| 摘要 |
<p>A valve assembly (20, 20') for automatically reversing an actuator (1, 2),in particular a double-acting cylinder, which is operated by a pressure medium. The valve assembly comprises a first and a second port (21, 22), it being possible for each of the first and second ports (21, 22) to be selectively connected to a supply for a pressure medium while the other can be connected to a reservoir, and a third and fourth port (23, 24), which can be connected to the actuator (1, 2). Furthermore, a reversing valve (25) is provided, which is indirectly operated by pressure medium. The reversing valve (25) comprises a sliding body (26) which is able to adopt a first and a second position. The position of the reversing valve (25) is set by means of a first and a second pilot valve (40, 50). There is a back-pressure setting means (67, 70) between the third port (23) and the reversing valve (25), which back-pressure setting means (67, 70) allows pressure medium to flow from the third port (23) to the reversing valve (25), generating a back pressure at the third port (23).</p> |
