| 摘要 |
PROBLEM TO BE SOLVED: To make quick elevating lowering operation by a method wherein a shaft, having screws positioned on both left and right side surfaces, is turned through the movement of a lever, operated into left-and-right directions, to move legs equipped with bearing units having screw grooves engaged with the shaft. SOLUTION: An operation lever 1 is attached to the rotary supporting point 2a of a shelf plate 2. When a handle 1a is moved to the position 1' at the left side of the shelf plate, a lever 3 is moved to a position 3' by a retaining rod 1b, engaged with a lever 3. Then, a linear gear 4 is moved to a position 4' whereby a gear unit 5a, integrated with the screw shaft 5, is turned. As a result, a leg, having a change nut unit 6a, is moved to a position 6' whereby the shelf plate 2 is elevated. In this case, the operation lever 1 is provided with a projected unit 1c, engaged with the ratchet unit 2b, whereby the shelf plate 2 will not be returned to the initial position thereof unless the operation lever 1 is pushed down once.
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