| 摘要 |
A helical resistance element of wire sufficiently stiff to make the element self-supporting is traversed by a contact member threadedly engaging the inside of the helix at circumferentially spaced points. Contact is maintained by the fact that the member is a tight fit in the element, actually expanding it somewhat from its normal diameter. The contact member is mounted on a conductive shaft, for which a low friction, high pressure and high conductivity bearing of silver graphite material is provided at one end of the helix, external connection to the contact member being made through the bearing and the shaft. Assembly is done by temporarily expanding the end turns of the coil to permit insertion of the associated parts, which are retained by the spring contraction of the coil when released.
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