| 摘要 |
PURPOSE:To improve rigidity of a front shell by engaging a reinforcing plate in a second cylinder part of the front shell, by superimposing an end surface of the reinforcing plate on an end surface of the front shell, and by bringing a cylinder part in close contact with the inner circumferential surface of the second cylinder part. CONSTITUTION:When an input axis 29 is stepped down to the forward end, a strong force is applied to a stepped part end surface 1k of a front shell 1 toward the left side through a fitting bolt 35, and a large diameter part 1j and a connection portion 1g' between a large diameter part 1j and a head-mount cone part 1g continued from the stepped part end surface 1k are to be enlarged toward the outside in the radial direction with it. However, as the large diameter part 1j is supported by an outer circumferential cylinder part 36b of a reinforcing plate 36 in a close contact state, the large diameter part 1j and the connection portion 1g' to be enlarged are prevented from deformed by the outer circumferential cylinder part 36b of this reinforcing plate 36. Thus, without increasing plate thickness of the front shell 1, rigidity can be improved. |
