The cargo loading system is equipped with rollertrack mounted self-lifting electrical Power Drive
Units (PDU) installed for the lateral and longitudinal movement of ULDs and controlled by a
joystick located in the doorway.
The following paragraphs provide detailed information about conveyance components, guides
and restrains, power drive and control component.
2.2.1. Conveyance components:
a) Ballmats and Ball Transfer units in entrance area:
Ballmats and ball strips are installed in the forward and aft cargo door entrance area. The ballmats and strips are equipped with ball transfer units installed in a framework, they allow multi-
SYSTEMS
entrance area of A330/A340 A. CARGO SYSTEMS
SYSTEMS
b) Roller tracks:
The roller tracks are installed in longitudinal direction, used for longitudinal transport of ULDs. The roller tracks are extruded profiles, equipped with transport rollers, endstops and XZ-latches. At certain position, the roller tracks are additionally equipped with power drive units and proximity switches below the XZ-latches allowing powered transportation of ULDs. In these roller tracks braking rollers are also installed to prevent inadvertent ULD movement.
Roller track
2.2.2. Power drive and control components:
a) Power drive units:
The Power Drive Unit (PDU) consists of an electrical motor, a gear drive and a rubber coated
roller, mounted on a rolling axle.
It is used to move the ULDs in longitudinal and lateral direction. All PDUs are activated via signal
from the control system.
It provides a towing force, sufficient to drive the ULDs in different directions. When the PDU is
switched off, the drive roller lowers automatically to its rest position, 3 mm below system height.
Roller track
Ball mat PDU, “Self - lift” type
A. CARGO SYSTEMS
b) Control components and control panel:
Loading and offloading with the lower deck cargo loading system is managed by control panels located at FWD and AFT cargo doors, that are equipped with a power ON-OFF switch to activate the CLS and a joystick to determine the direction of movement of the PDUs. On A340-500 and A340-600 aircraft an additional joystick is installed on the roof of the entrance area. From this joystick it is possible to control the all PDUs except those in the ballmat area.
In order to avoid any unexpected or dangerous ULD movement in the cargo hold some limitation systems are available : . limit switches below the XZ-latches stopping the PDU power when the ULD has reached its limit. . a switch at each door sill latch interrupting power supply for the CLS each when the latch is raised and preventing door operations when the latch is lowered.
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