Manitowoc 2250 Service Maintenance Manual

Reference Only
INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-90
Published 07-19-16, Control # 249-01
Counterweight Switch
The counterweight switch is operative only in Standard or
Setup modes. It allows the counterweight strap cylinders to
be disconnected from the counterweight straps during
assembly and disassembly.
With the engine running, power is available to the MAX-ER’s
remote switch assembly when the power cable (W28) is
plugged into the receptacle on the left side of the
counterweight trailer. When the power button on MAX-ER’s
remote switch assembly is pressed, power is enabled to
operate the counterweight switch. The switch is spring-
returned to the OFF position. In the OFF position, the
counterweight strap cylinders solenoid valve is “motor
spooled” with both cylinder ports and the tank port connected
to the spool center position. This prevents premature
opening of the counterbalance valves.
Counterweight Strap Cylinders Lower
When the counterweight switch is held in the DOWN (lower)
position (extend cylinder), an input signal is sent to the PC. A
12 V output signal from the PC enables the counterweight
strap cylinder lower solenoid valve HS-41. Internal pilot
supply pressure of 14 bar (200 psi) enables the selected
spool to shift the counterweight strap cylinder solenoid valve.
The crane’s PC sends an output signal to shift the crane’s
auxiliary system disable-relief valve HS-12 to block the
valve’s bypass. Accessory system pressure increases to
operate the accessory items. Accessory system fluid enters
the MAX-ER’s accessory valve and flows through the free-
flow check valve section of the counterbalance strap cylinder
valves, entering the piston end of the strap cylinders to start
extending the cylinder rods.
Fluid from the rod end of the cylinders is blocked by the free-
flow check valve section of the counterbalance valve and
flows through the flow-restraining section that has a relief
setting of 110 bar (1,600 psi). Return hydraulic fluid then
exits the counterbalance valve and passes through the MAX-
ER’s accessory valve before returning to the crane’s
hydraulic tank through the return line. Move the release
counterweight switch to the OFF position to lock the strap
cylinders in position.
Counterweight Strap Cylinders Raise
When the counterweight switch is held in the UP (raise)
position (retract cylinder), an input signal is sent to the PC. A
12 V output signal from the PC enables the counterweight
strap cylinder raise solenoid valve HS-40. Internal pilot
supply pressure of 14 bar (200 psi) enables the selected
spool to shift the counterweight strap cylinder solenoid valve.
The crane’s PC sends an output signal to shift the crane’s
auxiliary system disable-relief valve HS-12 to block the
valve’s bypass. Accessory system pressure increases to
operate the accessory items. Accessory system fluid enters
the MAX-ER’s accessory valve and flows through the free-
flow check valve section of the counterbalance strap cylinder
valves, entering the rod end of the strap cylinders to start
retracting the cylinder rods. Fluid from the piston end of the
cylinders is not blocked by the counterbalance valve and
exits to the MAX-ER’s accessory valve before returning to
the crane’s hydraulic tank through the return line. Move the
release counterweight switch to the OFF position to lock the
strap cylinders in position.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English