DICTIONARY OF AUTOMOTIVE TERMS - "Bo"

Board

A printed circuit board.

Also See
Backing boards
Charging Board
Child Step Running Board
Dash board
Integrated Circuit Board
On board diagnostics
Printed circuit board
Running board
Shifting board
Skate Board

Board diagnostics

See
On board diagnostics

Board of Trade Unit

Obsolete unit of electrical energy, equal to one kilowatt-hour.

Boards

See
Backing boards

Board test

A test of a printed circuit board.

Boardwalk

Trucker slang for a bumpy road as in "I don't run 78 often cause it's a real boardwalk."

Boat chock

A cradle or support for a lifeboat.

Boat trailer

A trailer for carrying a boat.

BOB

Acronym for Break-out box

Bobbers

The custom bikes American riders built after WWII where the owners cut off, or "bobbed," much of the bodywork.

Bobbin

A flanged structure intended for the winding of a coil. Also called spool

Bobbin winding

A transformer winding in which all the turns are arranged on a bobbin instead of in the form of a disk. Generally used for the high-voltage windings of small transformers.

Bobtail

Bobtail truck

A term for a large truck without the trailer. Also refers to a Straight truck.

Bob-weight

A weight used to counterbalance some moving part of a machine.

Also See
Balance weight

Bodge

A British term to describe work that is done poorly or with defective materials.

Bodily harm

Physical injury to a person caused by an accident.

Bodily injury

Physical injury to a person caused by an accident.

Body

1. The main portion of an automobile. Often it refers just to the outside shell.
2. The main part of a housing.
3. The shank of a bolt.
4. In welding, it refers to the main structural part of a regulator.
5. A term used in describing the thickness or consistency (viscosity) of an adhesive, coating, or sealer

Also See
All-aluminum body
All-enveloping body
All-steel body
Black body
Carcass
Coachbuilt body
Distributor body
Dump body
Fabric body
Fiberglass body
Fully galvanized body
Half-round body file
Headlight body
Parallel middle body
Spark plug shell
Special body
Stressed body
Throttle body
Torpedo body
Unit body
Valve body

Body alignment shim

Body Shim

A flat piece of metal with a slot used to insert at a bolt location to move a body panel slightly into its proper place.

Body and frame

See
Integral body and frame construction

Body and frame construction

See
Integral body and frame construction

Body assembly

The building up of the automobile body from its various components.

Body builder

A person who builds automobile bodies, i.e., Coachbuilder.

Body-colored

Something that is painted the same color as the body.

Also See
Color-coded

Body component

Any structural part that makes up the body of a vehicle.

Body computer module

(BCM) Key element of self-diagnostic system used to control vehicle functions based on monitored inputs.

Body construction

The manufacturer of a vehicle body.

Body diameter

See Full body diameter

Body file

When patching hole in a body panel and filling it with body putty, a body file, which is a hand tool, is used for smoothing the putty to conform to the contour of the body.

Also See
Half-round body file

Body filler

A substance (often with the name Bondo) which is a paste used to fill minor imperfections in a body panel. It hardens and is shaped to fit. It can also be painted to match the rest of the vehicle.

Body flange

A point on the body where two panels overlap, forming a small step.

Body framing

An assembly of the body components.

Body fuel injection

See
Throttle body fuel injection

Body glass

The windshield, backlight (rear window), and side windows of a vehicle.

Body hammer

A hammer with a large flat pounding surface for removing dents.

Also see
Reverse curve panel hammer
Curved pein and finishing hammer
Shrinking hammer
Pick and finishing hammer
Planishing hammer

Body housing

See
Valve body housing

Body-in-white

In the process of building a vehicle, this is a body shell after everything is welded but before it is painted.

Body injection

See
Throttle body fuel injection

Body jack

A hydraulic tool for pushing or pulling body panels into shape.

Body lead

An alloy of lead and tin which is used to fill dents and seems in a body panel to establish a smooth surface. When heated it flows easily to fill the imperfections.

Body panel

The sheet metal that forms the outside body pieces.

Body plan

A drawing showing the forms of the various cross sections, the curvature of the deck lines at the side, and the projections, as straight lines of the waterlines, the buttock lines, transverse elevations and the diagonal lines.

Body putty

A malleable material designed to smooth on dented body areas, upon Hardening, the putty is dressed down and the area painted. Also called bondo.

Body rattle

A noise in the bodywork usually cased by loose parts, badly fitting doors, hood, or trunk lid.

Body repair

After a vehicle has suffered an accident or has corroded panels, the body needs to be repaired to bring it back to like-new condition.

Body roll

The rocking or tilting motion of a vehicle when it goes around the corner.

Body sealer

A tar-like substance which is used to seal body joints.

Body separator plate

See
Valve body separator plate

Body shell

The bare skeleton of a vehicle with all the wheels, doors, hood, trunk lid, etc. removed.

Body shop

A service outlet specializing in vehicle body repair work.

Body side molding

A protective stripe along each side of the vehicle running from the leading edge of the front fender, along the door panel(s) to the rear end of the back fender. It may be solid plastic or rubber attached directly to the panels while others are attached to a metal strip which in turn is attached to the panels.

Body spoon

A tool with a flat contoured working surface like a spoon. It is used to slap out dents and is sometimes used in place of a dolly when it is too difficult to reach behind the panel.

Body stripe

A decorative stripe applied to a motorcycle fuel tank or the outside of a car to enhance the appearance. Sometimes model names are also part of the stripes.

Body styling kit

An additional set of bolt-on parts (like spoilers, air dams, fender skirts, laker pipes, wings) which are intended to improve the looks, performance, and efficiency.

