Page 16 - KNORR Pneumatic Disc Brake

5

Functional and Visual Check

5.1.4. Check the disc at each change of pads for grooves
and cracks. If necessary replace the disc.
The figure shows possible surface conditions of the brake max. 1.5 mm
disc. A B
A = Small cracks spread over the surface are allowed 1 1
1
B = Cracks less than 1 5 mm deep or wide, running max. 0.75 x a
1
in a radial direction are allowed
Cracks to a max. length of 0.75 x’a’ are allowed a
(a = width of the friction ring)
C = Unevenness of the disc surface less than 1 5 mm
1
deep is allowed
D = Cracks going through to the cooling duct or onto
1
the inner or to the outer edge of the friction ring are D 1 C 1
not allowed and the disc MUST BE REPLACED.

Note:
In case of surface conditions A , B or C , the disc can
1
1
1
continue to be used until the minimum thickness E = 37
mm is reached.
Knorr-Bremse discs are normally service-free and grinding
when changing pads is not necessary. However, grinding C1
could be useful, e.g. to increase the load-bearing surface of
the pads after severe grooving on the entire friction surface
has occurred. To meet safety requirements, the minimum B1
thickness after machining must be greater than 39 mm.
In addition, the recommendations of the vehicle manu-
facturer about the machining of the brake disc MUST be D1
followed.

Grinding of a Knorr-Bremse Splined Disc® is not
allowed.

The adjacent picture shows some examples of cracks and 5.1.4 - Tolerances and examples of cracks and grooves
grooves on a brake disc. on a brake disc.

If these recommendations are ignored, there is
a risk of an accident. If the brake pads and/or
the brake disc are worn down excessively, brake
performance will be reduced and may be lost
completely.

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