Manitowoc 2250 Service And Maintenance Manual

Reference Only
INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-84
Published 11-06-15, Control # 040-13
Counterweight Jack Cylinders
See Figure 1-52 and Figure 1-53 for the flowing procedure.
There are four counterweight jacks: one front left jack, one
front right jack, and two rear center jacks. The counterweight
trailer jack system is for raising wheels off ground to move
steering arms to desired steering position. The jacks allow
the counterweight trailer to stand by itself when not attached
to crane and to aid in tire maintenance. Axle wedges help
stabilize the counterweight trailer when it is not attached to
the crane and the jacks are retracted.
Each jack cylinder has a counterbalance valve at each
cylinder port. These valves allow smooth operation when
using jack cylinders. Counterbalance valves lock cylinders in
position if there is a problem with the system.
Counterbalance valves also provide relief protection for the
cylinders.
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 jack switches.
The four switches are spring-returned to OFF position.
Jack Cylinder(s) Extend
When selected left, right, center, or extend all switch is held
in the UP extend position, an input signal is sent to the PC. A
12-volt output signal from PC enables the jack cylinder
extend solenoid HS-44, HS-46, and/or HS-48. Internal pilot
supply pressure of 200 psi (14 bar) enables spool to shift the
selected jack cylinder solenoid valve(s). Internal relief valve
and shuttle valve for each spool valve allows pressure to be
divided equally when more than one valve is operated at a
time. 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 to free-flow check valve section of
counterbalance valve. Fluid pressure on piston end of
selected jack cylinder extends jack cylinder to raise the
counterweight trailer.
Fluid from rod end of jack 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
4,000 psi (276 bar). Rod end cylinder pressure opens
restraining section of counterbalance valve, allowing fluid to
exit valve. Return hydraulic fluid passes through MAX-ER
accessory valve before returning to crane hydraulic tank
through return line.
When desired jack cylinder extension is reached, release
selected jack switch to OFF to lock jack cylinder(s) in
position. Hydraulic fluid at piston end of jack cylinder
counterbalance valve supports the weight and gravity force
of the wheeled counterweight trailer.
DANGER
Tipping Hazard!
Wheeled counterweight assembly can tip:
• Extend and retract jack cylinders slowly to maintain
counterweight trailer as level as possible.
• Do not extend jacks if counterweight trailer is not
attached to crane and wheels are not at 90 degrees
(stand alone position).
• Make sure counterweight tray pins are in proper
position when raising counterweight trailer with jacks.
• Read and understand counterweight trailer jack
procedure before operating MAX-ER remote switch.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English