Patent ID: 7926426
Filing Date: 2011-04-19
Classification: E01B

Abstract:
1. An apparatus for traveling along a railway bed having first and second railroad rails, the apparatus comprising: a frame; a first set of rail engaging wheels mounted on the frame and adapted to ride on the first rail; a second set of rail engaging wheels mounted on the frame and adapted to ride on the second rail; a crawler adapted to support the frame for travel along the railway bed when one of the rails is removed from the railway bed; a carriage which carries the crawler; a lowered position of the carriage in which the crawler is adapted to contact the railway bed; a raised position of the carriage in which the crawler is adapted to be out of contact with the railway bed; a first pneumatic lift mounted on the frame for raising the carriage from the lowered position to the raised position; wherein the first pneumatic lift is directly above the crawler in the lowered and raised positions; and a first elastomeric bladder which extends between the frame and carriage and defines an interior chamber for receiving a gas for inflation and deflation of the first bladder; wherein the carriage is movable relative to the frame in response to inflation of the first bladder.