3.1.3 Typical “B” type couplings – video edit draft

In this lesson:

What are the common types of B-couplings, how do they work and where are they used?

In several of the earlier parts of the course we have referred to fifth-wheel turntable couplings.

We explained that fifth-wheel couplings are used to connect prime movers and semi-trailers together.

Fifth-wheel couplings are also called B-couplings

B-couplings are used in combinations involving a prime mover and one or more semi-trailers. They may also be used in other larger combinations involving a converter dolly.

There are two parts to this coupling.


The turntable part fitted to the towing vehicle is called a fifth-wheel.


The fifth-wheel may be mounted on a prime mover, on a converter dolly or to the back of a semi-trailer.


The second part of the coupling is called a kingpin and is fitted underneath the semi-trailer.


After ensuring everything is lined up and the locking mechanism on the fifth-wheel is set, the towing vehicle is reversed under the trailer to engage the fifth-wheel and kingpin.

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