5
1
2
4
3
6
8
7
9
10
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1. Wiper arm
3. Pivot cover
5. Wiper blade
7. Motor
9. Circuit breaker
2. Wiper arm nut
4. Mounting bracket
6. Linkage
8. Pivot
10. Wiper switch
Figure 6-91.--Electrically operated windshield wipers.
Whether or not the directional signal switch
Electrical windshield wipers (fig. 6-91) are usually
driven by shunt or compound wound motors. The
lever has returned to the neutral position after
wipers may be driven in three different speeds--slow,
completion of a turn.
medium, and fast.
Whether the system is operating properly or
To obtain satisfactory operation from electrical
improperly.
windshield wipers, it is essential that the motor,
When the signal switch lever is moved in one
linkage, and drive pivots operate freely. Otherwise
direction or the other, a circuit is completed between
operation may be noisy or complete failure may result.
the battery and the proper indicating lights. The
A modern three-speed windshield wiper schematic
connections are completed through a flasher, a device
is shown in figure 6-92. The system contains a
that opens and closes the circuit at proper intervals,
providing a flashing signal. The flashing action is a
result of heating a thermostatic element within the
MOTOR
SERIES
flasher. The wiring circuit of a representative
FIELD
stop-directional light signal system indicating a right
SHUNT
turn with the brakes applied is shown in figure 6-90.
FIELD
M
WINDSHIELD WIPERS
CIRCUIT
BREAKER
Windshield wipers usually consist of a metal strip
with a rubber insert attached to a rod that swings in an
R2
LO
M
R1
arc across the windshield. The necessary mechanical
linkage is driven by an electric motor. Windshield
HI
OFF
wipers are not a common support equipment accessory.
LO
M
However, they must be installed when the operator is
OFF
HI
situated in an enclosure. Examples are the crash cranes,
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some types of fire trucks, and enclosure-equipped tow
Figure 6-92.--Schematic diagram of a three-speed windshield
tractors.
wiper.
6-73
