The inner seal (58) and the opening (66) are mounted in a chamber, and the chamber is closed by a second, outer seal (60) that provides a backup in case of failure of the inner seal (58).

该内密封件(58)和该开口(66)安装在腔室内，该腔室由第二外密封件(60)封闭，所述第二外密封件在所述内密封件(58)失效的情况下提供候补。

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All that was needed to make a mechanical energy-storage system was a good enough rotational seal, so the flywheel could spin freely inside a vacuum chamber with no air resistance.

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