Improvements in Electric Current Graduating Devices or Resistances.

摘要

18,106. Sumner, W. July 31. Regulating- switches.-A rheostat for controlling lamps, heaters, or motors, comprises a base block or rod of porcelain, china, quartz, fibre, slate or other insulating- material with long narrow grooves arranged in concentric curves, zigzag, spiral, or other compact formation and filled with resistance composition. In the dimmer shown, graphite paste in concentric grooves 2, 3 is in contact with studs 4, 5 respectively, arranged in staggered relation, and the outer studs 4 are provided with double spring-contact fingers 6 which are depressed on to the studs 5 by means of a rotary arm. The fingers are arranged so that each stud 4 can be connected to two adjacent studs 5, and the bearing-surface 10 is wide enough to cover two fingers.