Handling Behavior of Racing Karts

A theoretical analysis of the cornering behaviour of vehicles with locked differential is presented in this paper. In particular, attention is focused on karts, which, being characterised by the lack of any differential and suspension system, show a peculiar dynamic behaviour. A linear model for cornering dynamics is obtained in the first part of the paper: the yaw equilibrium is affected by the absence of the differential, since the longitudinal forces acting on the rear tyres are no longer equal. The steady state behaviour and the handling stability are then investigated using the developed model and discussed in comparison with those of an ordinary vehicle. The understeer gradient is shown to be a function of a steering parameter, such as, for example, the longitudinal speed, in addition to the lateral acceleration; as a consequence, the handling diagram is dependent on the manoeuvres used to obtain it. Even if obtained by means of a simple linear model, these results can give some indications for racing vehicles, such as formula cars, whose differential is frequently completely or partially locked.