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MAINTENANCE MANUAL
FORWARD COMPARTMENT CARGO CONTROL PANEL AFT COMPARTMENT CARGO CONTROL PANEL
FORWARD COMPARTMENT POWER DISCONNECT PANEL AFT COMPARTMENT POWER DISCONNECT PANEL
Containerized Cargo Handling System Control Panels
Figure 2
L46342
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MAINTENANCE MANUAL
9. Operation
_________
A. Functional Description
(1)
General
(a) The cargo handling system may be used to handle containers, pallets or special cargo. To set the system when changing from one type of package to another, it is only necessary to reposition the lateral guides switch and to operate the appropriate restraints (AMM 25-54-00/001, Containerized Cargo Restraining System). The system controls are operated by 28-volt dc power; the power drive unit motors and the extension/retraction actuator motors are operated by 115/200-volt, 400-Hz, 3-phase power. All power for the system is taken from the ground handling buses located on the P714 panel. The dc power for the controls is routed from the ground handling bus on the P414 panel through the unlocked and up contacts of the cargo door interlock switches, which prevent powered system operation unless the door is fully open.
(2)
Special Tools and Equipment
(a) 3PRE65B00040 - Lower Cargo Door Opening Safety Barrier
(3)
References
(a)
AMM 24-22-00/201, Manual Control - Maintenance Practices
(b)
AMM 52-34-00/001, Forward/Aft Cargo Doors - Description and Operation
(c)
The system is prepared for operation by placing the power drive switch on the control panel to ON in the aft compartment, or to FWD or AFT DRIVES in the forward compartment. The switch directs 28-volt dc power to the joystick and the lateral guides switch.
(d)
Cargo movement is commanded by positioning the joystick, which is spring-loaded to neutral, to any of the eight operating positions. Joystick selection applies 28-volt dc power to a phase reversing relay and the power drive unit motor relays located in the P86 panel (forward compartment) or P59 panel (aft compartment).
(e)
The position of the lateral guides switch determines the extend/retract action of the lateral guides. With the switch positioned to NORMAL, the guides extend, or remain extended When the joystick is selected to IN or OUT; the guides retract, then extend again after a short time delay. When the joystick is selected to any other operate position. The switching action of a 1.5-second time delay relay causes the cycling action. With the switch positioned to RETRACT FWD or RETRACT BOTH. The selected guide rails remain retracted in all joystick positions.
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747-400 MAINTENANCE MANUAL
(f) The drive wheels in bays 4, 5, 6 and 7 are controlled by selecting the bay cutoff switches to ON or OFF. With the switches off, the ac power is isolated from the power drive units.
B. Control
(1) Turn System On
(a)
Provide electrical ground power (AMM 24-22-00/201).
(b)
Open cargo compartment door (AMM 52-34-00/001).
WARNING: TAKE CARE WHEN WORKING IN THE VICINITY OF OPEN DOORWAYS.
_______ INSTALL LOWER CARGO DOOR OPENING SAFETY BARRIER 3PRE65B00040 AS NECESSARY TO PREVENT FALLS.
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