| 摘要 |
PROBLEM TO BE SOLVED: To realize both of a low pressing force/high speed motion until completion of working a work and a high pressing force/low speed motion at the time of press working of a work by a constant power of a motor. SOLUTION: An oil chamber 5 is provided in a casing 1, and a first piston 4 is provided in the casing 1 so as to pass through the oil chamber 5. A nut 3 is fixed to the rear end of the first piston 4, and this nut 3 is screwed onto a ball screw shaft 2. The ball screw shaft 2 is connected to a motor. The fore end of the first piston 4 is engaged with the rear end of a second piston 6. The first piston 4 has a pressuring surface 4a, and a pressure receiving surface 6a with an area larger than this pressuring surface 4a is provided at the rear end of the second piston 6.
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