Manitowoc Published 11-06-15, Control # 040-13 1-79
2250 SERVICE/MAINTENANCE MANUAL INTRODUCTION
MAX-ER Modes
In Setup mode, the PC operates the same as in Standard
mode, but boom-up limit is bypassed.
In Luffing Jib mode, drum 5 cannot operate unless drum 4 is
parked. In Standard mode, drum 4 can not operate unless
drum 5 is parked.
In MAX-ER mode, the PC responds to load changes by
raising or lowering the wheeled counterweight assembly.
The PC applies drum 9 brakes, controls crawler travel pump
speed, and selects control handle operation depending on
crane mode version. See Operating Controls in Section 3 of
the MAX-ER Operator Manual for MAX-ER operation.
Electrical System
An electrical cable (W27) from MAX-ER programmable
controller on crane to MAX-ER junction box on wheeled
counterweight trailer provides electrical wiring to MAX-ER
components.
MAX-ER electrical components include:
• Strap cylinders limit switch
• Strap cylinders pressure senders
• Counterweight tilt sensor
• MAX-ER accessory valve solenoids
• MAX-ER remote switch assembly
Other MAX-ER electrical components mounted on crane
include:
• Load pin sensor
• Mast back hitch pin cylinders
• Rear or right rear drum pawl
• Rear or right rear drum pawl limit switch
• Drum 9, crawler travel, and boom hoist diverting valves
• Mast angle limit
• Boom angle indicator
• Maximum boom angle limit switch
• Mast back hitch pins remote switch assembly
Other MAX-ER electrical components for drum 9 mounted on
boom butt include:
• Left/right motor controls
• Flange speed sender
• Minimum bail limit switch
• Drum pawl
• Drum brakes
MAX-ER Remote Switch Assembly
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. Counterweight
raise/lower switch is only active in Setup mode. All other
switches can be operated in any crane-operating mode.
When power button on MAX-ER remote is pressed, power is
enabled to operate MAX-ER cylinders.
When a MAX-ER remote switch is enabled an input signal to
the PC. The crane PC sends an output signal to shift crane
auxiliary system disable valve HS-12, to block valve bypass.
This increases current MAX-ER accessory pressure to
3,000 psi (207 bar) to operate MAX-ER cylinders.
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.
Mast Back Hitch Pins Remote Switch
Power is available to mast back hitch pins remote switch
when power cable (W29) is plugged into receptacle at
bottom main junction box at left side of crane and engine is
running.
When power button and retract buttons are pressed, the
back hitch cylinders retract the mast back hitch pins. When
power button and retract buttons are released, the back hitch
cylinders, with spring assist, extend the mast back hitch pins.
Digital Display
Scroll to CTWT BHITCH screen of digital display to observe
counterweight position. CTWT indicates up or down position
of wheeled counterweight assembly. BHITCH indicates back
hitch loading in U.S. tons.
MAX-ER (MXR) diagnostic screen displays PC monitored
operating conditions. System messages are shown in Tables
1, 2, and 3 of the Digital Display Readings topic in Section
10.
Pressure Senders and Speed Senders
See Figure 1-48 for the following procedure.
A counterweight strap cylinder pressure sender is located at
the rod end of each strap cylinder and the piston end of right
side strap cylinder. The counterweight strap cylinder
pressure senders measure system pressures and send the
information as input voltages to the PC.
Drum 9 flange mounted speed sender (encoder) detects
speed and direction of drum movement. The PC receives
this information as two out-of-phase square wave voltages
that are converted to “counts”. The PC then determines
when to apply the brake or adjust pump flow.
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