| 摘要 |
<p>A device for moving an object relative to a surface, for example for pushing a bar in a bar feed mechanism, comprises a piston mounted for reciprocation within a chamber (2), and a piston rod (8) extending from one end of the chamber. Front and rear locking devices (12, 10) respectively associated with the piston rod (8) and chamber (2) are activated alternately in synchronism with the movement of the piston in opposite directions respectively in the chamber (2).</p> |
