Glossary “backlighting” Definition:
A technique used to make flat-panel displays easer to read
b
back seat
Glossary “back seat” Definition:
The position of a valve stem when turned to the left (ccw) as far as possible back seating a two-seat service valve on early AC compressors.
backfire
Glossary “backfire” Definition:
1). An explosion in the exhaust system. caused when an unburned air/fuel mixture is ignited, usually upon deceleration. 2). An explosion of the air/fuel mixture in the intake manifold, which is evident at the carburetor or throttle body and may be caused by improper ignition timing, crossed spark plug wires, or an intake valve that is stuck open. 3. The momentary recession of the flame into the welding tip, or cutting tip, followed by immediate reappearance or complete extinction of the flame.
backfire suppression valve
Glossary “backfire suppression valve” Definition:
An anti-backfire valve used in the air-injection system of an exhaust emission control. Allows additional air into the induction system whenever intake manifold vacuum increases.
backfiring
Glossary “backfiring” Definition:
1). The pre-explosion of an air/fuel mixture so that the explosion passes back around the opened intake valve, through the intake manifold, and out through the carburetor or throttle body. 2). The loud explosion of over-rich exhaust gas in the exhaust manifold that exits through the muffler and tailpipe.
backing plate
Glossary “backing plate” Definition:
Stamped steel plate upon which the wheel cylinder is mounted and the brake shoes are attached; a metal plate that serves as the foundation for the brake shoes and other drum brake hardware. Anchor pin is also attached to the backing plate.
backing stripe
Glossary “backing stripe” Definition:
Also reffered to as an insert, it is of the same metal as the base metal and can be placed behind the weld. It helps proper fit-up and supports the weld.
backlash
Glossary “backlash” Definition:
The clearance between the meshing teeth of two gears.
back flush
Glossary “back flush” Definition:
The use of a reverse flow of water, with or without a cleaning agent, to clean out the cooling system of a vehicle. Also used in other automotive systems that contain and transport some type of fluid, gases or liquid, but are flushed using other types of materials.
back pressure
Glossary “back pressure” Definition:
1). Resistance of an exhaust system to the passage of exhaust gases. This can have an adverse effect on performance, fuel economy, and emissions. Excessive back pressure may be caused by the clogged catalytic converter, or a dented or crimped pipe. 2). The excessive pressure buildup in an engine crankcase.
back pressure EGR
Glossary “back pressure EGR” Definition:
Some emissions-control systems use a back-pressure sensor or diaphragm to monitor back pressure so that exhaust gas recirculating flow can be increased when the engine is under maximum load, and producing maximum back pressure.
back pressure EGR valve
Glossary “back pressure EGR valve” Definition:
A back-pressure-dependent EGR valve. See the specific application; negative-back-pressure EGR valve or positive-back-pressure EGR valve, as applicable.
B-shim
Glossary “B-shim” Definition:
A valve spring adjuster with a 0.030 inch (0.76mm) used to balance spring pressure and to correct installed height.
babbitt
Glossary “babbitt” Definition:
An alloy used to line bearings made up of tin, antimony, copper, and other metals.
BAC
Glossary “BAC” Definition:
Bypass Air Control
B-cam
Glossary “B-cam” Definition:
A pattern used to grind pistons in an oval or cam shape with a 0.006 inch (0.152 mm) difference between the face and pinhole side.
B-circuit
Glossary “B-circuit” Definition:
Charging system with the regulator between the positive feed and the field coil.
B-pillar
Glossary “B-pillar” Definition:
The structural support just behind the front door.
B-post
Glossary “B-post” Definition:
A term often used for B-pillar.
B+
Glossary “B+” Definition:
Battery positive