| 摘要 |
PURPOSE:To prevent the positional shift at an earth point even at the time of steering during running, by arbitrarily changing the direction of running rollers regardless of the running drive system of said rollers and always performing the revolving operation of the running rollers around the earth point being a fulcrum. CONSTITUTION:The driving force of a drive apparatus 12 for running roller 8 is transmitted to a shaft body 15 through bevel gears 32, 33, a shift body 35, a sprocket wheel 34 and a transmission cylinder 26 and further transmitted to a roller support shaft 22 through gears 23, 25 to rotate the running rollers 8. The driving force of a drive apparatus for steering allows a cylinder 14 to revolve through a worm wheel 39 and allows the running rollers 8 to revolve through a bracket part 18. Since the centers of the running roller 8 in diameter and width directions position on the extension of the axis of the cylinder in this revolving operation, said revolving operation is always performed around the earth points of the running rollers 8. By this mechanism, the shift of the earth points at the time of steering can be prevented. |
