'Trailer swing' is the name given to the condition of an articulated vehicle when its trailer wheels are locked and hence the trailer does not necessarily follow the tractor unit but tends to swing out during cornering. It differs from jack-knifing in that trailer swing is shown to be a quasisteady phenomenon for which there is a particular angle of swing for steady conditions of lateral and forward acceleration or deceleration of the unit. The work reported upon consists of measurements of the angle of trailer swing for known conditions or manoeuvres of an articulated vehicle. Predictions of these angles are based on a formula derived from a theoretical representation and good agreement is obtained. The formula shows that the angle of trailer swing may reach 90 degrees or more and shows how it is related to speed, lateral and longitudinal accelerations, trailer tyre sliding friction and the geometric layout of the trailer and its load. The practical implications and possible means of preventing trailer swing are discussed. (Author/publisher)
Abstract