Body tub

The bare body shell (minus the doors, trunk lid, hood, fenders) which is lowered onto the chassis at the time of assembly.

Bodywork

The complete body structure mounted on the chassis of a vehicle with a separate chassis, and the complete sheet metal panel for unibody vehicles.

Bog

A Hesitation usually experienced when starting out.

Bogie

1. An assembly of four wheels on two axles with common suspension, usually on heavy commercial vehicles, trailers, and older Ski-Doos®
2. Assembly of two or more axles on a large truck, usually a pair in tandem
3. A small vehicle with a short wheelbase running on rails. Commonly used for the conveyance of coal or ore.
4. A British term for a four-wheel or six-wheel undercarriage of short wheelbase, which forms a pivoted support at one or both ends of a long rigid vehicle such as a locomotive or coach. Also called bogie truck. The US term is truck

Also spelled bogey

Bogie landing gear

A main landing gear carrying a pair or pairs of wheels in tandem and pivoted at the end of the shock strut or Oleo. This arrangement helps to spread the weight of an aircraft over a larger area and also allows the wheel size to be minimized for easier stowage after retraction.

Bogie truck

See Bogie

Bogie wheel

One of the suspension wheels on an older Ski-Doo®.

Bogey

See Bogie

Boil

The process of change from a liquid to a gas through the application of heat.

Boiler

1. Closed container in which a liquid may be heated and vaporized.
2. One of a wide range of pressure vessels in which water or other fluid is heated and then discharged, e.g., either as hot water for heating or as high-pressure steam for power generation.
3. A device for generating steam for power, processing, or heating purposes; or hot water for heating purposes or hot water supply. Heat from an external combustion source is transmitted to a fluid contained within the tubes found in the boiler shell. This fluid is delivered to an end-use at a desired pressure, temperature, and quality.

Also See
Babcock And Wilcox Boiler
Banked boiler
High-pressure Boiler
Hot Water And Low-pressure Steam Boiler

Boiler capacity

The weight of steam, usually expressed in kilograms or pounds per hour, which a boiler can evaporate when steaming at full load output.

Boiler compositions

Chemicals introduced into boiler feed-water to inhibit scale-formation and corrosion, or to prevent priming or foaming. Examples are sodium compounds (such as soda ash), organic matter and barium compounds.

Boiler covering

See
Lagging

Boiler crowns

The upper rounded places of a boiler of the shell type

Boiler efficiency

The ratio of the heat supplied by a boiler in heating and evaporating the feed-water to the heat supplied to the boiler in the fuel. It may vary from 60 to 90%.

Boiler feed-water

The water pumped into a boiler for conversion into steam, usually consisting of condensed exhaust steam and makeup fresh water treated to remove air and impurities.

Boiler fittings and mountings

See
Feed check valve
Pressure gauge
Safety valve
Stop valve
Water gauge

Boiler fuel

An energy source to produce heat that is transferred to the boiler vessel in order to generate steam or hot water. Fossil fuel is the primary energy source used to produce heat for boilers.

Boiler, high-pressure

See
High-pressure boiler

Boiler horsepower

Obsolete term for the equivalent of the heating capacity of 33,475 BTU/hr (9804 watts)

Boiler, hot water and low-pressure steam

A boiler furnishing hot water at pressures not more than 30 psi gauge (308 k_Pa) or steam at pressures not more than 15 psi gauge (205 k_Pa)

Boilermaker's hammer

Hammer with ball or straight and cross panes; used for caulking, fullering, and scaling boilers.

Boiler plate

Mild steel plate, generally produced by the open-hearth process; used mainly for the shells and drums of steam-boilers. Latterly steel with a higher yield stress is frequently specified.

Boiler pressure

The pressure at which steam is generated in a boiler. It may vary from little over atmospheric pressure for heating purposes, to 1500 lb-in ^-2 (10000 kNm ^-2 ) and over for high-pressure turbines.

Boiler scale

A hard coating, chiefly calcium sulfate, deposited on the surfaces of plates and tubes in contact with the water in a steam boiler. If excessive, it leads to overheating of the metal and ultimate failure.

Boiler setting

The supporting structure on which a boiler rests; usually of brick for land boilers and of steel for marine boilers.

Boiler stays

Screwed rods or tubes provided to support the flat surfaces of a boiler against the bursting effect of internal pressure.

Boiler test

1. A hydraulic-pressure test applied to check watertightness under pressure greater than the working pressure.
2. An efficiency test carried out to determine evaporative capacity and the magnitude of losses.

Boiler trial

An efficiency test of a steam boiler, in which the weight of feed water and of fuel burnt are measured, and various sources of loss assessed.

Boiling

The very rapid conversion of a liquid into vapor by the violent evolution of bubbles. It occurs when the temperature reaches such a value that the saturated vapor pressure of the liquid equals the pressure of the atmosphere.

Boiling point

(bp)

1. The exact temperature at which a liquid begins to boil or changes to a gas or vapor (i.e., Vaporizes). The boiling point of a liquid decreases with increasing altitude, and increases with pressurization. The Coolant in a modern Radiator/Coolant system can be as high as 127°C.
2. The temperature at which a liquid boils when exposed to the atmosphere. Since at the boiling point the saturated vapor pressure of a liquid equals the pressure of the atmosphere, the boiling point varies with pressure; it is usual, therefore, to state its value at the standard pressure of 101.325kNm^-2.
3. The temperature and pressure at which a liquid converts to a vapor. In physics, this point is defined as the temperature at which the vapor pressure of a liquid is equal to the pressure of the atmosphere on the liquid, which is equal to 100°C at sea level (101.3 kPa).

