Role of Body Roll in Caravan Fishtailing

Abstract

During towing of a caravan or trailer it is not uncommon that the trailer sways back and forth as a result of steering input, crosswind or one of many other causes. Normally there is sufficient damping in the oscillations to realign the trailer with the tow vehicle. On some occasions the swaying enters an uncontrollable phase where the sway amplitude increases at each cycle. This paper examines the contribution of body roll of caravans to the out-of-control sway. The paper proposes resonance of fundamental body roll frequency with the sway frequency as a significant contributing factor. It also proposes that body roll can control sway amplitude helping to explain the out-of-control condition. There are some keys offered that may interest caravan manufacturers and caravan owners alike.