B.  The floor mounted PDUs have numbers 1, 2, and 3 in the forward centerline, 4L through 7L, 17L through 19L2 in the left side, 4R through 7R,17R through 19R2, 23R, and 24 in the right side.
 C.  PDUs 2, 3, 4L(R) through 7L(R), 23R, and 24 are electrically steerable PDU. These PDUs steer automatically when control by the control panels.
 D.  PDUs 17L(R), 18L(R), 19L1(R1), and 19L2(R2), are retractable/steerable PDU. These PDUs are 90-degree steerable and also are able to retract electrically and manually.
 WARNING:  MAKE SURE THE PRESSURE OF THE WORN OUT/DEFECTIVE TIRE IS NOT MORE THAN 100 PSIG. IF THE PRESSURE OF THE WORN OUT/DEFECTIVE TIRE IS MORE THAN 100 PSIG, THE TIRE CAN EXPLODE. THE EXPLOSION CAN CAUSE INJURIES TO PERSONS OR DAMAGE RO EQUIPMENT.
 E.  Each floor mounted PDU consists of a wheel assembly driven by a rotary actuator. Some PDUs have a separate actuator for steering. Each PDU drive wheel actuator incorporates a spring-loaded brake which resists drive wheel rotation when the PDU is not operated. The brake is released magnetically when the PDU is energized.
 F.  The tray mounted system utilizes an average of three PDUs in place of a single floor mounted non-steerable PDU. These PDUs are spring loaded and remain in the raised position. Adequate vertical forces are applied by the use of the spring loads. This allows the PDU to be utilized for braking
 8.  Control Panels (Fig. 3)______________
 A.  The following cargo control panels are installed on the sidewalls of the main deck cargo compartment:
 (1) 
Master cargo control panel (M30)
 (2) 
Auxiliary cargo control panel (M5215)
 (3) 
Side door cargo control panel (M1)
 (4) 
Remote cargo control panel (M10)
 (5) 
Local cargo control panel (M20 and M262)
 (6) 
20 FT cargo control panel (M456)
 (7) 
20 FT local cargo control panels (M611 and M612)
 B.  The master cargo control panel is the main control of the main deck cargo system.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. 
A 
747-400 MAINTENANCE MANUAL 
SEEC  SEEC 
6R 7R 17R 18R5R 
23R 123 19 
4R 
4L 5L 17L6L 7L 18L 
SEE A 
RED TRIGGER 
DRIVE-WHEEL 
FLAG
SEE B 
PDU HANDLE 
DRIVE-WHEEL 
PDU ARROW 
ACTUATOR
INDICATOR 
LOCKPIN 
PDU ELECTRICAL 
CONNECTOR
DRIVE-WHEEL 
DISENGAGE DRIVE-WHEEL DISENGAGE 
CABLE SERRATED CABLE STOWAGE FITTING
INDEX BLOCK  (UNDER FLOOR)
INDEX 1 PLATE DRIVE-WHEEL ACTUATOR DRIVE-WHEEL NONSTEERABLE PDU DISENGAGE HANDLE
(FIXED AND MANUALLY ADJUSTABLE) 
PDU TORQUE REACTION
A 
FITTING (2 LOCATIONS)
STEERING 
ACTUATOR
SINGLE STUD DUMMY CONNECTOR 
(DOUBLE STUD ON AND COVER 
OTHER FITTING) (3 LOCATIONS) 
ELECTRICAL CONNECTOR LOCK BOLT 
STUD FITTING (2 LOCATIONS) ELECTRICAL 
PLUG (P1) 
WIRE BUNDLE FOR CONNECTOR 
DRIVE-WHEEL ACUATOR PLUG (P3) WIRE BUNDLE FOR ELECTRICAL 
STEERING ACTUATOR CONNECTOR PLUG (P2) FWD
ANTI-ROTATION WIRE BUNDLE FOR SUPPORT FITTING LIMIT SWITCHES (2 LOCATIONS) 
LEGEND 
RETRACTABLE/STEERABLE PDU INBD NONSTEERABLE PDU 
B 
RETRACTABLE/STEERABLE PDU 
MANUALLY ADJUSTABLE PDU ONLY 
Power Drive Units 
Figure 2 (Sheet 1)
L50235
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. 
A 
747-400 
MAINTENANCE MANUAL
POWER 
DRIVE
TRAY MOUNTED PDU
Power Drive Units 
Figure 2 (Sheet 2)
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