Bi-directional conduit traversing vehicle

A vehicle ( 1 ) for travelling along a conduit ( 2 ) such as a pipeline having fluid flowing therein is disclosed. The vehicle comprises a first body carrying a first set of retractable bristles ( 12 ) for engaging an internal wall of the conduit such that the bristles resist movement of the first body in a first direction more than in a second direction, and a second set of retractable bristles ( 13 ) for engaging the internal wall of the conduit such that the bristles resist movement of the first body in the second direction more than in the first direction. A thread follower ( 16 ) carries a third set of resilient bristles ( 18 ) for engaging the internal wall of the conduit such that the bristles resist movement of the thread follower in the first direction more than in the second direction. A turbine ( 5 ) is actuated by fluid flow in the conduit to cause rotation of a reverse traverse screw ( 14 ) to move the first body and thread follower towards and away from each other. The first ( 12 ) and second ( 13 ) bristles are stiffer than the third bristles ( 18 ).