DICTIONARY OF AUTOMOTIVE TERMS - "De"

Dead:

See:
inner dead center
lower dead center
outer dead center

Dead axle:

An axle that does not rotate nor is driven but merely forms a base upon which to attach the wheels.
Also See:
beam axle. It contrasts with a live axle.

Dead battery:

A battery that registers almost no electrical charge. Sometimes it can be brought back to life with a charger. The British call it a "flat battery"

Dead center:

The point at which the piston reaches its uppermost or lowermost position in the cylinder the rod crankjournal would be at 11 o'clock UDC or 6 o'clock LDC.
Also See:
after bottom dead center
after top dead center
before bottom dead center
before top dead center
before upper dead center
bottom dead center
inner dead center
lower dead center
outer dead center
top dead center
upper dead center

Dead end:

A road which has no outlet

Dead freight factor:

The amount of a ship's carrying capacity that is not utilized.

Dead Head:

A cargo truck without its cargo that is being driven to a particular location

Dead-Heading:

Operating a truck without cargo.

Dead-head pressure:

A fuel pressure reading taken directly at the fuel pump outlet. Many systems use a fuel pressure regulator; dead-head pressure is an unregulated measurement

Dead pedal:

A footrest located to the far left of the driver so that he can brace his left leg during hard cornering or to balance the position of the right foot on the throttle pedal during normal driving.

Dead rear axle:

A rear axle that does not turn. E.g., rear axle of front wheel drive car

Dead rise:

Athwartship vertical rise between the keel and the bilge

Dead space:

The space below the piston availaable for pre-compression of the incoming fresh charge of the two-stroke engine.

Deadweight:

The total weight in tons (2240 lb.) that a ship carries on a specified draft including fuel, water in tanks, cargo, stores, passengers, baggage, crew and their effects, but excluding the water in the boilers. It is the difference in weight between a vessel when it is fully loaded and when it is empty measured by the water it displaces.
Also See:
tonnage deadweight

Dealer:

1. A firm that buys and sells, adding some value for the consumer in the process. Dealer often means a firm which operates closer in the distribution channel to the consumer than a distributor or wholesaler and may add more value for consumers than either of the above-mentioned terms. Also called "dealership."
2. A person whose business is buying and selling cars and trucks or motorcycles.

Also See:
authorized dealer
auto dealer
car dealer
franchised dealer
new car dealer
scrap dealer
used car dealer

Dealer invoice:

The price the dealer pays for a vehicle.

Dealer participation:

The amount contributed by the dealer to reduce the final purchase price in the lease contract. Dealer participation can take the form of a rebate or simply a discount. The dealer participation is reflected in the lease contract as a capitalized cost reduction.

Dealer principal:

The individual or corporation that owns and controls one or a number of auto dealerships.

Dealership:

A firm that buys and sells, adding some value for the consumer in the process. A dealership often means a firm which operates closer in the distribution channel to the consumer than a distributor or wholesaler and may add more value for consumers than either of the above-mentioned terms.

Deaeration:

Act of separating air from substances.

Death rattle:

An informal term for a noise from an engine which indicates that it is likely to break down at any moment

Debugging:

The process of locating and correcting faults in a system

Deburr:

To remove burrs from a metal surface

Deburring:

Removing burrs from a metal surface or bearing

Decal:

A sticker or transfer which is applied to a smooth surface to identify a particular product. Pronounced dee-KALL in the United States, but DECK-ull in Canada.

Decarbon:

The action of removing carbon buildup from the surface of the cylinder head and the dome of the piston. The accumulation of carbon indicates poor combustion and will result in loss of performance.

Decarbonize:

See:
decarbon

Decay:

A term for hydraulic pressure reduction that occurs during an ABS stop

Decelerate:

The action of slowing down. The opposite of accelerate

Deceleration:

Negative acceleration; the rate of change in velocity as a vehicle slows down during braking.

Deceleration fuel cut-off:

A device which stops the flow of fuel to the carburetor or injectors when the vehicle rapidly decelerates in the event of a crash thus preventing the possibility of a fire or explosion.

Deceleration switch:

A device that signals the rate of vehicle deceleration to the ECU, allowing it to adjust ABS operation accordingly

Decelerometer:

An instrument for measuring deceleration.

