| 摘要 |
PROBLEM TO BE SOLVED: To surely maintain a locked condition even when an operating lever is set at a small angle. SOLUTION: A projected part 64 is formed at the tip end of a large diameter part 68A of a lock bolt 68, which is fixed to the tip end of a telescopic lever 70, and the projected part 64 abuts on a wedge lock 82, which pushes an inner tube 14 for locking. As a result, the frictional force, which is generated on a contact surface between the lock bolt 68 and the wedge lock 82, can be made large. In addition, since the contact surface is provided on the peripheral side of the tip end part of the lock bolt 68, the holding power of the lock bolt 68 can be increased. Accordingly, a lead angle of the lock bolt 68 can be made large, so that the operating angle of the telescopic lever 70 can be set at a small value. |
