<p>A trolley (1) has a base (2) supported on a plurality of wheels (6). A further wheel (8) is provided. Power is supplied to this further wheel (8) which is supported by a pivotally mounted support member (11). The contact pressure between the further wheel (8) and the ground may be varied between a first contact pressure when power is supplied to the further wheel (8) and a second contact pressure less than the first contact pressure when no power is supplied to the further wheel (8). The further wheel (8) also has a trolley turning position. In this trolley turning position, the trolley is turned about further wheel (8). <IMAGE></p>
