Abstract: A conveying system for placement adjacent to the surface of an object for inspecting that surface is disclosed. The system comprises a parallel rail track formed from cylindrical rails and an inspection trolley riding on that track having two pairs of wheels arranged about the tracks. The first pair of wheels are axially undisplaceable relative to the rail and are formed of trough-shaped surfaces with a circumference of the same radius of the rail. The second set of wheels is displaceable relative to a second rail and engage that rail. The first set of wheels is driven by gears interposed between the wheels and a drive motor and utilize compression generating members to urge the wheels toward each other and toward the rail.