| 摘要 |
A subterranean stop valve in a district heating system is laid out for servocontrolled operation from a nearby walkway cabinet, by hydraulic actuation of a double acting free piston block (8), which is displaceable with high power just as much as required for a full change-over of the valve (2). Just prior to the full change-over being reached it is automatically arranged that at the hydraulic return end of the piston the return flow (28) is shifted to now be forced (at 42) into a remote indicator (48), whereby a slide body (54) in the latter is changed over, affected by a high force immediately at the end of the full valve change-over. Hereby a robust and long-time durable change-over and indicator system is achievable. <IMAGE> |
