Manitowoc 2250 Service And Maintenance Manual

Reference Only
Manitowoc Published 11-06-15, Control # 040-13 1-97
2250 SERVICE/MAINTENANCE MANUAL INTRODUCTION
1
After the accumulator is filled, the mast stop cylinders and jib
strut cylinders are filled with pressurized hydraulic fluid,
monitored by mast accumulator pressure sender. A pressure
relief valve opens at 3,000 psi (207 bar).
Past units have an unloader valve that cuts in at 2,300 psi
(159 bar) and cuts out at 2,900 psi (200 bar).
Auxiliary system disable valve is set at 3,500 psi (241 bar)
and protects the MAX-ER systems from excessive pressure
by opening to tank when accessory items are disabled.
Each mast stop cylinder has a counterbalance valve at the
cylinder piston end port. These valves hold hydraulic
pressure at approximately 3,000 psi (207 bar) in cylinders to
cushion mast.
Jib Stop Cylinders
See Figure 1-61 for the following procedure.
Luffing jib stop cylinders on jib strut act as hydraulic cushions
for jib struts. Jib stop cylinder ends contact the main jib base
to prevent two-blocking between main strut and jib strut.
After a certain distance, the jib stop cylinders bottom out to
stop jib strut travel. Pressure and return lines are routed from
the accumulator at mast butt to jib strut cylinders mounted at
boom top.
Jib Stop System Operation
See Figure 1-61 for the following procedure.
After mast stop cylinders system is filled, the jib strut
cylinders system is filled with hydraulic fluid until the
pressure is 2,200 psi (152 bar) as controlled by a pressure
control pilot reducing valve.
Jib strut cylinder relief valves limit pressure to each cylinder
at 2,100 psi (145 bar). Pressurized hydraulic fluid is through
check valve part of relief valves to piston end of cylinders to
extend jib strut cylinders. Hydraulic fluid from piston end of
cylinders goes to vertical hydraulic tank on jib.
The jib strut cylinders counterbalance vent valve is pilot
operated and opens if system pressure exceeds 2,400 psi
(165 bar).
The secondary relief valve opens if inlet pressure to
cylinders exceed 2,600 psi (179 bar). Hydraulic fluid from
primary and secondary relief valve goes to vertical hydraulic
tank on jib. Excess hydraulic fluid in vertical hydraulic tank is
directed down boom and returns to crane hydraulic tank.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English