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Brushes of hard carbon
semimanufactured having CDR symbol, are strong and rezistent
at long running. Their characteristics, limit them at low and high speed. Hard
carbon materials are manufactured in four qualities: CDR-1, CDR-2, CDR-3, CDR-4.
Hard carbon brushes
are used at the motors
of the electric home apparatus, for ignition
distribuitor and magnetou at show electrical rotative machines whithout auxiliary
poles.
Table
with parameters of running recommanded for
hard carbon materials in normal conditions of
running
|
Group
of semimanufactured
|
Mark
|
Density
of curent
|
Peripheral
speed max.
|
Pressure
on brush
|
|
|
A/cm²
|
m/s
|
kN/m²
|
|
0
|
1
|
2
|
3
|
4
|
|
HARD
CARBON
|
CDR
- 1
|
5
|
25
|
30
- 60
|
|
CDR
- 2
|
6...8
|
15
|
25
- 40
|
|
CDR
- 3
|
6
|
15
|
20
- 30
|
|
CDR
- 4
|
8
|
20
|
30
- 40
|
Phisical characteristics
of the hard carbon materials could be determined using a tubes
of sizes 4x8x32 mm or 10x10x64 mm according to STAS 10223/1-75.
Fuctional characteristics: falling voltage, friction coefficient and middle
wear speed values
are determinated in laboratory conditions on two pieces of testing brushes
on sizes
12,5x25x40 mm according to STAS 10223/3-84. For the folling voltages, friction
coefficient
and medium wear speed values (point 6,7 and 8) are necesary the following conventional
conditions of testing:
|
TESTING
CONDITIONS
|
VALUES
|
|
peripheral
speeds
|
15
or 25 m/s
|
|
density
of current
|
15,
16 or 20 A/cm²
|
|
pressure
on brush
|
25-
60 kN/m²
|
|
current
|
continous
|
|
temperature
|
60°C
|
|
|
