FIELD OF INVENTION:
The present invention relates to carbon brush holders for rotating electric
machines in general, particularly to notched reaction type carbon brushes
holders for DC machines.
BACKGROUND ART:
The substantial parts of rail routes in Indian and abroad are not electrified.
Essentially diesel electric locos operate in these routes. The diesel engine
coupled with traction alternator work as mobile power house in these diesel
electric locomotives to provide power for traction motors.
In a dc motor carbon brush fitted in brush holder (stationary part) is the current
carrying with the commutator (rotating part). Normally the brush holder is of
radial type, whose carbon brush pocket is normal to the axis of rotation of
machine. But over a period of time due to advancements in technology &
demanding service conditions reaction type brush holders are being more
frequently used. In a reaction type brush holder the carbon brush pocket is at an
angle to the axis of rotation of machine.
The normal reaction type brush holder and associated carbon brush have an in-
built deficiency of erroneous fitment of carbon brush.
The notched reaction type carbon brush holder in accordance with the present
invention seeks to overcome above drawbacks of the prior art.

TITLE:
Notched reaction type carbon brush holder for DC machines ensuring fool-proof
positive fitment of carbon brushes.
FIELD OF INVENTION:
The present invention relates to carbon brush holders for rotating electric
machines in general, particularly to notched reaction type carbon brushes
holders for DC machines.
BACKGROUND ART:
The substantial parts of rail routes in Indian and abroad are not electrified.
Essentially diesel electric locos operate in these routes. The diesel engine
coupled with traction alternator work as mobile power house in these diesel
electric locomotives to provide power for traction motors.
In a dc motor carbon brush fitted in brush holder (stationary part) is the current
carrying with the commutator (rotating part). Normally the brush holder is of
radial type, whose carbon brush pocket is normal to the axis of rotation of
machine. But over a period of time due to advancements in technology &
demanding service conditions reaction type brush holders are being more
frequently used. In a reaction type brush holder the carbon brush pocket is at an
angle to the axis of rotation of machine.
The normal reaction type brush holder and associated carbon brush have an in-
built deficiency of erroneous fitment of carbon brush.
The notched reaction type carbon brush holder in accordance with the present
invention seeks to overcome above drawbacks of the prior art.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING:
The invention will now be described with help of the accompanying drawings
which depict an exemplary embodiment of the invention. However, there can be
several other embodiment, all of which are deemed covered by the description.
Fig 1. shows the sketch of normal reaction type brush holder (01),brush holder
pocket (02), its matched carbon brush (03) and their associated fitment to be
fitted on commutator (04) as in prior art. Figl (b) & (c) are the views from-X,
fig 1 (a) is the side view of carbon brush holder (01) assembly, YY - shows the
corners perpendicular to each other of carbon brush pocket (02) and Y-shows
the corner of carbon brush (03).
Fig 2. shows the sketch of normal reaction type brush holder pocket (02) with
its sides (carbon brush Fig.2- (03)) reversed by 180 degree and the erroneous
associated fitment as in prior art.
Fig 3. shows the sketch of notched reaction type brush holder(07), chamfered
brush holder pocket (05), its matching chamfered carbon brush (06) and their
associated fitment as invented. Fig 3, (b) and (c) are viewed from X, Fig 3 (a) is
the side view of the brush holder (07) assembly. D D is the innerface having a
chamfer (08) of suitable degree of carbon brush pocket (05) and □ is the
outerface having chamfer (09) of carbon brush (06) at suitable degree
to match with the brush pocket (05).
Fig 4. shows the sketch of notched reaction type brush holder(07), notched
brush holder pocket (05), its matched carbon brush (06) with its sides reversed
by 180 degree and the full proof arrangement after invention to eliminate any
chance of erroneous carbon brush fitment.

In Fig.l a reaction type carbon brush holder (01) the carbon brush pocket(02) is
at an angle to the rotation of the machine ie, of the commutator (04). When the
carbon brush (03) is fitted with correct matching sides with that of the carbon
brush holder pocket (02), the contact of carbon brush surface with that of
commutator (04), is surface contact (10).
In the prior art as shown is fig 2, erroneous fitting by rotating the sides of the
carbon brush (03) by 180 degree in the brush holder pockets (02), the brush
(03) can be fitted, which will lead to a line contact of the carbon brush (03) with
the commutator (04), instead of matching surface contact (10), which distributes
the current loading un-envenly.
The invention discloses a notched reaction type carbon brush holder (06) as
shown in fig-3, which eliminates fully any chance of erroneous carbon brush (06)
fitment as shown in fig 4.

WE CLAIM:
1. A notched reaction carbon brush holder (07) for DC machines comprising
a carbon brush pocket (05) and a carbon brush (06), wherein the carbon
brush pocket being at an angle to the axis of rotation of the commutator
(04) of the machine, characterized in that the said carbon brush pocket is
provided with a chamfer (08) on the inner face of the pocket and in that
the said carbon brush is provided with a chamfer (09) on the outer face of
the carbon brush, the two chamfers (08,09) matching with each other for
fool-proof fitment of the brush in the pocket.
2. A carbon brush holder as claimed in claim 1, wherein the carbon brush
(06) has a bottom contact surface (10) which has a contour always
matching with the corresponding contour of the commutator.

A notched reaction carbon brush holder (07) for DC machines comprising a
carbon brush pocket (05) and a carbon brush (06), wherein the carbon
brush pocket being at an angle to the axis of rotation of the commutator
(04) of the machine, characterized in that the said carbon brush pocket is
provided with a chamfer (08) on the inner face of the pocket and in that the
said carbon brush is provided with a chamfer (09) on the outer face of the
carbon brush, the two chamfers (08,09) matching with each other for foolproof
fitment of the brush in the pocket.