求翻译：The operating efficiency of worm-gear reducers ranges from 50% to as high as 95%. A number of factors influence efficiency, including ratio, input speed, tooth geometry, and lubrication. By far. The most important of these is ratio. A lower-ratio unit (5:1 for example) has more threads on the worm and a higher helix angle compared to a high-ratio unit. Higher helix angles mean less sliding friction and hence, higher efficiency. By comparison, helical gears typically have a %% efficiency per gear mesh. For example, a double-reduction helical reducer has an efficiency approximately 0.98* 0.98= 96%.是什么意思？

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