Manitowoc Published 11-06-15, Control # 040-13 1-67
2250 SERVICE/MAINTENANCE MANUAL INTRODUCTION
Boom Butt Handling Cylinder Retract
When power button is pressed and boom butt cylinder switch
is held in the down retract position, an input signal is sent to
the PC. The PC sends a 12 volt output signal to auxiliary
system disable relief valve HS-12 that adjust system
pressure to 3,500 psi (241 bar).
Boom butt cylinder engage solenoid HS-16 is enabled by the
PC to shift the solenoid valve in the retract position.
Hydraulic fluid enters upper accessory valve and flows
through variable output control valve HS-20 and hydraulic
quick disconnect assembly to the lower accessory valve.
Hydraulic fluid exits the valve assembly and flows through
the free-flow check valve section of counterbalance valve.
Hydraulic fluid then enters rod end of boom butt handling
cylinder, retracting the cylinder to lower the boom butt.
Fluid from piston end of cylinder is blocked by the opposite
side free-flow check valve section of counterbalance valve
and flows through the flow restraining section with a relief
setting of 3,000 psi (207 bar).
Counterbalance valve acts as a deceleration control with a
3:1 pilot ratio. Hydraulic fluid flows through boom butt
handling cylinder valve to tank through the hydraulic quick
disconnect.
When power button or boom butt cylinder switch is released,
the PC sends a 0 volt output to shift spool of solenoid HS-16
to center position.
BOOM BUTT HANDLING CYLINDER EXTEND
RF-35
AUXILIARY SYSTEM
SUCTION
MANIFOLD
RELIEF VALVE
HS-12
AUXILIARY PUMP
FAN PUMP
TO FAN
DISABLE
CIRCUIT
UPPER ACCESSORY VALVE
HS-16
HS-15
LOWER ACCESSORY VALVE
x
RF-36
AUXILIARY SYSTEM
SUCTION
MANIFOLD
RELIEF VALVE
HS-12
AUXILIARY PUMP
FAN PUMP
TO FAN
DISABLE
CIRCUIT
UPPER ACCESSORY VALVE
HS-16
HS-15
LOWER ACCESSORY VALVE
x
VARIABLE OUTPUT VALVE
0 TO 15 gpm (57 l/min)
VARIABLE OUTPUT VALVE
0 TO 15 gpm (57 l/min)
BOOM BUTT HANDLING CYLINDER RETRACT
X
X
FIGURE 1-39
(PAST PRODUCTION)
(PAST PRODUCTION)
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