INTRODUCTION 2250 SERVICE/MAINTENANCE MANUAL
1-72
Published 07-19-16, Control # 249-01
MAX-ER Accessory Valve
See Figure 1-45 for the following.
The MAX-ER’s accessory valve manifold is mounted on the
wheeled counterweight trailer. A relief valve limits the MAX-
ER’s accessory valve pressure to 207 bar (3,000 psi).
The auxiliary system’s disable valve 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.
The MAX-ER’s accessory valve manifold contains eight four-
way, three-position spool valve sections. Six of these
sections are open-centered and motor-spooled, and two
sections are closed-centered. Each spool section is
electrically enabled (12 V) with switches and/or the PC. Each
valve is actuated by an internal 14 bar (200 psi) pilot supply,
filtered with a 40-micron filter. The system pressure of each
valve section is controlled independently by a relief valve,
preset to 207 bar (3,000 psi), in the inlet section permitting
more than one valve section to operate at the same time and
at different operating pressures. When the operating
pressure of a valve section is 207 bar (3,000 psi), the
sequence valve closes the inlet port to pump flow. System
pressure is limited by a pressure-relief valve in the inlet
section through the section’s shuttle valve. Both cylinder
ports on each valve section have flow limiter valves that are
preset for a predetermined flow rate.
MAX-ER Pressurized Air Supply
Pressurized air from the crane’s engine compressor provides
air to operate the mast backhitch pin cylinders, drum 2 pawl,
mast stop-raising cylinders, and boom stop-cushion
cylinders.
Each air solenoid valve is assigned an AS number. The AS
number identifies each air solenoid valve.
Table 1-5. Air Solenoid (AS) Valves
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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