Also See
Dry boiling point
Equilibrium Reflux Boiling Point
Wet boiling point

Boiling temperature

Temperature at which a fluid changes from a liquid to a gas.

Also see
Boiling point

Boiling-water reactor

(BWR) Light water reactor in which the water is allowed to boil into steam which drives the turbines directly.

Bold-up

The application of retread or repair rubber.

Bollard

1. Any short upright post used to prevent vehicle access.
2. On a quay or vessel, a short post around which ropes are secured for purposes of mooring.

Bolometer

A device for measuring microwave or infrared energy, consisting of a temperature-dependent resistance used in a bridge circuit which gives an indication when incident energy heats the resistor. Used for indication when incident energy heats the resistor. Used for power measurement, standing-wave detectors and infrared search and guidance systems.

Bolster

1. A supporting brace.
2. The act of supporting.
3. A steel block which supports the lower part of the die in a pressing or punching machine.
4. The rocking steel frame by which the bogie supports the weight of a locomotive or other rolling stock (i.e., railway car).

Also See
Hexagonal bolster

Bolt

A securing device upon which a nut is threaded. It usually has a nut-type head. It is usually measured not so much by the size of the wrench required to secure the bolt; but by the diameter of the threads, the thread pitch, the length of the bolt under the head, and the strength of the bolt. A bolt is similar to a machine screw except that a bolt is usually secured with a wrench instead of a screwdriver.

Also See
Anchor bolt
Bent bolt
Big-end bolt
Binder bolt
Bridge bolts
Carriage bolt
Coach bolt
Countersunk bolt
Crankarm fixing bolt
Cylinder head bolt
Eccentric bolt
Elevator bolt
Fixing bolt
Flange bolt
Four bolt mains
Guide Bolts
Hex bolt
Hexagon bolt
Cam Bolt
Chainring Bolt
Crank Bolt
Crankarm Bolt
Queen Bolt
Seatpost Binder Bolt
hex head cap screw
lag bolt
Locking lug bolt
Lug bolt
Mounting bolt
Octagonal bolt
Octagonal head bolt
Pivot bolt
plow bolt
Round head bolt
Shear bolt
Stirrup bolt
threaded rod
Through bolt
U-bolt
Wheel bolt
Wheel lug bolt

Bolt and nut

A pair of objects with matching screw threads. When either the bolt or the nut is turned, it moves with great force. Often used as fixing devices. The nut is the circular piece that looks like a ring with threads on the inside hole. The bolt is the shaft with threads.

Also See
Pivot bolt

Bolt Blank

A headed rod or bar intended for a subsequent threading operation.

Bolt body

The blank portion of the bolt or screw which is between the thread and the head.

Bolt Circle Diameter

See
Chainring Bolt Circle Diameter

Bolt cutter

Bolt cutter

A tool for severing a bolt when normally unscrewing a nut from the bolt is impossible or time-consuming.

Bolt End

A headless rod threaded at one end and assembled with a square nut, designed to be welded or otherwise fastened to a part or structure.

Bolt hole

The hole in metal through which a bolt must be inserted or screwed in place.

Also See
Wheel bolt hole

Bolt hole circle

See
Wheel bolt hole circle

Bolt mains

See
Four bolt mains
Two Bolt Main

Bolt-making machine

A machine which forges bolts by forming a head on a round bar.

Bolt-on

Accessories which are easily secured to an automobile with just a few bolts rather than having to be welded in place. Usually done by the owner.

Bolt-on fender

A fender which is secured with bolts rather than being welded in place.

Bolt-on goodies

Accessories which are easily secured to an automobile, but are often for show rather than function.

Bolt-on kit

A group of parts available in one package which the owner can attach himself.

Bolt-on wing

British term for Bolt-on fender

Boltzmann equation

A fundamental diffusion equation based on particle conservation. The rate of losses, including leakage out of the region of interest and the rate of disappearance by reactions of all kinds, is equal to the rate of production from sources within the region and the rate of scattering into the region.

Boltzmann's constant

Fundamental physical constant given by k=R / N _A =1.3805 x 10 ^-23 JK ^-1 , where R is the ideal gas constant and N _A is Avogadro's number

Boltzmann's distribution

Statistical distribution of large numbers of small particles when subjected to thermal agitation and acted upon by electric, magnetic, or gravitational fields. In statistical equilibrium, the number of particles n per unit volume in any region is given by n=n ₀ exp(-E/k_T), where k is Boltzmann's constant, T is absolute temperature, E is the potential energy of a particle in given region, and n ₀ is the number per unit volume when E=0. Also called Boltzmann principle

Boltzmann's superposition principle

Principle that in a linear viscoelastic material, the accumulated viscoelastic creep strain resulting from a series of stress increments is the superposed sum of the creep responses to the individual increments.

Bomb

A vehicle which is in very poor shape, "The car is a bomb and not worth a nickel." In contrast, it can mean a vehicle which has great Acceleration, "The car flew down the track like a bomb." Atomic bomb

Bombardment

Process of directing a beam of neutrons or high-energy charged particles onto a target material in order to produce nuclear reactions.

Bomb calorimeter

An apparatus used for determining the calorific values of solid or liquid fuels. The bomb consists of a thick-walled, highly polished, steel vessel in which a weighed quantity of the fuel is electrically ignited in an atmosphere of compressed oxygen. The bomb is immersed in a known volume of water to which the combustion heat is transferred, and from the rise of temperature of which the calorific value is calculated.

Bomb sampler

Device for obtaining samples of dispersed particles at predetermined depths within a suspension, consisting of a closed cylindrical vessel with an automatic valve which opens when an extension tube hits the bottom of the suspension container. The sampler fills with suspension and then closes when the vessel is lifted.

