STRAIGHT ADVANCE MOVEMENT MAINTAINING MECHANISM

PROBLEM TO BE SOLVED: To maintain straight advance movement of a coating apparatus or the like which makes straight advance movement on a peripheral surface of a structural member such as a steel pipe. SOLUTION: A straight advance movement maintaining mechanism of a moving body, which is mounted on an outer peripheral surface of the structural member of a columnar shape or a cylindrical shape and which makes straight advance movement in an axis line direction on the peripheral surface of the structural member, is provided with a guiding roller 10, which is provided at least at either one among a front end part or a rear end part of the moving body in a straight advance movement direction and which rotates on the peripheral surface of the structural member when the moving body makes straight advance movement and further which gyrates in a direction along a shifting direction of the moving body when a moving direction of the moving body shifts from a rectilinear direction to a peripheral direction, and a pendulum 21 having a weight 23 which oscillates in a peripheral direction opposite to the guiding roller 10 by being linked with the guiding roller 10. Restoring force onto a vertical line acts on the weight 23 according to a principle of a pendulum and a direction of gyration of the guiding roller 10 is changed by the restoring force, a direction of the moving body is changed in following to the guiding roller 10 and straight advance movement of the moving body is maintained. COPYRIGHT: (C)2007,JPO&INPIT