Decibel:

(dB) Unit used for measuring relative loudness of sounds. One decibel is equal to approximate difference of loudness ordinarily detectable by human ear, the range of which is about 130 decibels on scale beginning with one for faintest audible sound.

Deck:

1. The bed of a half-ton truck.
2. The floor of a commercial vehicle like a bus.
3. The trunk lid of a car. Also called "rear deck."
4. In an engine, top face of the cylinder block on which the cylinder head mounts.
5. Insulated horizontal partition between refrigerated space and evaporator space. Also called coil deck
6. A platform in a ship corresponding to a floor in a building.
   Also See:
   bulkhead deck
   freeboard deck
   main deck
   radio/cassette deck
   rear deck
   rear deck panel
   shelter deck
   strength deck
   tween deck
   weather deck

Deck beam:

An athwartship horizontal structural member supporting a flat or deck

Decker:

See:
double-decker

Deck house:

Small superstructure on the top deck which contains the steering wheel and other navigational instruments.

Decking:

See:
shaving

Deck lid:

The panel which covers the engine in a vehicle with the engine in the rear of the car.
Also See:
hood

Deck panel:

The sheet metal panel extending from the bottom of the rear window to the rear panel and enclosing the cutout for the trunk lid, extending sideways to the top of both rear fenders. In some cases, this panel covers only the area between the bottom of the rear window and the front edge of the trunk lid.
Also See:
rear deck panel

Deck ship:

See:
flush deck ship

Deck stringer:

The strake of deck plating that runs along the outboard edge of a deck

Declutch:

The action of disengaging the clutch (i.e. releasing the clutch pedal or lever).
Also See:
double-declutch

Decoke:

To decarbon

Decompressor:

A valve which is manually operated to release compression in a cylinder by allowing air to escape in order to facilitate manual starting of an old engine or a diesel engine. Some motorcycles also used a decompressor to assist in kick-starting.

Decreasing-radius corner:

A turn where the arc gets sharper as you progress through the curve

Dedicated:

Something that is designed for a specific use or for a specific vehicle.

De Dion axle:

A rear axle setup developed by Count de Dion in the 19th century in which the driving wheels are attached to curved dead axle that is attached to the frame by a central pivot, the differential unit is bolted to the frame and is connected to the driving wheels by drive axles using universal joints. The De Dion system keeps the wheels upright (the same as a live axle does), but unsprung weight is reduced because the differential is out of the axle. De Dion suspension also leaves room around the differential for inboard brakes, which can further reduce unsprung weight.

Deep cycling:

The process of discharging a battery almost completely before recharging

Deep tank:

Tanks extending from the bottom or inner bottom up to or higher than the lowest deck of a ship

Deer alert:

A device which is mounted on the outside of a vehicle and which makes a high-pitched sound to warn deer and other animals away. Whether it really works or not is debatable.

Defect:

A fault in a system or a flaw in materials or a finish

Defective:

A description of a component which is faulty or flawed.

Defensive driving:

A driving technique in which the driver prepares for and watches for the mistakes of other drivers around him so that he can avoid an accident.

Deflated:

An air chamber (like a tire or lumbar support chamber) which has lost all its air.

Deflation:

The loss of air from a tire or other air chamber

Deflation warning system:

(DWS) developed by Dunlop for on-line detection of tire pressure loss. When tire pressure is reduced, the tire circumference is also reduced resulting in increased wheel rpm. The system uses the wheel speed sensors of an existing ABS system to continuously monitor wheel speed and tire condition, and triggers a warning signal upon detecting a problem.

Deflection:

The movement of a suspension piece when subjected to a load.
Also See:
effective deflection

Deflection rate:

The distance that a spring squeezes together (deflects) in relation to the pressure applied. E.g., 5 inches per 1000 lb load.

Deflection under load:

See:
temperature of deflection under load

Deflector:

1. A device which causes bugs, tar, and grime from hitting other components.
2. A special piston profile used to achieve cross scavenging in earlier two-stroke engines.

Also See:
air deflector
air shield
bug deflector
stone deflector
wind deflector

Deflector piston:

A piston design which had a crown designed to direct the incoming fresh mixture upwards to expel the burnt exhaust gas from the cylinder. This design is no longer used today.

Deflector shield:

See:
sunroof deflector shield

Defog:

The action of removing mist or condensation from the inside of a window or the outside of a mirror by means of blowing air or heated wires imbedded in the glass. The British term is "demist."
Also See:
defogger.