Bond

1. A state of adhesion.
2. The act of connecting two components by means of a glue or adhesive or to cause them to adhere
3. The junction of the weld metal and the base metal
4. The grip exerted by one material on another.
5. The attachment between two surfaces that have been joined.
6. The adhesion between concrete and its reinforcing steel, due partly to the shrinkage of the concrete in setting and partly to the natural adhesion between the surface particles of steel and concrete.
7. Link between atoms, considered to be electrical and arising from the distribution of electrons around the nuclei of bonded atoms.

Also See
Chemical bond
Mechanical bond
Quarry Stone Bond
Quarter Bond

Bonded abrasive

A grinding part which is made of very hard particles which have been glued together to form a wheel, bar, rod, or cone used to wear down or smooth metal.

Bonded brake lining

Brake lining that is attached to the Brake shoe by an adhesive rather than by Rivets.

Bonded lining

1. Brake lining cemented to shoes or bands with high-temperature adhesive and cured under pressure and heat resulting in the elimination for the need for attaching rivets.
2. A lining which attaches to the Lining table or Backing plate with a high-temperature adhesive cured under heat and pressure.

Also see
Mold Bonded Linings

Bonded wire

Enamelled insulated wire coated with thin plastic; after forming a coil, it is heated by a current or in an oven or both for the plastic to set and the coil to attain a solid permanent form.

Bonding

1. The electrical interconnection of metallic parts of an aircraft normally at ground potential for the safe distribution of electrical charges and currents. Protects against charges due to precipitation, static and electrostatic induction due to lightning strikes. Reduces interference and provides a low-resistance electrical return path for current in ground-return systems.
2. Joining structural parts by adhesive. May be performed at high temperature and pressure.

   Also See
   Adhesive bonding
   Panel bonding

3. An electrical connection between adjacent lengths of armoring or across a joint.
4. The interactions between individual atoms and molecules.

   Also See
   Chemical bond

Bonding agent

1. A material which provides adhesion.
2. The cement used to secure Bonded linings to a brake shoe.

Bonding clip

A clip used in wiring systems to make connection between the grounded metal sheath of different parts of the wiring, in order to ensure continuity of the sheath

Bonding method

A procedure of joining two components with adhesive.

Bonding range

The time during which a satisfactory bond can be made. It is usually expressed in two numbers, the first number being the time in minutes one must wait after applying adhesive before trying to bond the surfaces, and the latter number being the longest drying period within which satisfactory bonds can be made, usually ten to 30 minutes after applying the adhesive.

Bond length

The minimum length of reinforcing bar required to be embedded in concrete to ensure that the bond develops the full stress in the bar.

Bondo

See
Body putty

Bond strength

1. The force or strength necessary to break a bond between two adhering surfaces or materials.
2. The intermolecular forces which hold matter together, particularly closely continguous surfaces of neighboring media, e.g., liquid in contact with a solid.

Also called Adhesion.

Bone

See
A bone
T-Bone
Backbone frame
Herringbone gears
Wishbone.

Boned

See
T-boned

Boning-in

A survey term describing the process of locating and driving in pegs so that they are in line and have their tops also in line; carried out by sighting between a near and a far peg previously set in the gradient desired.

Boning-rods

T-shaped rods used, in sets of three, to facilitate the process of Boning-in, two of the rods are held on the near and far pegs to establish a line of sight between them in the desired gradient, while the third is used to fix intermediate pegs in line.

Bonk

A term used to describe a condition experienced when running out of energy while riding a bicycle or running.

Bonnet

1. British term for vehicle Hood to cover the front engine bay.
2. A wire-netting cowl covering the top of a ventilating pipe or chimney.
3. A movable protecting cover or cap of the valve-box of a pump.
4. The cover plate of a valve chamber.
5. The hood of forge.
   

   Also See
   Auto bonnet

Bonnet badge

British term for Hood badge

Bonnet bump rubber

British term for Hood bump rubber

Bonnet bumper

British term for hood bumper or Hood bump rubber

Bonnet landing panel

British term for Hood landing panel

Bonnet liner

British term for Hood liner

Bonnet lock

British term for Hood lock

Bonnet pin

British term for Hood pin

Bonnet pin kit

British term for Hood pin kit

Bonnet release

British term for Hood release

Bonnet stay

British term for Hood rod

Bonnet support

British term for Hood rod

Bonnet tape

British term for Hood tape

Bonus

See
No-claims bonus

BOO

BOO Acronym for Brake On / Off Switch -- which warns the PCM that brakes are applied

Boogie

Trucker slang for top gear as in "I've got 'er up in the boogie now"

Book

See
Blue book
Paint chip book
Black Book
Red Book

Boom

1. Enhanced reverberation or resonance in an enclosed space at low frequencies.
2. A long beam such as the top and bottom members of a built up girder.
3. The main jib of a crane.
4. A spar holding the lower part of a fore-and-aft sail.
5. A spar attached to a yard to lengthen it
6. A barrier of logs to prevent the passage of a vessel.
7. A line of floating timbers used to form a floating harbor.
8. A pole marking a channel.
9. A length of flexible tubing to contain an oil spillage.
10. A long movable arm to carry a microphone or lamp above the action in film or television shooting.

Booming

1. A noise caused by interruptions to the flow of air such as an open windows.
2. Low pitched resonance, especially in the exhaust.
3. Thumping sound coming from large stereo woofers.

Boost

1. The amount of positive pressure created in an Intake system above normal Atmospheric pressure by a Turbocharger or Supercharger. Normal atmospheric pressure is 14.7 psi. A Blower providing 10 psi boost increases the pressure to 24.7 psi. Boost is sometimes measured in atmospheres where one atmosphere equals 14.7 psi. Thus 24.7 psi is about 1.7 atmospheres.

