Freight Trucking - Flat-bed transport and semitrailers

The importance of truck freight to the economies of North America is evident from the fact that the hundreds of thousands of miles of road and highway networks are primarily used to transport everything from raw material to the finished and semi-finished products, construction material, foods and even massive machinery at some point in the transportation and supply chain. Truck tran-sportation is so efficient and cost effective that many industrial and agricultural sectors all over the world are opting for this transportation option as the primary type over traditional rail and river/lake freight.


Semi trailers and flatbeds


These are the trailer types attached to the back of tractor units (road tractors). The tractors are high powered diesel engine heavy duty single cab vehicles with several axels. The tractor unit can couple with a trailer or any size (or commonly, multiple trailers), especially semi-trailers, and still be extremely flexible as the design is not rigid (this helps with narrow turning while pulling long semi-trailers and flatbeds). In addition to trailers, tractors also pull cranes and specially insulated and prepared tractors can pull tankers (for flammable liquids etc; the wiring and exhaust system is relocated).

Types of semitrailer-tractor trucking combinations.


Trailer van (box semitrailer) and curtain-sider: This is the most common type of semi trailer unit in use. These are the types of containers also carried on freight ships and are basically big rectangular cubes made of reinforced sheet metal. Dimensions of the various options (in terms of length) are; Standard lengths in North America; 28 ft, 32 ft, 34 ft, 36 ft, 40 ft, 45 ft, 48 ft and 53 ft. A curtain-sider is the same as a box-trailer but with removable sides made of strong, weather-proof fabric, like heavy curtains. It is easier to load and provides the protection and security of the box-trailer.
Reefer truck trailer: A reefer is a smaller box trailer capacity unit with a refrigeration unit which operates independently and cools the storage compartment. This is used to transport perishable items which need to be kept in a temperature controlled environment, such as meat, cooked and semi-cooked foods, ice-cream and medical supplies.


Bus (truck) Trailer: This is a basic bus unit which is attached to the back of the tractor to form a non-rigid bus.


Tanker and Dry bulk: as mentioned above, semi-trailer trucks can also attach insulated or common tankers for the safe and easy transportation of tankers carrying liquids such as milk or flammable liquids such as thinner or petrol. A dry bulk unit is a similar unit but used for carrying dry-items like sugar or flour.


Flatbeds: These are longer trailers, with no sides and removable rails and are used to haul objects like massive drain-pipes, girders, tree trunks, heavy machinery, vehicle (like tanks) and generally, all objects which cannot be loaded onto standard semitrailers of box containers. These are most useful to haul all objects which are heavy and can be stacked up and secured on the flat platform by strapping them down.


Other specialized types: Double-deckers, side-lifters (which self-load shipping containers) and car carrying trailers are specialized variants of semi-trailer attachments.


References:

Wikipedia

Hubpages[dot]com/hub/flatbedfreight