Overhung Hitches - updated March 2019

When a side force hits a trailer attached by a hitch that is NOT overhung (top), there is NO consequential side force on the tow vehicle. When a side force affects a trailer with an overhung hitch (bottom), the resultant side forces on the tow vehicle are material
When a side force hits a trailer attached by a hitch that is NOT overhung (top), there is NO consequential side force on the tow vehicle. When a side force affects a trailer with an overhung hitch (bottom), the resultant side forces on the tow vehicle are material

All conventional caravans and camper trailers are towed via an overhung hitch attached to the extreme rear of the tow vehicle.

This overhung hitch transfers the necessary nose weight of the caravan to the rear of that tow vehicle. It is also subject to forces due to the caravan yawing (swaying sideways). As the caravan yaws clockwise, that overhung hitch pushes the tow vehicle anticlockwise - and vice versa. This induces in inherent instability. The greater that overhang, the worse the effect. It is undesirable at low levels and dangerous at high levels. 

Physicists call this the Double Pendulum effect that can result in a 'chaotic' jack-knife and often rollover 'fuelled' by the rig's critical momentum.

We want the tow vehicle to be manipulated only via its steering wheel, but the overhung hitch can literally force the tow vehicle out of line from its rear end - and overwhelming the rig.

Never use a tow hitch that extends that overhang (often to ease coupling and uncoupling). Safety is  more important. 

Overhung hitches used for caravans and camper trailers because a typical tow vehicle is used also for other than towing. (It has been done, but having a permanent tow hitch inside the rear luggage compartment of a tow vehicle is not practical for everyday use.

The adverse effects of an overhung hitch can be reduced, but never eliminated.

 A full explanation is in our Why Caravans Rollover - and how to prevent it . This book explains just why rollovers happen. It enables you to estimate the stability of your own rig - and how to improve its stability. Good value for $19.95!



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