   Also See
   On boost
   Off-boost

2. The action of Jump starting one Battery from another.
3. To increase power, charge, or pressure, etc.; or to amplify volume, audio sound, etc.

   Also See
   Bass boost

Boost-activated ignition retard

On a turbocharged engine, a system which retards the ignition timing when the intake manifold is under pressure, in order to reduce the chance of detonation.

Boost control

A device regulating reciprocating-engine manifold pressure so that supercharged engines are not over-stressed at low altitude.

Boost-controlled deceleration device

(BCDD) A valve that, during deceleration, is triggered into action by high intake manifold vacuum the BCDD valve allows an additional source of air and fuel to enter the intake manifold during deceleration to obtain a more burnable mixture.

Boost control cut-out

See
Boost control override

Boost control override

In a supercharged piston aero-engine fitted with Boost control, a device (sometimes lightly wire-locked so that its emergency use can be detected), which allows the normal maximum manifold pressure to be exceeded. Also called boost control cut-out

Boost control valve

See
Blowoff valve

Booster

1. A radio device which amplifies the signal or the audio output to the speakers. Because of its size it is mounted in the glovebox, under the dash, in the center console, under the seat, or in the trunk.
2. A device incorporated in vehicle system (such as brakes and steering), to increase the pressure output or decrease amount of effort required to operate, or both.
3. A common term applied to the case of a compressor when used as the first stage in the cascade refrigerating system.
4. A rocket engine, or cluster of engines, forming part of a launch system, either the first stage or auxiliary stage, used to provide an initial thrust greater than the total lift-off weight. Also called booster rocket.

Also See
Air-suspended power booster
Battery booster
Brake booster
Electro-hydraulic Booster
Hydraulically Operated Power Booster
Hydraulic Booster
Hydraulic brake booster
Integral Vacuum Booster
Mechanical-hydraulic Booster
Multiplier Vacuum Booster
Power booster
Spring booster
Tandem Booster
Vacuum booster
Vacuum brake booster
Vacuum Suspended Power Booster

Booster amplifier

Amplifier used especially to compensate loss in mixers and volume-controls, so as to obviate reduction in signal-to-noise ratio.

Booster battery

A second battery used in commercial vehicles to give a little more power when starting.

Booster cable

See
Jumper cables

Booster coil

A secondary ignition coil which increases the intensity of the spark.

Booster fan

A fan for increasing the pressure of air or gas; used for restoring the pressure drop in transmission pipes, and for supplying air to furnaces

Booster holding position

The point at which a booster maintains a constant level of power assist

Booster pump

A pump which maintains positive pressure between the fuel tank and the engine, thus intensifying the flow. Any pump to increase the pressure of the liquid in some part of a pipe circuit.

Booster rocket

See
Booster

Booster station

Station which rebroadcasts a received transmission directly on the same wavelength

Booster transformer

A transformer connected in series with a circuit to raise or lower the voltage of the circuit.

Booster vacuum runout point

The point at which a Vacuum booster is supplying the maximum amount of power assist possible. Any additional braking force must be applied at the brake pedal.

Booster venturi

A small venturi located immediately above and concentric with the main venturi in a carburetor. Boosters are designed to amplify the weak venturi vacuum signal that occurs during low airflow conditions.

Boost gauge

1. An instrument or meter which indicates Boost pressure
2. An instrument for measuring the manifold pressure of a supercharged aero-engine in relation to ambient atmosphere or in absolute terms. Also used for racing and other car sports.

Boosting

See
Start boosting

Boost pressure

Pressure in the intake system of a supercharged engine when the supercharger operates. See the first definition of Boost.

Boost regulator

Voltage conversion device used to raise the voltage in a DC system.

Boost sensor

A sensing device in a supercharger. It is located in the choke tube which sends a signal to the ignition control unit according to pressure conditions. In turn, the control unit adjusts the ignition timing for the best performance.

Boost transformer

See
Buck transformer

Boost valve

A valve in a hydraulic system which increases the pressure.

Boot

1. British term for a Trunk.
2. The rubber or plastic Cover located at either end of the Spark plug cable to insulate the connections between the cable ends and the spark plug and Distributor terminal. Always grasp the cable by the boot when removing it.

   Also See
   Spark plug boot

3. A flexible rubber or plastic cover used over the open ends of the Master cylinder and Wheel cylinder to keep out water and other foreign matter
4. The protective Cover of the Ball joint that holds the Grease.
5. The cover that protects the suspension forks on a bicycle or motorcycle from dirt and grime.

   Also See
   Dust boot

6. A protective cover surrounding the Constant velocity joint

   Also See
   CV joint boot

7. A simple protective device (sometimes a piece of tube, tire, etc., cut to size) placed between the casing and tube. It offers temporary protection for the tube against pinching by an injury in the casing. It is not a repair of the injury and is unsafe to use.
8. A Denver boot, which is a device which clamps on the wheels of a parked car to immobilize it. Also called a Heavy yellow boot.
9. A colloquial term for the action of going very fast as in, We were booting along as fast as the snowmobile would go.
10. To accelerate rapidly as in, When the light turns green, boot it.

Also see
Denver Boot

Booted

A vehicle which has been disabled by a Denver boot is said to be booted.

