A pipe crawler tractor may comprise a half tractor assembly having a first base drive wheel, a second base drive wheel, and a top drive wheel. The drive wheels are mounted in spaced-apart relation so that the top drive wheel is positioned between the first and second base drive wheels. The mounting arrangement is also such that the first and second base drive wheels contact the inside surface of the pipe at respective first and second positions and so that the top drive wheel contacts the inside surface of the pipe at a third position, the third position being substantially diametrically opposed to the first and second positions. A control system connected to the half tractor assembly controls the rotation of the first base wheel, the second base wheel, and the top drive wheel to move the half tractor assembly within the pipe.
CONTRACTUAL ORIGIN OF THE INVENTION
The United States Government has rights in this invention disclosed under contract number DE-AC07-84ID12435 between the U.S. Department of Energy and Westinghouse Idaho Nuclear Company, now contract number DE-AC07-94ID13223 with Lockheed Idaho Technologies Company.