Carbon brush for use in electric motors

Claim 2

A carbon brush for use in electric motors, comprising an elongated brush body having a leading end face adapted to contact a rotating collector, and a trailing end face; a stepped recess extending from said trailing towards said leading end face and having a wider first portion extending inwardly from said trailing end face, a narrower second portion extending inwardly from said first portion, a shoulder at the juncture of said portions, and a bottom surface domed in direction towards said trailing end face; a correspondingly stepped pressure member slidably accommodated in said recess and having first and second sections located in the respective portions, a stop, and a forward end surface, said surFaces being so configurated that in response to wearing away of said leading end face to the level of said bottom surface, said forward end surface will become exposed over its entire cross-sectional area substantially at once; biasing means acting upon said pressure member and urging said forward end surface into abutment with said bottom surface, said stop being normally spaced from said shoulder but being adapted to bear upon the same in response to exposure of said forward end surface and consequent forward displacement of said pressure member by said biasing means.

Claim 3

A carbon brush as defined in claim 1, said biasing means being a biasing spring accommodated in said recess; and further comprising cooperating abutment portions on said pressure member and in the region of said trailing end face and against which said biasing spring bears.

Claim 4

A carbon brush as defined in claim 1, said pressure member being composed of electrically insulating material.

Claim 5

A carbon brush as defined in claim 2, said pressure member having a cylindrical portion in the region of said trailing end face, and said spring being a helical spring surrounding said cylindrical portion.

Claim 6

A carbon brush as defined in claim 1, said brush body having a rear end portion provided with said trailing end face; and further comprising an abutment member for said biasing means overlying said trailing end face and embracing said rear end portion in clasping relationship.

Claim 7

A carbon brush as defined in claim 5, said rear end portion having a dove-tail shaped cross-section, and said abutment member being substantially C-shaped and embracing and clasping said rear end portion in interlocking engagement therewith.

Claim 8

A carbon brush as defined in claim 1, wherein said stop and shoulder are planar.

Claim 9

A carbon brush as defined in claim 1, wherein said stop and shoulder slightly converge in direction towards said bottom surface.

Claim 10

A carbon brush for use in electric motors, comprising an elongated brush body having a leading end face adapted to contact a rotating collector, and a rear end portion provided with a trailing end face; a stepped recess extending from said trailing towards said leading end face and having a wider first portion extending inwardly from said trailing end face, a narrower second portion extending inwardly from said first portion, a shoulder at the juncture of said portions, and a bottom surface domed in direction towards said trailing end face; a correspondingly stepped pressure member composed of electrically insulating material slidably accommodated in said recess and having a cylindrical first section and a second section located in the respective portions, a stop, and a forward end surface, said surfaces being so configurated that in response to wearing away of said leading end face to the level of said bottom surface, said forward end surface will become exposed over its entire cross-sectional area substantially at once; and an abutment member overlying said trailing end face and embracing said rear end portion in clasping relationship; a helical biasing spring accommodated in said recess, surrounding said cylindrical first section and bearing upon said abutment member and upon said pressure member and urging said forward end surface into abutment with said bottom surface, said stop being normally spaced from said shoulder but being adapted to bear upon the same in response to exposure of said forward end surface and consequent forward displacement of said pressure member by said biasing spring.

Claim 11

A carbon brush for use in electric motors, comprising an elongated brush body having a leading end face adapted to contact a rotating collector, and a rear end portion provided with a trailing end face; a stepped recess extending from said trailing towards said leading end face and having a wider first portion extending inwardly from said trailing end face, a narrower second portion extending inwardly from said first portion, a shoulder at the juncture of said portions, and a bottom surface domed in direction towards said trailing end face; a correspondingly stepped pressure member composed of electrically insulating material slidably accommodated in said recess and having a cylindrical first section and a second section located in the respective portions, a stop, and a forward end surface, said surfaces being so configurated that in response to wearing away of said leading end face to the level of said bottom surface, said forward end surface will become exposed over its entire cross-sectional area substantially at once; and an abutment member overlying said trailing end face and embracing said rear end portion in clasping relationship; a helical biasing spring accommodated in said recess, surrounding said cylindrical first section and bearing upon said abutment member and upon said pressure member and urging said forward end surface into abutment with said bottom surface, said stop being normally spaced from said shoulder but being adapted to bear upon the same in response to exposure of said forward end surface and consequent forward displacement of said pressure member by said biasing spring.

Claim 12

A carbon brush for use in electric motors, comprising an elongated brush body having a leading end face adapted to contact a rotating collector, and a rear end portion having a dove-tail shaped cross-section and provided with a trailing end face; a recess extending from said trailing towards said leading end face and having a bottom surface; a pressure member slidably accommodated in said recess and having a forward end surface, said surfaces being so configUrated that in response to wearing away of said leading end face to the level of said bottom surface, said forward end surface will become exposed over its entire cross-sectional area substantially at once; biasing means; and an abutment member for said biasing means, said abutment member being substantially C-shaped and embracing and clasping said rear end portion in interlocking engagement therewith, said biasing means acting upon said pressure member and urging said forward end surface into abutment with said bottom surface.

Claim 13

A carbon brush for use in electric motors, comprising an elongated brush body having a leading end face adapted to contact a rotating collector, and a rear end portion having a dove-tail shaped cross-section and provided with a trailing end face; a recess extending from said trailing towards said leading end face and having a bottom surface; a pressure member slidably accommodated in said recess and having a forward end surface, said surfaces being so configUrated that in response to wearing away of said leading end face to the level of said bottom surface, said forward end surface will become exposed over its entire cross-sectional area substantially at once; biasing means; and an abutment member for said biasing means, said abutment member being substantially C-shaped and embracing and clasping said rear end portion in interlocking engagement therewith, said biasing means acting upon said pressure member and urging said forward end surface into abutment with said bottom surface.

Claim 14

A carbon brush as defined in claim 10, said recess being stepped and having a wider first portion extending inwardly from said trailing end face, a narrower second portion extending inwardly from said first portion, and a shoulder at the juncture of said portions; and wherein said pressure member is correspondingly stepped and has first and second sections slidably located in the respective portions, and a stop normally spaced from said shoulder but adapted to bear upon the same in response to exposure of said forward end surface and consequent forward displacement of said pressure member by said biasing means.

Claim 15

A carbon brush as defined in claim 11, said bottom surface being domed in direction towards said trailing end face.

Claim 16

A carbon brush as defined in claim 12, wherein said forward end surface is at least substantially planar.