Booted version

British term for Trunk model

Booth

See
Low-bake booth
Paint booth
Spray booth
Spraying Booth

Boot handle

British term for Trunk handle

Bootlid

British term for Trunk lid

Boot puller

See
Spark plug boot puller

Boots

See
Boot

Boot spoiler

British term for Trunk spoiler

Bootstrap

A self-sustaining system in liquid rocket engines by which the main propellants are transferred by a turbo-pump which is driven by hot gases. In turn the gas generator is fed by propellants from the pump.

Bootstrap circuit

A feedback circuit in which part of the output is fed back across the input giving effectively infinite input impedance and unity gain. Often used to improve the linearity of a voltage sweep generator.

Bootstrapping

The technique of using bootstrap feedback.

Also See
Bootstrap circuit

Boot tapping

The demarcation line between the two main colors of a ship's paintwork, at or near the water line.

Boral sheet

A composite made of boron carbide crystals dispersed in aluminum and also faced with aluminum. Used as a neutron absorber.

Border-pile

A pile driven to support the sides of a coffer-dam

Border shopping

See
Canadian cross border shopping

Bore

1. The area of a Cylinder hole through which a piston travels back and forth
2. The diameter or width of the cylinder.
3. The internal walls of the cylinder.
4. The circular hole along the axis of a pipe or machine part.
5. As a verb, it means to cut a circular hole.
6. With the word full it means to go fast.

Also See
Align bore
Full bore
Cylinder bore
Piston bore
Wheel center bore

Bored

To increase the diameter of the cylinder.

Also See
Stroked.

Bore diameter

The diameter of the Cylinders. It is usually measured in either inches or millimetres. When a Cylinder is bored out because of Scored Walls, it is increased by ten thou of an inch (0.01") or 0.25 mm.

Bore-stroke ratio

The relation between the diameter of the cylinder bore and the length of the stroke of the piston. If the stroke is longer than the cylinder bore diameter then the engine is called a Long stroke engine. If the stroke is shorter than the cylinder bore diameter then the engine is called a Short stroke engine. If the stroke is the same as the distance of the cylinder bore diameter then the engine is called a Square engine

Borgward

Click image for books on
Borgward

A German automobile manufacturer which began by Carl F. W. Borgward in 1921.

Boring

1. The process of machining a cylindrical hole, performed in a lathe, boring machine, or boring mill; for large holes, or when great accuracy is required, it is preferable to using a drill.
2. Renewing the Cylinders by cutting them out to a specified size, a Boring bar is used to make the cut.

Boring bar

1. A machine with a stiff bar that has multiple cutting bits used to cut engine Cylinders to a specific size. As used in garages, to cut worn Cylinders to a new diameter or bearing bores in proper alignment with each other.
2. A bar clamped to the saddle of a lathe or driven by the spindle of a Boring machine, and carrying the Boring tool.

Boring machine

A machine on which boring operations are performed, comprising a head, carrying a driving-spindle, and a table to support the work.

Boring mill

A vertical boring machine in which the boring bar is fixed, the work being carried by the rotating table.

Boring tool

The cutting tool used in boring operations. It is held in a Boring bar

Born-Oppenheimer approximation

An approximation used in considering the electronic behavior of molecules. The problems of the electronic and nuclear motion are treated separately.

Boron chamber

Counter tube containing boron fluoride, or boron-covered electrodes, for the detection and counting of low-velocity neutrons, which eject α-particles from the isotope boron-10. Also called boron counter.

Boron counter

See
Boron chamber

Borrow pit

Excavation which provides material to serve as fill when required.

Borsic

Boron fiber coated with silicon carbide

Bosh

The tapering portion of a Blast furnace, between the largest diameter (at the bottom of the stack) and the smaller diameter (at the top of the hearth).

Boson

A particle which obeys Bose-Einstein statistics but not the Pauli exclusion principle. Bosons have a total spin angular momentum of nh where n is an integer and h is Dirac's constant ( Planck's constant divided by 2π). Photons, alpha particles, and all nuclei having an even mass number are bosons.

Boss

Boss

An extension or strengthened section or projection (usually cylindrical) that holds the end of a pin or shaft. For example, the holes in the Piston through which the Piston pin is placed would easily break the thin walls of the piston when under pressure. The area around the hole (on the inner side of the piston) are strengthened to prevent breakage. This area is the Piston boss.

Also See
Brake boss
Gudgeon pin boss
Horn boss
Piston Boss

Bosses

The raised ledges or platforms on a Backing plate that support the brake shoes

Bossing mallet

A hammer with a pear-shaped wooden head used for shaping and stretching metal over a sandbag or wooden block.

Botch

1. A repair job which is very poorly done.
2. To do a repair job poorly.

Botched-up job

A colloquial term for a poor repair which will not be permanent.

Bottle

See
Acetylene bottle
Thermos Bottle

Bottle cage

Bottle cage

A water bottle holding bracket which is mounted to the frame of bike either with a clamp or by screws into a pair of braze-on nuts

Bottled gas

(LPG) Liquefied petroleum gas or Propane) gas compressed into strong metal portable tanks. The gas, when confined in the tank, under pressure, is in liquid form.

Bottle jack

Bottle jack

A hydraulic lifting device which is in the shape of a bottle

Bottleneck

A traffic situation where the road narrows to the point where traffic is excessively slowed.

Bottom

1. The lowest point. See Door bottom.
2. To lower something.
3. To reach the end of its travel (i.e., bottom out).
4. To make contact with the road.
5. One of the six Flavors of Quarks, with a mass of 4800 Me_V and a charge of -e/3. The bottomness of a bottom quark is 1, of an antibottom quark -1, and of all other particles 0. Bottomness is conserved in strong and electromagnetic interactions between particles but not in weak interactions. Also called beauty.
   

