A. el Hadrati
Automatische laad-lossystemen van stukgoederen in/uit vrachtwagens.
Report 2003.TL.6826, Transport Engineering and Logistics.
In the last years, several systems have been developed for automatic
loading and unloading of palletized and non-palletized goods in trailers.
These systems can be categorized in:
With the use of automatic systems a very short time is needed to load or
unload a trailer. In just 5 minutes a long trailer of 13,6 meters can be
completely loaded. Disadvantages of automation of loading systems are the
required systems in the trailers and less flexibility in the
loading/unloading process by automated stationary docks.
- Chain conveyor systems and roller conveyor systems:
These are systems with roller conveyors, chain conveyors or combinations
of both. The conveyors are built in the trailer and are used to move load
units such as pallets. Air-cargo pallets can also be loaded with
non-powered roller conveyors combined with special drive units.
These systems can be used in two different ways: stand-alone or with a
stationary dock system. With driven conveyors the dock system moves the
complete cargo load, fully automatic into the trailer.
- Moving floor systems:
like the chain conveyors and roller conveyors, moving floor systems are
built stationary in the warehouse and in the trailer, or only in the
trailer for stand-alone use. Examples of such systems are megabelt systems,
slat systems and walking floor systems. Driven belts and slats move the
total load in or out of the trailer. The flat floor in this
systems provides flexibility in loading different load units.
Walking floor systems are specially designed to load or unload bulk
materials, but they can also be used for loading or unloading of pallets.
- Skate systems:
very long dock driven elevated skates pick up a pre-assembled load and put
it into the trailer in one shot. There is no special system in the trailer
required. Such systems can be used to load and unload standard pallets and
in some cases also roll containers.
- Loading/unloading robots:
Like unmanned fork-lift trucks, loading robots are designed to
automatically pick up pallets and drive it into the trailer. Using
advanced sensor technology and navigation technology the robots can feel,
measure the internal dimensions of the trailer and put the pallets in the
specified place. The robots are computer controlled and are mostly
integrated in a total internal transport system.
- Various other systems:
crane systems and automated telescopic conveyors can also be used for
automatic loading and unloading. Cranes, equipped with forks, can pick up
two or four pallets at a time and put them onto the trailer. The cranes
automatically receive pallets from a stationary system connected to the
stack in the warehouse.
Automatic telescopic conveyors can extend into the trailer and load sacks
without the need of an operator. An intelligent computer sensing system
controls the machine as it moves automatically inside the vehicle
depositing loose parcels from the floor to the roof.
Especially for loading boxes and cases in trailers, automatic stacking
systems are designed. Such systems load and stack packages automatically
by adjusting its position by sensing the sidewalls as it load and back up.
The boxes are fed from the warehouse with telescopic conveyors.
Loading systems whereby trailers must be modified, are only efficient in
cases of shuttle transport and short cyclic transportation, e.g. between the
production and a nearby situated warehouse.
Loading robots are more flexible in the loading and unloading process and
require no equipment in the trailers. Therefore the robots are expected to
be more frequently used systems in the future.
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