INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-76
Published 11-06-15, Control # 040-13
MAX-ER Accessory Valve
See Figure 1-46 for the following procedure.
The current MAX-ER accessory valve manifold is mounted
on the wheeled counterweight trailer. A relief valve limits
MAX-ER accessory valve pressure to 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.
MAX-ER accessory valve manifold contains eight four-way
three position spool valve sections. Six of these sections are
open centered motor spooled and two sections are closed
centered. Each spool section is electrically enabled (12 volts
DC) with switches and/or the PC. Each valve is actuated by
an internal 200 psi (14 bar) pilot supply, filtered with a 40-
micron filter. The system pressure of each valve section is
controlled independently by a relief valve, preset to 3,000 psi
(207 bar), in the inlet section permitting more than one valve
section to operate at the same time and at different operating
pressure. When the operating pressure of a valve section is
3,000 psi (207 bar), the sequence valve closes inlet port to
pump flow. System pressure is limited by pressure relief
valve in the inlet section through the section shuttle valve.
Both cylinder ports on each valve section have flow limiter
valves that are preset for predetermined flow rate.
MAX-ER Pressurized Air Supply
Pressurized air from crane’s engine compressor provides air
to operate mast back hitch pin cylinders, drum 2 pawl, mast
stop raising cylinders, and boom stop cushion cylinders.
Each air solenoid valve in this section is assigned an AS
number. The AS number identifies each air solenoid valve.
AS-1 Mast Backhitch Pins Cylinder Extend (N/C)
AS-2 Mast Backhitch Pins Cylinder Retract (N/O)
AS-21 Drum 9 Pawl In
AS-22 Drum 9 Pawl Out
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