Also See
Door Bottom
Double bottom

Bottom bracket

Bottom bracket

Bicycle component that is inserted into the bottom bracket shell. The bottom bracket consists of the crank axle (bottom bracket spindle), ball bearings, and (in older style bottom brackets) a Fixed cup and an Adjustable cup. Crankarms are bolted to the bottom bracket.

Also See
Adjustable bottom bracket
Cartridge Bottom Bracket
Sealed bottom bracket
Splined bottom bracket
Square tapered bottom bracket

Bottom bracket shell

The barrel shaped portion of the frame into which the Bottom bracket is inserted. The seat tube, down tube, and chain stays are connected to the bottom bracket shell.

Bottom bracket spindle

The axle to which both of the crankarms are attached. The spindle length is measured in millimeters from one end of the spindle to the other.

Bottom dead center

(BDC) The lowest point of the Piston and Connecting rod travel in a Cylinder. In a horizontally opposed engine, it is sometimes called the Outer dead center. Opposite to Top dead center.

Also See
After bottom dead center
Before bottom dead center

Bottom dumps

Trailers that unload through bottom grates.

Bottom end

1. All the moving parts in the crankcase and their bearings.
2. The bottom part of the engine, where the crankshaft and usually the transmission resides
3. The lower range of engine revolutions.

Bottom end gasket kit

All the gaskets below the base gasket (crankcase gaskets and inspection cover gaskets) and all the O-rings and replaceable spacers in the bottom end of an engine.

Also See
Top end gasket kit.

Bottom gate

An Ingate leading from the Runner into the bottom of a mold.

Bottom gear

The lowest gear in a transmission.

Bottoming

1. A situation where the suspension reaches the end of its travel.
2. A situation where the lowest part of the chassis touches the ground, especially on a bump.
3. The lowest layer of foundation material for a road or other engineering works including structures.

Bottoming cycle

A waste-heat recovery boiler recaptures the unused energy and uses it to produce steam to drive a steam turbine generator to produce electricity.

Bottoming tap

Tapping threads in a blind hole

See
Plug tap

Bottom out

To reach the end of its travel.

Bottoms

1. A term used in connection with the Orford process for nickel and copper which have separated as sulfides. When the mixed sulfides are fused with sodium sulfide, the nickel sulfide separates to the bottom. Hence bottoms as distinct from tops.
2. In reverberatory furnace, the heavier molten material at the bottom of pool.

Bottom tank

In a thermosyphon water-cooling system, this is the bottom radiator tank.

Also See
Header tank
Radiator tank

Boucherot circuit

An arrangement of inductances and capacitances, whereby a constant-circuit supply is obtained from a constant-voltage circuit.

Bouchon

A hollow plug or bushing inserted in watch or clock plates to form the pivot holes.

Bouguer law of absorption

Law stating that the intensity p of a parallel beam of monochromatic radiation entering an absorbing medium is decreased at a constant rate by each infinitesimally thin layer db, i.e., -dp/p = kdb where k is a constant that depends on the nature of the medium and on the wavelength

Boulevard

Trucker slang for interstate highway as in "Once we hit the boulevard we can put some miles behind us."

Bounce

1. When referring to valves, it indicates a condition where the valve is not held tightly closed in the seat even though the Camshaft has not opened it. Also called Flutter or Valve bounce
2. When referring to a Distributor, it indicates a condition where the points make erratic contact when they should remain closed.
   

   Also See
   Contact bounce

3. When referring to Suspension, it indicates an up-and-down motion called Jounce and Rebound. You can test it by pushing down and releasing a corner of a vehicle.
4. The action of a vehicle dealer who increases the sale price of the vehicle, interest rate, monthly payments, etc.

Bouncing-pin detonation meter

An apparatus for determining quantitatively the degree of detonation occurring in the cylinder of a gasoline engine; used for fuel testing.

Boundary

See
Buffet boundary

Boundary film

A film of one constituent of an alloy surrounding the crystals of another.

Boundary layer

The thin layer of fluid (air) adjacent to the surface in which viscous forces exert a noticeable influence on the motion of the fluid and in which the transition between still air and the body's velocity occurs.

Boundary layer control

Modification of the airflow in the Boundary layer to increase lift and/or decrease drag by various means 1. removal of the boundary layer by sucking through slots or porous surfaces; 2. use of vortex generators to re-energize sluggish surface flow; 3. ejection of high-speed air through slits; and 4. blowing, by propulsion efflux, over wing surfaces.

Boundary layer noise

The noise occurring at high speeds due to the oscillations in the turbulent boundary layer at many frequencies and heard in cockpit and cabin.

Boundary lights

Lights defining the boundary of the landing area.

Boundary lubrication

A state of partial lubrication which may exist between two surfaces in the absence of a fluid oil film, due to the existence of adsorbed mono-molecular layers of lubricant on the surfaces.

Bound charge

The induced static charge which is bound by the presence of the charge of opposite polarity which induces it. Also, in a dielectric, the charge arising from polarization. Also called surface charge. Compare Free charge

Bound electron

See
Bound electrons

Bound electrons

Electrons in the inner orbits around the nucleus of the Atom, they are difficult to move out of orbit.

Bound state

Quantum mechanical state of a system in which the energy is discrete and the wavefunction is localized, e.g., that of an electron in an atom, where transitions between the bound states give rise to atomic spectral lines.

Bourdon gauge

See
Pressure gauge

Bourdon tube

A circular, hollow piece of thin metal tubing that is used in some instruments, pressure on the hollow section causes it to attempt to straighten, the free end then moves a Needle on the gauge face. Used in pressure gauges.