Defogger:

An electric or hot air device to remove the fog or ice from both the inside and outside of the windshield, backlight (i.e., rear window) or even mirrors. Some are designed to remove fog from the side windows.

Defogging system:

See:
backlight defogging system

Deformation:

An alteration of shape or dimension which is caused by stress, expansion, or contraction because of temperature, humidity, or metallurgical changes.
also:
plastic deformation

Deformation zone:

A crumple zone

Defrost:

The action of removing frost from the inside of a window or the outside of a mirror by means of blowing air or heated wires imbedded in the glass.

Defrost cycle:

Refrigerating cycle in which evaporator frost and ice accumulation is melted.

Defroster:

The apparatus (either a fan connected to the heating system or electrical wires imbedded in the glass) which removes frost or fog from a window. Also called a "demister."

Defrosting:

Process of removing frost accumulation from evaporators.

Defrosting control:

Device to automatically defrost evaporator. It may operate by means of a clock, door cycling mechanism, or during "off" portion of refrigerating cycle.

Defrosting type evaporator:

Evaporator operating at such temperatures that ice and frost on surface melts off during part of operating cycle.

Defrost timer:

Device, connected into electrical circuit, which shuts unit off long enough to permit ice and frost accumulation on evaporator to melt.

Deglaze:

The action of removing the smooth finish on cylinder walls so that a new set of rings will seat.

Deglazer:

An abrasive tool used to remove the glaze from cylinder walls so that a new set of rings will seat.
Also See:
glaze breaker

Degradable:

See:
bio-degradable

Degradation:

The deterioration in the condition of something.
Also See:
catalyst degradation

Degrease:

1. To remove oil and grease from the surface of a parat.
2. Wiping the surface to be painted with a clean cloth saturated in a solvent. This is essential to good paint adhesion.

Degreaser:

A substance which removes dirt and grease from a mechanic's hands. Also called "hand cleaner."

Degreasing:

1. The removing of grease or oil from a surface.
2. Solution or solvent used to remove oil or grease from refrigerator parts.
   

Also See:
alkaline degreasing
vapor degreasing

Degreasing agent:

A solvent or alkaline solution which is used for removing oil and grease

Degree:

1/360 part of a circle.

Degree-day:

Unit that represents one degree of difference from inside temperature and the average outdoor temperature for one day; often used in estimating fuel requirements for a building.

Degree wheel:

A wheel-like disc divided into 360 equal parts that is attached to the engine crankshaft it is used to time the valves to a high degree of accuracy.

Dehumidifier:

A device which absorbs moisture from the atmosphere. It can be a unit dedicated for this purpose, or even an air conditioner.

Dehumidify:

To remove water vapor from the air

Dehydrated oil:

Lubricant which has had most of its water content removed (dry oil).

Dehydrator-receiver:

Small tank which serves as liquid refrigerant reservoir and which also contains a desiccant to remove moisture. Used on most automobile air conditioning installations.

Dehydrator:

See:
drier

De-ice:

To remove the ice from the outside of the windshield.

Deice control:

Device for operating a refrigerating system in such a way as to provide melting of the accumulated ice and frost.

De-icer:

A liquid or spray which is applied to the windshield to assist in removing ice.
Also See:
door lock de-icer
lock de-icer

De-ionized water:

Water from which impurities have been removed by a special process and used for topping up batteries.

Delage:

An old brand of automobile of which the 1925-1948 Model D-8 (but not the 4-cyl.) with required application is a classic car. The 1946-49 D-6 Sedans are milestone cars.

Delahaye:

An old brand of automobile of which the 1925-1948 Series 135, 145, 165 (but not the 4-cyl.) with required application are classic car. The Type 135, 175, 180 (1946-51) are milestone cars.

De-laminate:

To split a layered or laminated material into its separate layers. Sometimes used to describe failure of an adhesive in bond strength testing

Delaunay:

An old brand of automobile of which the 1925-1948 6-cyl Belleville are classic cars.

Delay:

See:
headlight on/off delay system
ignition delay

Delay relay:

See:
time delay relay

Delay system:

See:
headlight on/off delay system

Delay vacuum bypass system:

(DVB) an optional system used by Ford that bypasses the spark delay valve during cold operation to improve driveability

Delay valve:

A valve used in a vacuum or hydraulic system in which the valve's opening or closing is delayed. Also called vacuum delay valve

Delay wiper:

A windshield scraper which can be set to activate at various times and pauses between each swipe. It is useful when there is a mist or light rain. Also called "intermittent wiper."

