| 摘要 |
In the preferred form, a closed tube is provided with fixed shoulders on the opposite sides of a ring-shaped elastic seal member and a washer surrounding and having close fit with a rod extending into a viscous silicone thermal expansion fluid. At the open end of the tube the rod has a shoulder adapted on the inward movement to engage a double throw switch to move it from engagement with an outer contact into engagement with an inner contact. The rod is urged inwardly by a coil spring having its inner end pressing against a spring retainer fixed to the rod and having its outer end pressing against a second seal ring surrounding the rod for preventing leakage into an outer part of the tube.
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