User's Manual

211
UHB800-CAM
GLOSSARY OF TERMS
FMVSS: Federal Motor Vehicle Safety Standard
Foundation Brake System: A term inclusive of mechanical components involved in mechanically providing
braking force: brake chambers, slack adjusters, brake drums, brake shoe assemblies.
FT: Fabricated, Tapered, Spicer’s term for brake design with a closed anchor pin rib. Interchanges with Rockwell
P design.
GAW: Gross axle weight
GAWR: Gross Axle Weight Rating, a rating in pounds of brake lining material, or axle carrying capacity.
GCW: Gross combination weight: the total weight carrying capacity of a combination vehicle as determined by
axle ratings.
GCWR: Gross combination weight rating
Grease-Stained Drum: A brake drum with discoloration of the friction surface caused by, for example, improper
greasing of brake camshaft.
GVW: Gross vehicle weight: the total weight carrying capacity of one vehicle, (such as a straight truck, bus,
tractor or trailer) as determined by axle ratings.
GVWR: Gross vehicle weight rating
HA: Suffix used to denote brake shoes used on axles produced by Spicer’s Heavy Axle & Brake Division.
HDBMC: Heavy Duty Brake Manufacturer’s Council
Heat-Checked Drums: A brake drum with a pattern of hard, slightly raised, dark spots on its friction surface.
Caused by localized overheating and sudden cooling. Those spots should be ground off to prevent drum crack-
ing, uneven lining wear and loss of braking efficiency. If spots cannot be removed, the drum should be discarded.
Lining Growth: Permanent swelling of brake linings due to heat exposure.
Lining Number : Numbers shown are FMSI (Friction Materials Standards Institute) standards and fit the
corresponding brake shoe core.
NHTSA: National Highway Transportation Safety Administration
Out-Of-Round Drum: A brake drum with variations in its inner diameter, causing reduced braking efficiency and
excessive wear on one side of the brake linings. An out-of-round drum often can be machined, within
manufacturer’s limits, to restore concentricity.
Over-Sized Drum: This refers to a brake drum having an inner diameter greater than the discard diameter
marked on the drum by its manufacturer.
P Brake: Rockwell’s term for brake design with a closed anchor pin rib. Interchanges with Spicer FT design.
PM: Preventive maintenance
Polished Drums: A brake drum with a friction surface polished to a mirror-like finish by unsuitable brake linings.
Remove gloss from drum with eighty grit emery cloth.