What is the difference between a semi trailer and a full trailer?
Pretty simple – a full trailer is fixed to the tractor unit whereas the semi is detachable, and certainly on American roads semi trailers dominate.
Semi Trailer Advantages
The major advantage of a semi trailer is flexibility, but there are several reasons why semi trailers have this flexibility and some you may not already know:
If the tractor breaks down then another tractor can be coupled and the load continue on to destination without lengthy delay (it takes just as long as is needed to get a replacement tractor unit to the broken down units location);
A semi trailer can be attached to another semi trailer using a dolly – this is more common overseas in countries such as Australia where several trailers will be attached to form a road train;
Tugs, yard dogs or shunts can be used to shift semi trailers around loading and docking facilities – these are not full tractor units for use on the road, but they are far cheaper and easier to handle than a full tractor unit;
A semi trailer is easier to reverse than a full trailer as there is only one turning point at the coupling compared to a full trailer which has two;
A semi trailer also has a smaller turning circle compared to a full trailer;
The used semi trailer market is substantial compared to the pre-owned fixed trailer market;
Semi trailers have longer cargo beds which means they can transport longer loads;
Semi trailers generally can haul a greater load than a full trailer;
Semi trailers provide a better load ratio between tare and laden weight; and
The Bad News
Semi tractor trailers have a center of gravity which tends to be higher than full trailers which makes them prone to tipping over compared to rigid trailer construction;
Semi trailers are prone to jackknifing because they are articulated, i.e. do not have a fixed but movable attachment between tractor and trailer; and
Semi tractor units have zero use on their own.