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30-41-07
ALL ú ú 01 Page 802 ú Jun 15/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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747-400 MAINTENANCE MANUAL
WINDSHIELD WIPER SYSTEM - DESCRIPTION AND OPERATION
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General (Fig. 1)
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A. Two windshield wipers maintain a clear area on the captain's and first officer's No. 1 windows during takeoff, approach and landing in rain or snow. Each wiper is operated by a separate system to maintain clear vision through one of the windows in the event of a system failure. The windows may also be kept clear in heavy rain by using the rain repellent system (Ref 30-43-00) in conjunction with the windshield wiper.
B. Two wiper speeds may be selected. The low wiper speed is 190 |19 strokes per minute. The high wiper speed is 250 |25 strokes per minute. The wiper blades clear a 22 inch wide path through an arc of 69 degrees.
C. Each windshield wiper system consists of a drive motor/converter, a wiper arm assembly consisting of a wiper arm and a wiper blade, and a control switch located in the anti-ice-rain removal module M7321 on the P5 overhead panel. The systems are powered by 28 volts dc through circuit breakers on the P7 panel. Left system power is from the 28 volts dc bus 3 and right system power is from the 28 volts dc bus 4.
Motor-Converter Assembly
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A. The wiper arm for each system is driven by a motor-converter assembly (M17 - right, M18 - left). Each assembly is mounted on an integral access plate near its respective window. The left and right assemblies are identical except that they are mirror images of each other. Each assembly includes a motor, a converter, a cam-actuated parking switch, two relays, and a brake solenoid and brake. The converter reduces the speed of the motor and changes the rotary motion into oscillatory motor of the wiper arm.
Operation (Fig. 2)
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A. Functional Description
(1) Each windshield wiper is controlled with the WIPER control switch located in the anti-ice/rain removal module on the P5 panel.
(a)
When the LO position of the switch is selected, relay 1 in the motor is energized, which applies power to motor fields 1 and 2 in series. As the wiper leaves the park position, the internal park switch is closed. The motor operates at approximately 190 strokes per minute.
(b)
When the HI position is selected, both relays 1 and 2 are energized, which applies power to motor fields 1 and 2 in parallel. The motor operates at approximately 250 strokes per minute.
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30-42-00
ALL ú ú 01 Page 1 ú Oct 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A 747-400 MAINTENANCE MANUAL
SEE A
OFF LO OFF LO
WIPER HI WIPER HI SEE B
PILOTS' OVERHEAD PANEL WIPER BLADE ASSEMBLY
A SCREW
WASHERS
WIPED AREA
WIPER STOP
SEE C PARKED POSITION ROD BLADE RESTRAINER (WITH SPOILER)
NO. 1 WINDSHIELD, LEFT B STUD GASKET 1 LEVER WIPER ARM PRESSURE PLATE
SERRATED WASHER SCREWS
HUB WASHER
SERRATED SLEEVE SCREW
MOTOR CONVERTER
WINDSHIELD WIPER ASSEMBLY
1 MARK STUD LOCATION FOR EXACT REPLACEMENT C
Windshield Wiper System Component Location Figure 1
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
30-42-00
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