| 摘要 |
A trimmer potentiometer or like variable resistor, which is of the kind having a worm 21 driving an elastomeric worm wheel 10 carrying a wiper contact to slide on an arcuate resistance element, has the gear teeth formed on circumferentially-spaced rim sections 23, 24, 25 projecting cantileverwise from an axially thick unbroken rim 10b of a radial flange on the main body 10c of the wheel, some sections 23 having only a few gear teeth and being separated by sections 24, 25 having larger numbers of gear teeth. The extent of rotation of the wheel 10 is limited to less than 360 DEG and the sections 23 with few teeth are arranged to be in mesh with the worm at the limits of wheel rotation so as to give a de-clutching effect by inward deflection of these sections on over rotation of the worm.
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