| 摘要 |
PURPOSE:To constitute a segment so that the same can bear a heavy load in a radial direction and replacement of a cam plate resulting from a change of dimensions of a belt can be performed swiftly, by bearing shaping reaction force by the cam plate other than the one for expansion or contraction driving of the segment. CONSTITUTION:At the time of holding of a belt, a cam plate 10 is revolved, a supporting bar 2 is moved inside in a radial direction and the belt is held by performing contraction of the diameter of a segment. At the time of locking (against reaction force expanding the diameter), a disc plate 13 is revolved and a cam part 19 of a cam plate 15 is fitted to a position I. In this instance, force which acts upon the segment and is apt to expand the diameter is born by the cam part 19 of the cam plate 15 through a cam roller 9 and force which is apt to revolve against the cam plate 10 is not generated. At the time of release of the locking, the disc plate 13 is revolved and the cam part of the cam plate 15 is removed from the cam roller 9 at a position II. At the time of the release of the belt, the cam plate 10 is revolved, the supporting bar is moved outside in a radial direction and the diameter of the segment 1 is expanded. |