Bow

1. A sliding type of current collector, used on electric vehicles to collect the current from an overhead contact-wire. It consists of a bow-shaped contact strip, mounted on a hinged framework.
2. A flexible strip of whalebone or cane, the ends of which are drawn together to give tension to a thread or line which is given a single turn around a pulley of a pair of turns, drill, or mandrel. It is used as a sensitive drive for these tools and was used traditionally for the making of accurate holes, esp. for clock pivots.

Also See
Header bow
Hood bow
Main bow
Spring bow

Bow compasses

See
Spring bow

Bowden cable

A wire control cable within a metal or rubber sheath and used for activating a valve, clutch, choke, or accelerator.

Bowden gauge

Form of pressure-sensitive Transducer

Bowden-Thomson protective system

A form of protective system for feeders, in which special cables, with the cores surrounded by metallic sheaths, are employed; a fault causes current to flow in the sheath and operate a relay to trip the circuit.

Bowditch's rule

A rule for the adjustment of closed compass traverses, in which it may reasonably be assumed that angles and sides are equally liable to error in measurement. According to this rule, the correction in latitude (or departure) of any line = (Length of that line divided by Perimeter of traverse) times Total error in latitude (or departure)

Bowed

A bent shape.

Bowl

See
Carburetor Fuel Bowl
Float bowl

Bowl vent

(BV) Connects the float bowl to the carburetor's air inlet. Depressurizes the fuel being pumped into the float bowl by the fuel pump and acts as a vapor separator by allowing vapors in the float bowl to escape into the carburetor air inlet. Bowl vents are cut at a 45-deg angle and face incoming air so that reference pressure remains the same regardless of airflow.

Also see
Carburetor Fuel Bowl Vent
Internal Bowl Vent

Bowl vent port

(BVP) The port in the carburetor which vents fumes and excess pressure from the float bowl to maintain atmospheric pressure.

Bow nut

See
Wing nut

Bow propeller

A ship's propeller whose thrust can be directed at right angles to the ship's axis, used in docking and maneuvering in a confined space. Angular thrust can also be provided to the stern.

Bows

See
Spring bows

Bowser

A tanker used for refuelling military ground vehicles or airplanes.

Bowstring bridge

An arched bridge in which the horizontal thrust on the arch is taken by a horizontal tie joining the two ends of the arch.

Bowstring suspension

A form of suspension for the overhead contact-wire of an electric-tramway system, in which the contact-wire is suspended from a short cross-wire attached to the bracket-arm of the pole.

Bow thrusters

A propeller at the bow of the ship, used during maneuvering to provide transverse thrust.

Bow wave

The wave disturbance emanating from the leading edge of an object moving through fluid, esp. the V-shaped surface wave associated with boats moving through water.

Bow wow

A vehicle in very bad shape. A dog.

Bow-wow

A vehicle in very bad shape. A dog.

Box

1. Colloquial term for a Transmission.

   Also See
   Crash gearbox

2. A term for an electrical or electronic device.

   Also See
   Black box
   Balance box
   Break-out box
   Control box
   Crash recorder
   E-box
   Fuse box

3. A silencer.

Also See
Accumulator box
Balance Box
Black box
Cargo Box
CDI box
Crash box
Dry Box
Idiot Box
Junction Box
Panhard rod mounting box
Rocker box
Roof box
Slush box
Squirt box
Steering box
Tail light box

Box annealing

Heating to soften work-hardened material by placing the work in a sealed box inside the furnace in order to exclude air. Also called close annealing.

Box baffle

Box, with or without apertures and damping, one side fitted with an open diaphragm loudspeaker unit, generally coil-driven.

Box chronometer

The marine chronometer. The chronometer is normally supported on gimbals, inside a wooden box with a hinged lid.

Box culvert

A culvert having a rectangular opening.

Boxed rod

A Connecting rod in which the I-beam section has been stiffened by welding plates on each side of the rod.

Boxer

A two-cylinder engine with the pistons opposing each other, resembling fists flying away from each other.

Boxer engine

A Horizontally opposed engine.

Box-frame motor

A traction motor in which the frame is cast in one piece instead of being split

Box member

A structural part made as a Box section

Box nut

See
Cap nut

Box section

A closed panel structure of square cross section which is used to strengthen a vehicle's underbody.

Box Section Construction

A construction formed of two U-channels joined together to create a long box. It is used in frames where greater stength is required than is provided by a U-channel.

Box spanner

A British term for a hollow tube with a socket at each end and two holes through which a bar can be inserted to turn the wrench. The bar is called a T-bar; but the British call it a Tommy bar

Box tool

A single-point cutting tool, set radially or tangentially, used in automatic screw machines and in capstan and turret lathes.

Box-type brush-holder

See
Brush-box

Box van

A British term for a Cube van with a large cargo box behind the driver's cab.

Box wrench

A tool designed to secure or remove a bolt or nut. Each end of the wrench fits around the bolt head or nut. British term for ring spanner. In contrast, see Open end wrench.

Boxy

A derogatory description of a car that has square angles instead of smooth curved lines.

Boy

See
Low boy

Boyle's Law

Law of physics volume of a gas varies as pressure varies, if temperature remains the same. Example if absolute pressure is doubled on quantity of gas, volume is reduced one half. If volume becomes doubled, gas has its pressure reduced by half. Boyle temperature Temperature at which the second viral coefficient of a gas changes sign. Close to this temperature, Boyle's law provides a good approximation to the equation of state of the gas.

Boy racer

A low-cost car without much sophistication or performance; but it does have a very sleek and sporty appearance.

Boy's camera

A camera for photographing lightning flashes, gyrating lenses separating the strokes.

Boy scouts

Trucker slang for State police as in "There's a bunch of boyscouts waiting for you at the 157."