| 摘要 |
<p>A control apparatus is disclosed for regulating the movement of a control stem which is biased in a given direction. The apparatus comprises a housing forming a chamber and a plurality of passages. The chamber receives the control stem in its direction of bias, the latter abutting against a restraining sphere disposed in the chamber. A pair of pistons are movably disposed in remaining ones of the passages to maintain the sphere in the chamber. The pistons are movable to allow the sphere to enter a passage so that the stem can move further into the chamber. The pistons can be moved manually or automatically, as by means of a fusible element which melts in response to the heat of a fire.</p> |
