Manitowoc Published 06-24-16, Control # 241-01 3-87
2250 OPERATOR MANUAL OPERATING CONTROLS AND PROCEDURES
AUXILIARY POWER UNIT (APU)
General
See Figure 3-67 for the following information.
The optional auxiliary power unit (APU) (1) is a self-
contained, stand-alone system. The APU can be equipped to
power the cab HVAC and electrical system while the crane
engine is off during downtime. The APU can also be used to
power optional lighting systems and cold weather packages.
If the crane engine and the APU engine are running at the
same time and the A/C toggle switch is activated in the cab,
the crane engine A/C compressor will shut off.
Engine
The APU is powered by a Caterpillar C1.5 diesel engine and
is equipped with a 12 V
DC
(65 A @ 3034 rpm) alternator and
an additional 28SI 12 V
DC
(160 A @ 3888 rpm) alternator.
Generator and Interlock Switch
The A/C power is supplied by a Marathon MagnaPLUS
generator located at the rear of the engine assembly. The
generator provides a continuous 120 V
AC
(10 kW @ 60 Hz)
output. The APU interlock switch (3) is protected by three
fuses rated at 60 A. There is also a rotating bed interlock
switch (11) located on the left side of the crane.
Key Switches
The APU is controlled by a three-position key switch with the
following positions: STOP (7a), RUN (7b), and START (7c).
The key switches are located either in the cab or on the APU.
The APU key switch (4) and the APU control panel (5) are
located on the APU, which is located on the left side of the
rotating bed (2).
The APU cab key switch (6) is located within the cab on the
right side control panel (8). The APU cab key switch enables
the operator to start or stop the APU as well as send the APU
status to the APU cab control panel (9). The RUN signal from
the key switch provides power to the control panel and runs
to the APU to bring it out of STANDBY mode. When the APU
engine is running, the HVAC controls (10) will function the
same as if the crane engine was running.
Safety Switches
General
Prior to performing any service, maintenance, or repairs, the
auxiliary power unit (APU) must be disconnected from its
battery source located within the APU control panel. Follow
all established and acceptable safety practices while
inspecting, servicing, or repairing the APU.
The safety systems on the auxiliary power unit (APU) should
be examined/tested whenever maintenance is performed on
the APU to ensure that they are in good condition and proper
working order.
Side Access Panel Safety Switches
It is critical that the side access panel safety switches on the
auxiliary power unit (APU) are never deactivated or
bypassed. Failure to comply may result in serious injury.
The side access panel safety switches are designed to
prevent the APU from starting when the side access panel is
loose or has been opened. When the switch is open, the
access panel has been opened or is loose. When the switch
is closed, the access panel is latched down. The switch is
located at the left side of each side access panel.
Starting with the Side Access Panel Opened
Some repair or diagnosis procedures may require the
auxiliary power unit (APU) to be started with the side access
panel opened. Never deactivate or bypass the safety cover
switch.
Starting Aids
Do not use aerosol starting aids such as ether. Use of any
starting aids can result in an explosion and personal injury
and will render the warranty null and void due to internal
engine damage.
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