Manitowoc 2250 Service Maintenance Manual

Reference Only
Manitowoc Published 07-19-16, Control # 249-01 1-93
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 the mast accumulator pressure sender. A
pressure-relief valve opens at 207 bar (3,000 psi).
The auxiliary system’s disable-relief valve HS-12 is set at
276 bar (4,000 psi) and protects the MAX-ER systems from
excessive pressure by opening to the tank when the
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 207 bar (3,000 psi) in the
cylinders to cushion the mast.
Luffing Jib Stop Cylinders
See Figure 1-60 for the following.
Luffing jib stop cylinders on the jib strut act as hydraulic
cushions for the jib struts. The jib stop cylinder ends contact
the main jib base to prevent two-blocking between the main
strut and jib strut. After a certain distance, the jib stop
cylinders bottom out to stop the jib strut’s travel. Pressure
and return lines are routed from the accumulator at the mast
butt to the jib strut cylinders mounted at the boom top.
Jib Stop System Operation
See Figure 1-60 for the following.
After the mast stop cylinders’ system is filled, the jib strut
cylinders’ system is filled with hydraulic fluid until the
pressure is 152 bar (2,200 psi), as controlled by a pressure-
control pilot-reducing valve.
The jib strut cylinder-relief valves limit pressure to each
cylinder at 145 bar (2,100 psi). Pressurized hydraulic fluid
flows through the check valve part of the relief valves to the
piston end of the cylinders to extend the jib strut cylinders.
Hydraulic fluid from the piston end of the cylinders goes to
the vertical hydraulic tank on the jib.
The jib strut cylinders’ counterbalance vent valve is pilot
operated and opens if system pressure exceeds 165 bar
(2,400 psi).
The secondary-relief valve opens if inlet pressure to the
cylinders exceeds 179 bar (2,600 psi). Hydraulic fluid from
the primary- and secondary-relief valve goes to the vertical
hydraulic tank on the jib. Excess hydraulic fluid in the vertical
hydraulic tank is directed down the boom and returns to the
crane’s hydraulic tank.

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English