Patent ID: 7364147

Claim:
A workpiece support device comprising: a support stand having a first cylinder chamber in which a first piston is reciprocably accommodated and a second cylinder chamber in which a second piston is reciprocably accommodated; a support rod attached to the first piston so as to project from the support stand; a non-compressible working medium sealed in a first medium chamber partitioned and formed by the first piston and a second medium chamber partitioned and formed by the second piston; a communication path causing the first medium chamber and the second medium chamber to communicate with each other and guide the working medium between the medium chambers, the communication path being within the support stand and forming a sealed, constant volume system with the first and second medium chambers; pressing means applying a projection-directional pressing force to the support rod as well as the first and second pistons; and an opening/closing valve positioned in the communication path between the first medium chamber and the second medium chamber, and having one operating position where the communication path is closed to fix the support rod and another operating position where the communication path is opened to allow movement of the support rod.