ABSTRACT
The economics of railways in which expensive infrastructure is justified by large traffic flows requires the operation of either many vehicles with short headways or very large vehicles to provide the required capacity. Hence the concept of the train. In many cases the interaction between the vehicles in a train is minimised by the form of coupling between the vehicles, so that longitudinal forces can be transmitted between car bodies, but the coupler is capable of transmitting little or no lateral force or yaw couple. In this case it is a good approximation to treat each vehicle as if it were isolated and the lateral dynamics of each vehicle can be considered to be largely independent of that of the rest of the train. However, the need to improve curving performance, maximise the use of the clearance gauge, minimise axle loads, reduce mass, aerodynamic drag and cost has led to many designs in which there is articulation of the car bodies of a vehicle or train, so that the connections between vehicles form an essential part of the running gear. In this Chapter articulated vehicles, in which the relative motion between the car bodies is used to influence the stability and guidance of the vehicle, are considered.
