Commutating brush

Claim 1

IN COMBINATION WIHT AN ADJUSTABLE VOLTAGE AUTOTRANSFORMER HAVING A COMMUTATOR SURFACE FORMED OF A PLURALITY OF SEPARATE COMMUTATING SEGMENTS WITH A SPACING BETWEEN ADJACENT SEGMENTS AND WITH AN ELECTRICAL POTENTIAL EXISTING BETWEEN ADJACENT SEGMENTS, THE IMPROVEMENT COMPRISING A COMMUTATING BRUSH FORMED OF A SUBSTANTIAL NUMBER OF SEPARATE ELECTRICAL CONDUCTING WIRES, EACH WIRE HAVING A FIRST END AND A FIRST TERMINAL PORTION AND A SECOND END AND A COVERING OF ELECTRICAL INSULATING MATERIAL WITH THE ENDS FREE OF INSULATING MATERIAL, MEANS FOR MAINTAINING THE TERMINAL PORTIONS OF THE WIRES SUBSTANTIALLY RIGID TO HAVE THE FIRST ENDS FORM A SUBSTANTIALLY PLANAR ELECTRICALLY CONDUCTING SURFACE FREE OF INSULATION, MEANS FOR ELECTRICALLY CONNECTING TOGETHER THE SECOND ENDS OF THE WIRES TO A COMMON CONNECTOR, MEANS FOR MOUNTING THE BRUSH ON THE AUTOTRANSFORMER TO HAVE THE PLANAR SURFACE SLIDABLE ON AND IN ELECTRICAL ENGAGEMENT WITH THE COMMUTATOR SURFACE, SAID PLANAR SURFACE BEING OF A WIDTH TO SPAN AT LEAST TWO SEGMENTS WITH THE FIRST END OF EACH WIRE HAVING A WIDTH LESS THAN THE WIDTH OF THE SPACING, SAID WIRES BEING DIMENSIONED AND FORMED OF ELECTRICAL RESISTANCE MATERIAL TO HAVE THE RESISTANCE OF THE WIRES BETWEEN THE ENDS SUBSTANTIALLY LAGER THAN THE CONTACT RESISTANCE BETWEEN THE FIRST ENDS OF THE COMMUTATING SURFACE WHEREBY THE PASSAGE OF CURRENT THROUGH THE WIRES GENERATES SUBSTANTIALLY MORE HEAT ALONG THE LENGTH OF THE WIRES THAN THE ENGAGEMENT BETWEEN THE FIRST ENDS AND THE COMMUTATING SURFACE.