| 摘要 |
PROBLEM TO BE SOLVED: To avoid becoming high at the time of being collapsed. SOLUTION: A leg attitude fixing part 5 is provided with an engaging part 51 for fixing the collapsed attitude of a leg part 4 and an engaging part 52 for fixing the upright attitude of the leg part 4 and slidably supports an engaging member 7 to be alternatively engaged with the engaging part 51 for fixing the collapsed attitude or the engaging part 52 for fixing the upright attitude so as to be removed from each of the engaging parts for fixing attitudes more inward with respect to forward and backward directions than the location of the collapsing of the leg part 4 in a supporting part. Furthermore, the engaging member 7 is elastically pressed in the direction to be engaged with both engaging parts for fixing attitudes by a biasing member 6 more inward with respect to forward and backward directions than the location of the collapsing of the leg part 4. In the case of operation, the engaging member 7 to be engaged with each of the engaging parts for fixing attitudes is moved in the direction to be removed from each of the engaging parts for fixing attitudes against the biasing force of the biasing member 6.
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