General
Powered drive units (PDUs) move containers and pallets.
There are two types of PDUs:
*
Lateral
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Longitudinal.
Lateral PDU
There are six lateral PDUs in the forward cargo compartment. Three lateral PDUs are in the aft cargo compartment. The lateral PDUs move containers and pallets into or out of the cargo compartment.
longitudinal PDU
There are 28 longitudinal PDUs in the forward cargo compartment and 20 in the aft cargo compartment. They move containers and pallets forward or aft in the compartment.
Location
Lateral PDUs are in the ball panel area, bays B and C forward compartment, bays E and F aft compartment (not shown).
Longitudinal PDUs are throughout the compartments.
Training Information Point
The lateral PDUs are interchangeable with the longitudinal PDUs.
You identify individual PDUs by PDU row location number and its location in the row, right, center or left. For one example, 5R is the PDU in the fifth row of PDUs from the front of the compartment on the right side. For another example, 4C in the forward compartment is the center PDU in the fourth row from the front of the compartment.
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CARGO HANDLING SYSTEM -POWERED DRIVE UNIT -INTRODUCTION
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CARGO HANDLING SYSTEM -POWERED DRIVE UNIT -FUNCTIONAL DESCRIPTION
General
The power drive unit (PDU) has these parts:
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Hinge
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Actuator
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Roller guards
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Rollers
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Mounting base
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Electrical connector
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Lift cams.
The actuator attaches to the mounting base at the hinge. The rollers are a hard rubber-like material. The lift cams are on the bottom side of the actuator.
Functional Description
The PDUs actuator has a reversible AC motor (not shown) that drives the rollers and lift cams through reduction gears (not shown). The actuator also has an internal erection coil (not shown) that locks the lift cams when the PDU is in the raised position. The motor has an electrically activated brake (not shown). It stops and holds the motor when the PDU is not in the drive condition. The lift cams move the PDU up the first time the motor is in the drive condition. The cams keep the PDU up until power is removed from the PDU. Power to the PDU is removed by any of these:
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System power switch
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Bay OFF switch
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Cargo system controller (CSC) control logic.
Training Information Point
When you replace a PDU you must clean and seal the PDU mounting base to the airframe. Then make sure electrical resistance between the PDU and airframe is acceptable. Make sure the wire bundle is clamped (not shown) to prevent fraying.
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CARGO HANDLING SYSTEM -POWERED DRIVE UNIT -FUNCTIONAL DESCRIPTION
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CARGO HANDLING SYSTEM -SILL ROLLER
Purpose Training Information Point
The sill rollers support cargo as it moves through the cargo The roller is a LRU.
door opening. The rollers make sure that the cargo is at same
height of the balls in the ball panels. They also give a place to
tie down cargo.
Physical Description
There are two types of sill rollers:
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Non-Cantilevered
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Cantilevered.
The forward cargo handling system uses both types. The aft system uses only the cantilevered type.
The sill rollers have these parts:
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Anchor fitting
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Roller
*
Bracket.
Location
There are five sill rollers in the forward cargo compartment on the cargo door sill. The first and last sill rollers on the forward cargo door sill are the non-cantilevered type. There are three sill rollers in the aft cargo compartment on the cargo door sill. All three are cantilevered.
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777 AIRCRAFT MAINTENANCE MANUAL
CARGO HANDLING SYSTEM -SILL ROLLER
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CARGO HANDLING SYSTEM -GUIDE ROLLERS
Purpose
The guide rollers guide and align cargo as it moves through the cargo door opening.
Physical Description
The guide roller has a bracket and a roller. The guide rollers in the forward cargo compartment have a different bracket than the ones used in the aft cargo compartment. The side guide rail attaches to the bracket of the guide rollers.
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