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Brake Drum Failure Analysis
Heat-checking is a nor-
mal condition of the
brake drum caused by
constant heating and
cooling of the braking
surface.
Heat checking does
not impair brake perfor-
mance, reuse drum if
within tolerance.
If deep cracks have de-
veloped, replace drum
immediately
This problem is signified by a bluish color
and disfigurement of the brake parts.
Heat Checking
Mishandling (new drum).
Excessive heating and
cooling.
Brake balance.
Driver abuse.
Replace brake drum.
Check to see if drum is
adequate for the applica-
tion.
Check for pneumatic or
torque balance problems.
Driver training
Replace cracked drums
immediately.
Upon inspection, the drum is found to have
cracked all the way through the entire wall.
Cracked Drums
Excessive heat from
dragging brakes or brake
imbalance.
Swollen linings.
Look for weak or broken
return springs or binding
brake actuation.
Consult lining manufac-
turer.
Drum can be used if
deep cracks are not pres-
ent.
Blue Drums
This problem is signified by a bluish color
and disfigurement of the brake part.
Problem
Probable Causes Recommended
Actions
TMC RP 608A © 2003 – TMC/ATA – Reprinted with Permission