User's Manual

209
UHB800-CAM
GLOSSARY OF TERMS
ABS: Anti-Lock Braking System
Actuator: A device which physically initiates the mechanical motion of a brake system component.
Air Disc Brakes (ADB): Air-actuated brakes, which upon application, employ a caliper to clamp two brake pads
against a rotor. Air discs, compared with drum-type brakes, have superior ability to resist fade.
AL Factor: A mathematical expression of the brake chamber and slack adjuster combination. “A” equals the
effective area, in square inches, of the brake chamber
diaphragm. “L” equals the effective length, in inches, of
the slack adjuster. For example, 30 (air chamber) x 6 (slack adjuster) = 180AL Factor.
Anchor Pin: A pin or pins inserted in the brake spider to which the brake shoes attach and pivot upon.
Anti-compounding: A system that prevents application of service brakes from compounding (adding) to the
force exerted by parking brakes. Functionally, this guards against brake drum cracking, brake shoe and brake
lining damage.
Anti-Lock: Optional on trailers until March 1, 1998, a safety oriented system which senses wheel rotation (at one
or more axles) during braking and cycles the brakes to prevent wheel lockup.
ASA: Automatic slack adjuster
ATA: American Trucking Association
ATC: Automatic traction control
BBW: Brake by wire
BCN: Brake certification notice
Bell-Mounted Drum: Drum with variation of inner diameter (i.e., greater at open end), preventing full contact
with brake linings.
Blue Drum: Brake drum with friction surface blued from high temperature. High temperature may result, for
example, from dragging of brakes caused by weak return springs. Blue drum also may result from lack of brake
balance.
Brake Block: Friction material or lining attached to brake shoe.
Brake Chamber Diaphragm: A device within the brake chamber that converts air pressure to mechanical force
via a push rod.
Brake Drag: Failure of one or more brakes to release immediately and/or completely after driver removes his
foot from the brake treadle. Constant drag, unrelated to a brake application, also can exist.
Brake Fade: Brake fade results from a reduction in friction between linings and drums caused by exposure to
water, dragging brakes on a down-grade or over-adjusted brakes resulting in an over-heated brake drum. Heat
fade occurs when linings overheat and become less aggressive. Gradual and predictable fade is desirable as a
warning. (Silver and Yellow will glaze if not burnished.)
Burnish: The conditioning or seasoning of a brake lining by wear and temperature via a test procedure or in-
service operation.