SYSTEMS
A. CARGO SYSTEMS
SYSTEMS
2.2.3. Guides and restraints:
a) Door sill:
Door sill latch units are installed in the FWD and AFT cargo door areas. Each door sill latch
consists of: . a YZ-latch, which allows to latch the ULDs positioned in the door entrance area. . an overrideable Y-latch which prevents inadvertent roll out of ULDs during
loading and off-loading. . a guide roller which is used to transfer of ULDs between the loader and the ballmat area.
The YZ-latch is operated manually. It can be lowered by pressing a red lever at the side of the unit and can be raised by being pulled up by hand. Each lever of the door sill latch units is electrically monitored by a limit switch to ensure that the cargo door cannot be closed when the YZ-latch is in its lower position and that the CLS is not powered closed when the YZ-latch is in its up position.
The overrideable Y-latches are spring loaded and operated automatically or manually. They are overrideable in loading direction, returning to the raised position once the ULD has passed over, to prevent inadvertent roll out. Before ULD offloading, the Y-latch has to be lowered manually by means of a handle located on the cargo loading system control panel. When the handle is pushed down, a hydraulic damper delays the Y-latch raising to allow ULD unloading.
A. CARGO SYSTEMS
b) Entrance guides:
The door entrance guides provide a correct guidance on the ballmat during loading or offloading
of ULDs and prevent impact to the doorframe.
Entrance guides system is made of guides acting in different directions : . a mechanical Z-guide is installed for guidance of ULD baseplates under the endstops.
. a spring loaded Y-guide is installed with a guide roller, which provides sufficient clearance between ULD‘s baseplate and the door frame during loading and offloading.
. retractable Y-guides prevent the ULD‘s from turning while entering the compartment. To transport the ULDs to their final position those guides have to
Entrance guides AFT door Entrance guides FWD door Y-guides
c) Fixed YZ-latches and side guides opposite of cargo door:
The fixed YZ-latches serve to guide in X-direction and to lock ULDs in Y-and Z-direction. These latches are located at each frame on both sides of the cargo compartments. A vertical guide roller is installed in the YZ-latch. Each YZ-latch is equipped with a tie-down point, designed to a maximum load of 2000 lbs (890daN) or 4000 lbs for A340-500 and A340-600 in any direction. Additional side guides are basically installed opposite of each cargo door to align ULDs and optional continuous side guides are installed all along the cargo holds.
Fixed YZ-latch
SYSTEMS
A. CARGO SYSTEMS
SYSTEMS
d) Overrideable YZ-latches (A310, A300, A330, A340):
Overrideable YZ-latches, also known as —butterfly“, are provided to lock half-size containers in Y-and Z-direction. These latches are attached to the structure at aircraft centerline. During loading of full size containers the latches are overridden. The two latch claws are spring loaded so they raise again when the ULD has moved on.
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本文链接地址：Getting to Grips with Aircraft Weight and Balance(15)
