| 摘要 |
An automotive vehicle having a short turning radius and equipped with a conventional frame (2) is provided with two front steerable road wheels (3) and two rear drive wheels as well as an additional steerable wheel (6) which is orientable by means of a hydraulically actuated steering mechanism (13). The additional steerable wheel can be turned through a substantial turning angle on each side of a longitudinal median position and is also mounted as to be capable of vertical displacement with respect of the vehicle frame. During periods of specialized-duty service during which the vehicle travels at low speed, the additional steerable wheel is placed in the bottom position in contact with the ground whilst the two front steerable road wheels are lifted above the ground by means of a lifting device for compressing the suspension provided for the front road wheels, with the result that the vehicle then runs on three wheels and affords high manoeuvrability. Outside periods of specialized-duty service, the additional wheel is placed in the top raised position above the ground and the vehicle can then travel at a relatively high speed on its tour road wheels while affording good stability and road-holding characteristics. <IMAGE> |
