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Rubber Insulators

Rubber was invented in the mid 1800's and has since been used as an electrical insulator.  Early on Goodyear patented a ramshorn insulator with rubber insulation.  There was also a rubber liner for glass threadless insulators.  More recently rubber insulators have been used in place of glass to protect from hunters, BB-guns, and stones.

Here are four pintype rubber insulators as follows (Left to right):

  • No markings, unusual slot top to hold the wire

  • Small threaded style marked "BS-3 // W.U.TEL.CO. 5-A / PAT. 2,218,497 // CONTINENTAL / RUBBER WORKS U.S.A."

  • A slightly larger style with what look like CS sized threads marked "R-5 // CONTINENTAL / RUBBER WORKS U.S.A. // PAT. 2,218,497 / PAT 2,304,483"

  • A full sized version with standard one inch threads marked "R-4 // CONTINENTAL RUBBER WORKS / ERIE PA. U.S.A. // PAT 3,061,667"

Two Mid-span transposition styles as follows (Left to right):

  • Marked "RC-1 CONTINENTAL / RUBBER WORKS U.S.A. // PAT 3,061,667"

  • Marked "RC-1 CONTINENTAL / RUBBER WORKS U.S.A. // PAT. 2,218,497 / PAT 2,304,483"

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