Automotive Glossary of Terms - B -
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Definitions for automotive terms and illustrations from backfire to busing.
BACKFIRE
The sudden combustion of gases in the intake or exhaust system that results in a loud explosion.
BACKLASH
The clearance or play between two parts, such as meshed gears.
BACKPRESSURE
Restrictions in the exhaust system that slow the exit of exhaust gases from the combustion chamber.
BAKELITE
A heat resistant, plastic insulator material commonly used in printed circuit boards and transistorized components.
BALL BEARING
A bearing made up of hardened inner and outer races between which hardened steel balls roll.
BALL JOINT
A ball and matching socket connecting suspension components (steering knuckle to lower control arms). It permits rotating movement in any direction between the components that are joined.
BALLAST RESISTOR
A resistor in the primary ignition circuit that lowers voltage after the engine is started to reduce wear on ignition components.
BATTERY
A direct current electrical storage unit, consisting of the basic active materials of lead and sulphuric acid, which converts chemical energy into electrical energy. Used to provide current for the operation of the starter as well as other equipment, such as the radio, lighting, etc.
BEAD
The portion of a tire that holds it on the rim.
BEARING
A friction reducing, supportive device usually located between a stationary part and a moving part.
BEFORE TOP DEAD CENTER (BTDC)
The point just before the piston reaches the top of its travel on the compression stroke.
BELTED TIRE
Tire construction similar to bias-ply tires, but using two or more layers of reinforced belts between body plies and the tread.
BEZEL
Piece of metal surrounding radio, headlights, gauges or similar components; sometimes used to hold the glass face of a gauge in the dash.
BIAS-PLY TIRE
Tire construction, using body ply reinforcing cords which run at alternating angles to the center line of the tread.
BI-METAL TEMPERATURE SENSOR
Any sensor or switch made of two dissimilar types of metal that bend when heated or cooled due to the different expansion rates of the alloys. These types of sensors usually function as an on/off switch.
BLOCK
BLOW-BY
Combustion gases, composed of water vapor and unburned fuel, that leak past the piston rings into the crankcase during normal engine operation. These gases are removed by the PCV system to prevent the buildup of harmful acids in the crankcase.
BOOK TIME
See Labor TimeBOOK VALUE
The average value of a car, widely used to determine trade-in and resale value.
BORE
Diameter of a cylinder.
BRAKE CALIPER
The housing that fits over the brake disc. The caliper holds the brake pads, which are pressed against the discs by the caliper pistons when the brake pedal is depressed.
BRAKE FADE
Loss of braking power, usually caused by excessive heat after repeated brake applications.
BRAKE HORSEPOWER
Usable horsepower of an engine measured at the crankshaft.
BRAKE PAD
A brake shoe and lining assembly used with disc brakes.
BRAKE PROPORTIONING VALVE
A valve on the master cylinder which restricts hydraulic brake pressure to the wheels to a specified amount, preventing wheel lock-up.
BRAKE SHOE
The backing for the brake lining. The term is, however, usually applied to the assembly of the brake backing and lining.
BREAKER POINTS
A set of points inside the distributor, operated by a cam, which make and break the ignition circuit.
BTDC
Before top dead center.
BUSHING
A liner, usually removable, for a bearing; an anti-friction liner used in place of a bearing.