volt output signal from PC enables the counterweight
strap cylinder lower solenoid valve HS-41. Internal pilot
supply pressure of 200 psi (14 bar) enables selected spool to
shift the counterweight strap cylinder solenoid valve. The
crane PC sends an output signal to shift crane auxiliary
system disable valve HS-12, to block valve bypass.
Accessory system pressure increases to operate accessory
items. Accessory system fluid enters MAX-ER accessory
valve and flows through to free-flow check valve section of
counterbalance strap cylinder valves, entering piston end of
the strap cylinders to start extending the cylinder rods.
Fluid from rod end of cylinders is blocked by free-flow check
valve section of counterbalance valve and flows through the
flow restraining section that has a relief setting of 1,600 psi
(110 bar). Return hydraulic fluid then exits counterbalance
valve and passes through MAX-ER accessory valve before
returning to crane hydraulic tank through return line. Release
counterweight switch to OFF to lock the strap cylinders in
position.
Counterweight Strap Cylinders Raise
When counterweight switch is held in the UP raise position
(retract cylinder), an input signal is sent to the PC. A 12-volt
output signal from PC enables the counterweight strap
cylinder raise solenoid valve HS-40. Internal pilot supply
pressure of 200 psi (14 bar) enables selected spool to shift
the counterweight strap cylinder solenoid valve. The crane
PC sends an output signal to shift crane auxiliary system
disable valve HS-12, to block valve bypass. Accessory
system pressure increases to operate accessory items.
Accessory system fluid enters MAX-ER accessory valve and
flows through to free-flow check valve section of
counterbalance strap cylinder valves, entering rod end of the
strap cylinders to start retracting the cylinder rods. Fluid from
piston end of cylinders is not blocked by the counterbalance
valve and exits to MAX-ER accessory valve before returning
to crane hydraulic tank through return line. Release
counterweight switch to OFF to lock the strap cylinders in
position.
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