Theoretical Investigation of the Driving Response of Articulated Buses 845096
The directional dynamics of various types of articulated bus concepts is compared upon calculation based simulation. The yaw stability is investigated under conditions of straight run. The vehicle running at constant speed is brought to snaking by means of steer impulse. The steer impulse simulates a lane change manouevre. The pusher articulated buses are more prone to yaw oscillations after a disturbance than the rear-engine articulated buses with middle axle drive and the conventional articulated ones. The main reason of the lower stability behaviour of pusher aticulated buses is caused by the mass centre of the rear section being near the rear section axle. Shifting the articulated joint backward without changing the dimensions affects favourably the space requirement during off-tracking, however, the stability performance gets worse. Shifting the rear section axle backward improves the stability performance of all articulated bus concepts, while allowing to extend their overall length up to the admissible margin of 18 m. The distance between the articulated joint and the rear section axle should be as great as possible. The stability limit of empty pusher articulated buses is lower than that of loaded ones. The state of loading does not appear to affect other types of articulated buses. The stability behaviour of pusher articulated buses may be improved through hydraulic damping between the front and rear section. The articulated damping appears to depend both from the running speed of the vehicle and of the state of its loading.