In an articulated vehicle which comprises a bogie unit (10) which is pivotally connected or pivotally connectable to a trailer chassis (12), the position of the pivotal connection (15) is displaced or displaceable relative to the neutral optimum point (22) of pivotal interconnection of the bogie unit and chassis, whereby to create a net moment at said point of pivotal connection (15) and thereby impart enhanced stability to the articulated vehicle as a whole.