| 摘要 |
<p>The vehicle has at least one resilient driving cup [2, 3] mounted around the body [1] of the vehicle so as to contact the interior wall of the pipeline and thus provide a pressure differential across the driving cup which will propel the vehicle along the pipeline. An annular array of ducts [19] extends through the body of the vehicle to by-pass fluid through the driving cup, each duct being provided with a control valve [20] for regulating the flow of fluid through the duct. A control arrangement [21] is provided for opening and closing the control valves in dependence on the speed of the vehicle, thereby to adjust the speed of the vehicle in accordance with a desired speed. </p> |
