Driver Knowledge Tests

How do you connect a truck and dog trailer?

There are two main types of trailer coupling used in Australia: a semitrailer which uses a turntable (or fifth wheel) and a truck and trailer which uses bolt coupling device and drawbar with a towing eye.

The three most common brands for bolt coupling devices are:

  • Ringfeder
  • V. Orlandi
  • Rockinger

The type of unit is often generically called a Ringfeder, even though that’s one of the brands.

A Ringfeder bolt coupling (A) connected to a drawbeam (B) with jackknife sensors (C). D is the release handle, E is the locking pin and F are the connections for the air lines and electrics. The bolt is shown in the middle of the coupling, above A.
A drawbar (A) with towing eye (B) and the air and electric lines (C)

The towing eye enters the mouth of the coupling, and the bolt drops through it. Jackknife sensors are not a standard piece of equipment, but if the driver jackknifes the trailer too far, it will bend the towing eye or the drawbar.

Bent towing eye

To couple the truck to the trailer, the driver ensures the bolt in the coupling is up. The driver reverses the truck until the towing eye enters the mouth of the coupling and hits the back of the coupling. Depending on the unit, the bolt might drop through the towing eye, or the driver may need to get out and do it. The driver then checks that the bolt is through properly and that the locking pin has snapped closed.

The coupling can be damaged by reversing in too quickly, or if the drawbar is too high or low.

Once the trailer is coupled, the air and electrical lines are connected (and hydraulics if it’s a tipper truck). A tug test is performed, then the driver is ready to go.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

Tagged with:
Posted in Advice