Low loader trailer is a name used for trailers with a main deck height lower than the height of the trailer’s rear wheels. The deck of a low loader trailer has two steps in it: one from the upper deck above the tractor unit’s fifth wheel, and one from the rear deck above the trailer’s wheels.
A low loader trailer may have a very low deck height; as low as 230mm in the case of a Doll trailer with detachable neck. More typical heights are 600mm for a four axle low loader trailer, and 300mm for three axle low loader trailer. The later may carry a 40 Tonne payload.
Low loaders tend to be built with twin beams and removable floor sections, to enable loads to sit between the beams.
Where the burden of a low loader trailer can be craned onto the trailer no practical problem is presented by the higher deck section over the rear wheels of the trailer. However, self-propelled machines cannot be driven onto the trailer, as they could be onto a flat or step frame trailer, using ramps. To overcome this problem, some low loader trailers are built with a detachable neck. The upper deck and neck of the low loader trailer can be unpinned and disconnected from the body of the trailer, driven away on the fifth wheel of the tractor unit. Self-propelled machines, such as road graders, combine harvesters, or cranes, can then be driven directly onto the lower deck of the low loader trailer.
A low loader trailer may or may not have the ability to extend in length.