| 摘要 |
<p>PURPOSE:To enable specified work as a matter of course, to make a simple structure, to avoid a device furnished with this structure increasing in size and rising in cost, and to improve its generality. CONSTITUTION:This is a differential cylinder formed and constituted so that it contracts as hydraulic pressure from a hydraulic pressure source P is supplied to a rod side chamber R1 through a pressure side oil passage L1 and it extends by differential pressure with the rod side chamber R1 at the time when the hydraulic pressure from the hydraulic pressure source P is supplied to a piston side chamber R2 through an extension side oil passage L2. A valve structure 2 to control extension and contraction of the differential cylinder 1 has a cutoff member consisting of a poppet 18 arranged free to move in a communicating passage 14 to communicate the pressure side oil passage L1 and the extension side oil passage L2 through to each other or a steel ball and others. The cutoff member is formed in order to selectively cut off communication between the communicating passage 14d and the extension side oil passage L2 and the pressure side oil passage L1 at the time of its movement.</p> |
