3-3
Published 11/26/2014, Control # 447-05
RT770E SERVICE MANUAL ELECTRICAL SYSTEM
Alternator
The alternator (Figure 3-2) is mounted on the engine and is
belt driven. It is a 145 ampere alternator with an integral
transformer - rectifier unit. When the engine is running, and
the alternator is turning, the alternator’s 12-volt output
terminal supplies the crane’s electrical circuits. The output
terminal also supplies the voltage to recharge the batteries
and maintain them at a full state of charge.
Batteries
The batteries (Figure 3-3) are located in a box on the left side
of the crane. The batteries are the maintenance free type
and completely sealed except for a small vent hole in the
side. The vent hole allows what small amount of gases that
are produced in the battery to escape. On some batteries, a
test indicator located on the top of the battery is used to
determine if the battery can be tested in case of a starting
problem.
A Battery Disconnect Switch is located to the right of the
battery box (Figure 3-3). To disconnect the batteries, turn the
Battery Disconnect Switch to OFF. Turn the switch to ON to
connect the batteries.
Cab Electrical Panel
NOTE: Refer to the electrical schematic in the back of this
manual for a diagram of the electrical system.
The cab electrical panel (6) (Figure 3-4) contains the cab and
superstructure relays, fuse box, wiring harness connector
bulkhead, RCL module, RCL Override switch, and the fast
pulse buzzer alarm. It is located inside the crane cab, behind
the operator’s seat. Access is gained to the back of the panel
by removing the two screws (3) (Figure 3-4) securing the
panel cover.
The two accessory relays (9, 10) (Figure 3-4) behind the cab
electrical panel control power to fuses 9 - 20 in the fuse box.
The coils of the accessory relays are energized when the
ignition switch is at the RUN or ACC position.
The fuse box (2) (Figure 3-4) in the cab electrical panel
contains twenty fuses. Fuses 1 through 5 are energized
when the battery is connected. When the battery is
connected and the Ignition Switch is at the RUN position,
fuses 6 through 8 are energized. If the Ignition Switch is at
the ACC position, fuse 8 will be energized while fuses 6 and
7 remain de-energized. Fuses 9 through 12 are energized
through ACC relay # 1 and 13 through 20 are energized
through ACC Relay#2.
NOTE: The cab control modules and RCL module are not
serviceable; contact Crane Care Customer Service
with any service or repair questions about the
modules.
FIGURE 3-2
7874
Alternator Belt
Alternator
FIGURE 3-3
7858
Batteries Battery Disconnect Switch
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