Stromag EDB Series, Инструкция по монтажу

Страница: 97 / 104

8.4.2 Check brush wear, box-type holder
Inspection of
carbon brushes The wear of the carbon brushes is too high when it ex-
ceeds 2 to 7 mm per 1000 operating hours.
1. Measure the brush wear and compare it to the oper-
ating time.
NOTE
Example for the calculation of the theoretical
operating life of the brush:
In a usable length of 20 mm for example, the
theoretical operating life of the brush equals
between 2900 and 10000 operating hours.
Fig. 26
If the wear and tear exceeds the above reference value, the following sources of defect may apply:
• excessive radial displacement of the slip ring in mounted condition, see section 6.3.2.
• influence of oil and dirt, dusty air
• heavy oscillations
• aggressive gases and vapours
• relative humidity is too low (al least 45 % at 20 °C and 25 % at 30 °C)
• the brush pressure is too high, see section 5.3.2
• rough slip ring surface (Ra 0,8 to 1,2 μm / Rz up to 8 μm)
Wear limits for carbon brushes in box-type holder
The carbon brushes in the box-type holder size 05 to 20 are guided with spiral springs to balance the wear. The
end top of the spring lifting indicates the wear limit. Once this limit has been reached, the carbon brush can no
longer be pushed onto the slip ring and must be replaced.
New carbon brushes only have a punctiform or linear contact surface to the slip ring. They thus have to be
ground-in, see section 8.4.5.
8.4.3 Check brush wear, spark-type brush holder
The spark-type brush holders for dry operation are composed of a housing and an axially mobile carbon brush
with round cross sectional area, which is guided through a pressure spring to balance the wear.
Inside the housing is a hook on for the wear path. Once this has been reached, the carbon brush can no longer
be pushed onto the slip ring and problems occur in the power flux, such as brush sparking or power disruptions.
The carbon brush must be replaced immediately when this point is reached.
In new condition, the carbon brush and slip ring only have a punctiform or linear contact surface. To avoid dam-
age to the running surface through the resulting high current density, carbon brushes with round cross sectional
areas have to be ground-in, see section 8.4.5.
39
Mounting instructions Electromagnetic multi-disc clutch EKE/EKB, EDE/EDB • No. 500-00000 C • 10/2017