A 5th wheel coupling is the heavy-duty connection point fitted to a prime mover that allows it to tow a semi-trailer. It locks onto the trailer kingpin and provides a secure pivot point so the truck and trailer can turn safely while remaining connected.

In heavy vehicle applications, a 5th wheel trailer hitch and 5th wheel coupling often refer to the same type of connection system. Some customers may also refer to the assembly as a 5th wheel turntable. Our parts interpreters can help clarify the correct part terminology and supply the right component.

Choosing the right 5th wheel or turntable for your truck will depend on its use and the size of the load you are towing, and the type of maintenance you would like to perform over time. You can purchase a traditional greased turntable or the new greaseless style – which as the name indicated does not require greasing. In most applications a 2” king pin will suffice but for heavy duty applications such as road train use often a 3 ½" king pin and suitable turntable is required to suit the much heavier load being towed.  You will also need to select the pedestal height that best suits your application. If you are operating in many inner-city areas you will need a lower profile (say 150mm) pedestals for your turntable to ensure you can access tunnels and low height bridges. For rural applications many users would prefer higher pedestals that will help with clearance as another example. To select the right turntable for your application, speak to one of our parts interpreters who will be happy to assist you in finding the right 5th wheel or turntable to suit.

Yes, regular inspection and maintenance is essential. There have been many instances unfortunately where a trailer has decoupled from a prime mover due to 5th wheel or turntable failure. Clearly this can lead to catustrophic outcomes so regularly maintenance is essential.

A 5th wheel coupling should be checked for wear, correct locking operation, lubrication, mounting condition and signs of damage. Common issues are wear and tear and excess movement in the jaw, which can lead to decoupling. Jaw kits are wearable parts and are meant to be replacement regularly, so they must be inspected and replaced when excess wear is showing. Similarly king pins themselves will also wear over time through metal to metal contact, so again once excess wear presents itself ensure you replace the relatively inexpensive parts to ensure your truck and trailer remain safe.

Inspections of your 5th wheel and turntable and all associated parts must be done with a daily prestart inspection and an indepth inspection and testing measurement on tolerances completed on each regular maintenance interval.