Dynamic Behaviour of a Tractor–trailer Combination during Braking

Both the theoretical and practical aspects of braking in a tractor and single axle trailer combination were examined using appropriate tests that also measured other behavioural characteristics of the combination. The results showed that braking distance or deceleration can be calculated accurately but the actual braking behaviour on icy roads can currently be determined only by testing. The results also showed that the test standards for agricultural trailer brakes can give erroneous results when single axle trailers are used. Future standardisation work in single axle trailers should employ modified test procedures. In standards and legislation, braking performance is often determined by the stopping distance or deceleration value. For brake performance the braking ratio can be calculated from the axle load and deceleration. This value gives a better figure for the torque capacity of the trailer brakes and in brake performance tests should be used instead of stopping distance or deceleration values.