| 摘要 |
PROBLEM TO BE SOLVED: To set a work bench in a low position so as to be durable even against a large load, by arranging concentrically a plurality of doughnut-shaped can barrel units, and arranging a plurality of hydraulic jacks relating to an upper plate surface of each can barrel unit so as to provide an equal space and make upper/lower directional action alternately different. SOLUTION: A hydraulic jack is mounted in an equal space position in a circumferential direction in a doughnut annular can barrel unit, to be arranged so as to provide a stroke of a piston rod different alternately in a vertical direction. Action of a down-facing hydraulic jack 4b of the can barrel unit 3 strongly presses the ground surface and floor surface 9 by a fixed bench 8, and in this condition an up-facing hydraulic jack 4a lifts the can barrel unit 5 to a fixed height direction through a connection unit 7. Here, a supporting hydraulic jack 10 in the can barrel unit 5 is further higher lifted by action of a down-facing hydraulic jack 6b of the can barrel unit 5 and action of an up-facing hydraulic jack 6a, in addition, action of the supporting hydraulic jack 10 lifts a work bench 11 on the piston rod to the uppermost height.
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