Bendix Commercial Vehicle Systems ADB22X-V Air Disc Brakes - Manual (Page 13)

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Bendix air disc brakes are precision-engineered braking
mechanisms. The “friction couple” braking characteristics
have been carefully optimized — and the rotor design and
materials have been matched with special formulation
brake pads for optimal performance. In all cases, use
brake pads with the type of backing plate and lining material
originally supplied by the vehicle manufacturer.
CAUTION: When replacing brake pads and rotors,
use only Bendix
® brand replacement pads and rotors
and/or those approved by the OEM. Non-approved
replacement disc pads or rotors can cause excess
wear to brake components, and can increase the risk
of rotors cracking, etc.
4.4 INSPECT THE ROTOR
CAUTION: Follow all safe maintenance practices.
Identify if the rotor is a Bendix ® Splined Disc ® , or Bendix ®
brand conventional rotor (See Section 1.03). Rotors should
be inspected regularly (See Section 2.0 for recommended
inspection schedule) and at each pad change.
4.4.1 Measure the thickness of the brake rotor at the
thinnest point (Dimension “E” in Figure 22). Avoid
measuring near the edge of the rotor as minor
burrs may result in inaccurate measurement.
For
Bendix ® brand rotors, replace the rotor when
the minimum thickness of 1.46 in. (37 mm.) is
reached. For other brands of rotors, refer to the
rotor manufacturer’s guidelines.
4.4.2 Inspect the rotor surface. See Figure 25. The type
of rotor, and also the size, depth and direction of
the imperfections, must all be considered.
NOTE: If surface wear conditions F through J are
in the permitted range, the rotor is still usable until
it reaches the minimum acceptable thickness for the
rotor manufacturer’s guidelines.
4.4.3 Machining (Grinding or Turning) Rotors
Bendix ® brand rotors are normally service-free. In the case
of severe grooving of the entire friction surface, however,
CONVENTIONAL ROTORS may be turned when changing
pads, to increase the load-bearing surface.
FIGURE 25 - EXAMPLES OF ACCEPTABLE AND NON-ACCEPTABLE ROTOR CONDITIONS
Area
F
Area
H
Area G
f
Area J
Cracks reaching
either edge of the
G
H
rotor
are not
acceptable
for either
type of
rotor
Circumferential
grooves, as in Area
J, are acceptable
if less than 0.06 in.
(1.5 mm) deep.
J
• For standard Bendix ® brand rotors,
cracks running in a radial direction —
like spokes of a wheel (see Area H)
— less than
0.06 in. (1.5 mm) deep or
wide are acceptable if they do not reach
either edge (see G). Cracks are only
acceptable if the length of the crack is
less than 75% of dimension “f” (the width
of the rotor contact area).
• For Bendix ® Splined Disc rotors,
radial cracks are only acceptable if they
are less than
0.04 in. (1.0 mm) deep
or wide and if they do not reach either
edge (see G). Crack lengths must be
less than 75% of dimension “f” (the
width of the rotor contact area).
In addition, follow the
recommendations of
the vehicle and rotor
manufacturer.
Note: Axles should
have either all Bendix
Splined Disc (or all
conventional) rotors.
Rotor
Friction
Surface
Width “f”
No action is needed
f o r s m a l l c r a c k s
s p r e a d o v e r t h e
surface (e.g. Area F)
F