| 摘要 |
A web tension isolator or amplifier includes a rotatable pulley engageable with a driver pulley in response to tension forces in a web that is wrapped on the driven pulley. The mechanism maintains the film tension ratio (i.e., the ratio of the tensions in the web portions on the two sides of the driven pulley) substantially constant regardless of the magnitude of the web tension. The mechanism automatically and quickly adjusts the web tension for any variations in the tensions of the web portions at either side of the driver pulley. The mechanism can be used (for example) in a motion picture projector between the film gate and a supply reel and/or a take-up reel.
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