How to Select Carbon Brushes for Motors and ... - Morgan AM&T

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brushes, also known as pads, designed to soften the impact
from a rough commutator, giving longer brush life and
reducing brush breakage. However, rubber hard top
brushes are not a “cure-all” solution. For more information
on rubber hard top brushes, refer to the technical data
sheet on Rubber Hardtop Brush Applications.
Engineered Brush Grades
Electrographitic
surface. On critical threading conditions, it is recommended
that fluted brushes be used, as the brush allows for a quick
brush fit and a Spec. more even film. Trans.
Res.
Strength Con-
It Brush is not necessary Ω-in. to Dens. remove the lbf/in² brush after tact the Fric- fluted
portion Grade is worn (µΩ-m) away, but g/cm³ can be (kgf/cm²) operated Drop to the normal tion
minimum wear length.
0.0020
3700
234
1.48
VH L
Pre-Radius Brushes
(51)
(260)
An
0.00075
2700
258 alternate method to form 1.60 the brush to the surface H of L the
commutator is
(19)
to machine a radius
(191)
(pre-radius) in the brush
face. This machining applies a radius that is equal to or
slightly 0.0030
1700
561 larger than the commutator. 1.54 Adding VH a pre-radius M
does not remove (76) the need to sand (120) in a brush, but it does
significantly 0.0029 decreases the time 1600 needed to match the
contact 569 surface. (74) 1.53
VH M
(113)
Rubber 0.0027
571 Hardtop Brushes 1.57
(66)
2400
(169)
VH M
Morgan 0.0022
3200
581 AM&T manufactures 1.61 a full line of rubber VH hardtop M
brushes, also known (56) as pads, designed (225) to soften the impact
from 0.0024
3700
590 a rough commutator, 1.62 giving longer brush VH life M and
reducing brush (61) breakage. However, (260) rubber hard top
brushes 0.0020
4000
591 are not a “cure-all” 1.66 solution. For more VH information M
on rubber hard (51) top brushes, refer (282) to the technical data
sheet 0.0026
1400
A451
on Rubber Hardtop
1.50
Brush Applications.
VH
(66)
(99)
L
Engineered Brush Grades
Electrographitic
Brush
Grade
234
258
561
569
571
581
590
591
A451
Spec.
Res.
Ω-in.
(µΩ-m)
0.0020
(51)
0.00075
(19)
0.0030
(76)
0.0029
(74)
0.0027
(66)
0.0022
(56)
0.0024
(61)
0.0020
(51)
0.0026
(66)
Dens.
g/cm³
1.48
1.60
1.54
1.53
1.57
1.61
1.62
1.66
1.50
Trans.
Strength
lbf/in²
(kgf/cm²)
3700
(260)
2700
(191)
1700
(120)
1600
(113)
2400
(169)
3200
(225)
3700
(260)
4000
(282)
1400
(99)
Con-
tact
Drop
Friction
VH L
H L
VH M
VH M
VH M
VH M
VH M
VH M
VH L
SRB does not limit the apparatus output since it is made of
the material compatible with the other brushes. SRB’s will
remove metal as they slowly grind off the high areas. For
more information on SRB’s, refer to the technical data sheet
on Surface Rounding Brushes.
Surface Cleaning Brushes
Surface Normal
The surface cleaning brush (SCB) is a preventative
Speed Current Description and Application
maintenance tool designed to give the best possible
ft/min Density
performance in rotating equipment exposed to severe
(m/sec) A/in²
contamination. The SCB fits in the brush holder of the
(A/cm²) Recommended for:
motor or generator and cleans the commutator and/or
6000
collector
80
ring during
A variety
operation.
of industrial
The SCB
and FHP
does
machines.
not limit the
(30)
apparatus
(12.5)
output.
Good
For
general
less
purpose
aggressive
grade.
cleaning, please
refer to the laminated
Copper alloy
grades
slip
listed
rings
previously.
with current
For
density
more
6000
information
80
on SCB’s,
up to 75
refer
APSI
to
and
the
speeds
technical
up
data
to 6000
sheet on
(30)
Surface
(12.5)
Cleaning
ft/min.
Brushes.
Also used on lightly loaded
machines.
8000
Surface
80
Rounding
Where
Brushes
excellent commutating ability is of
(41) (12.5) primary importance.
Contaminated atmospheres where slight
8000 The surface 80 rounding brush (SRB) is another preventative
polishing action is necessary.
(41) maintenance (12.5) tool designed to give the best possible
performance in rotating equipment (that has a rough riding
7000 surface). 80 The SRB Industrial fits in and the transit brush applications.
holder of the motor or
(36) generator (12.5) and smooths the commutator and/or collector
6000 ring to a 80 specific Mill-type roundness motors as and the machine generators operates. where The
(30) SRB does (12.5) not limit normal the commutation apparatus output is needed. since it is made of
6000 the material 80 compatible Where high with strength the other and brushes. superior SRB’s will
(30) remove (12.5) metal as commutating they slowly ability grind is off needed. the high areas. For
6000 more information 80 Where on SRB’s, severe refer mechanical to the technical conditions data sheet
(30) on Surface (12.5) Rounding require Brushes. a high strength grade..
8000 80 Where humidity is low or where filming
(41) (12.5) conditions are difficult.
Surface
Speed
ft/min
(m/sec)
6000
(30)
6000
(30)
8000
(41)
8000
(41)
7000
(36)
6000
(30)
6000
(30)
6000
(30)
8000
(41)
Normal
Current
Density
A/in²
(A/cm²)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
80
(12.5)
Description and Application
Recommended for:
A variety of industrial and FHP machines.
Good general purpose grade.
Copper alloy slip rings with current density
up to 75 APSI and speeds up to 6000
ft/min. Also used on lightly loaded
machines.
Where excellent commutating ability is of
primary importance.
Contaminated atmospheres where slight
polishing action is necessary.
Industrial and transit applications.
Mill-type motors and generators where
normal commutation is needed.
Where high strength and superior
commutating ability is needed.
Where severe mechanical conditions
require a high strength grade..
Where humidity is low or where filming
conditions are difficult.
5
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