| 摘要 |
PURPOSE: To rotate a handle shaft in the descending direction without performing release action by an operator, by releasing a reverse rotation unable condition of the handle shaft by a pitch feed mechanism when a handle is switched from an unlock condition to a lock condition. CONSTITUTION: By pressing a handle 7 in a direction of arrow markα, a tapered part of a taper pin 18 is pressed by a boss 15. Accordingly, the taper pin 18 is pressed in a left direction, to swivel a handle arm 19 in the clockwise direction with a support point pin 20 serving as the center, and a releasing link 12 is swiveled in a left direction. In this way, a release arm 9 is swiveled in the clockwise direction with a support point pin 47 serving as the center. Accordingly, the release arm 9 presses a releasing pin 74 of a pawl 75 against a spring 73. In this way, a recessed part of a ratchet 72 is disengaged from a tip end of the pawl 75. Thus, a shaft 86 can be rotated in the descending direction. When pressing is released from this condition, the handle 77 is returned to the original condition by tension of a spring 37.
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