| 摘要 |
A gas lighter has a flint (6) and spark wheel (7) for igniting petroleum gas leaving a reservoir. Thumb wheels (10) are mounted coaxial with the spark wheel; each thumb wheel can pivot about its own axis independently of the spark wheel. A rotational frictional engagement device connects the thumb wheels to the spark wheel only when the radial force exerted on the thumb wheels exceeds a preset value. The engagement device may be mechanically roughened surfaces or a surface covering (21) of nickel, zinc, chromium or polytetrafluoroethylene. The thumb wheels may be of stainless steel, brass, alloys of aluminium with zinc or beryllium, etc.
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