Abstract: A twin-axle rail-bogie which incorporates a steering mechanism for positively steering one or both of the axles of the rail-bogie in proportion to the rotation of the frame of a structure supported by this rail-bogie. Steering is achieved by slidably mounting one of the axle end supporting assemblies onto the chassis of the bogie so that this assembly is longitudinally slidable and thus causes the one axle having one of its ends connected thereto to pivot forwards or rearwards out of its normal transverse position relative to the transversally opposite supporting assembly which holds the other end of the one axle and then acts as a pivot. An operating arm attached to the frame near the one supporting assembly is used for moving via a linking mechanism the one supporting assembly in such a direction as to cause the one axle held by this supporting assembly to pivot in the same direction but at an angle smaller than and proportional to the frame with respect to the chassis of the bogie.