D'elegance:

See:
concours.

D'elegance:

See:
concours d'elegance

Delineator post:

A barracade marking device placed on a road to prevent travel in a particular direction

Deliver:

1. To pump or discharge a liquid.
2. To drive a new car from the factory to the distributor or dealer. Or to drive it to the customer.

Delivery:

1. The discharging of a liquid from a pump.
2. Driving a new car from the factory to the distributor or dealer

Delivery lines:

Fuel lines used to carry fuel from the fuel injection pump to the injector nozzles

Delivery mileage only:

The odometer reading reflects only the distance from the factory to the selling dealer.

Delivery valve:

1. The valve on the outlet side of a pump.
2. A fuel injection pump valve that rapidly decreases injection line pressure to achieve an abrupt fuel cutoff at the injector

Delorean:

A model of automobile manufactured by John Z. DeLorean
Click image for books on Delorean

Del Sol:

A model of automobile manufactured by Honda
Click image for books on Honda Del Sol

Delta configuration:

A triangular connection of the three stator windings of an alternator.
Also See:
Y-configuration

Delta transformer:

Three-phase electrical transformer which has ends of each of three windings electrically connected to form a triangle.

Deluxe:

Abbreviated (DL). A term used to indicate a series of vehicle which is just above the basic version.

Delugger:

A machine used to cut the lugs from tires prior to buffing.

Demagnetize:

Removing residual magnetism from an object which had been previously magnetized

Demand meter:

Instrument which measures the kilowatt-hour usage of a circuit or group of circuits.

Demist:

A British term to clear fog or frost from the windshield or rear window. In the US and Canada, the term is defog.

Demister:

A British term for a defogger or defroster

Demonstrator:

A vehicle used by a dealer for test drives and sold later at a reduced price.
Also See:
ex-demonstrator

Demountable flange:

A side ring or side and lock ring combination that retains the tire on the rim. It is removable to permit tire mounting or removal.

Demountable rim:

A two piece wheel rim found on trucks. The main part of the rim remains on the axle while a side piece and a locking ring is removable. In this way the whole rim is not removed from the vehicle like a passenger car's rim and wheel. Demountable rims are still in use, though they have been replaced in many applications by the simpler disc wheel. Also called a "detachable rim"

Denatured alcohol:

Ethyl alcohol made unfit for drinking by the addition of toxic or nauseating substances such as methanol, benzene, or pyridine. Used to clean a brake system.

Denovo tire:

A special tire (fitted to a special rim) which used to be made by Dunlop, and which can be run flat for up to 160 km (100 miles) at up to 80 kph (50 mph)

Density:

1. Compactness; relative mass of matter in a given volume.
2. Closeness of texture or consistency of particles within a given substance. The weight per unit volume.
3. The weight or mass per unit volume of a gas, liquid, or solid

Dent:

1. A hollow or dip in a body panel caused by a sharp blow or impact.
2. To cause a dent in a body panel

Dent puller:

A tool with a strong suction cup to pull out dents in body panels.
Also See:
panel puller
suction cup dent puller

Denver boot:

A locking device which wraps around the wheel of a vehicle to immobilize its movement

Deodorizer:

Device which absorbs or adsorbs various odors, usually by principle of absorption. Activated charcoal is commonly used.

Départ:

The starting line of a randonnée or brevet

Departure angle:

The most sharply angled incline the vehicle can leave without its rear hitting the ground. As with approach angles, it's formed on one side by the horizontal axis, and on the other by a straight line connecting the rear edge of the rear tire and the most prominent point at the rear of the vehicle, usually the bumper or exhaust pipe.

Depolarize:

Removal of residual magnetism thereby destroying or removing the magnetic. To remove polarity

Deposit:

1. A coating of unwanted mineral or layer of sediment at the bottom of a tank.
2. To apply a coating of something (often metal by electrolysis).

Also See:
gum deposit
lead deposit
refundable deposit

Deposition:

See:
electrolytic deposition
vapor deposition
zinc vapor deposition

Depreciation:

The loss of value of a vehicle because of age or deterioration

Depression:

1. An indentation or dent in the surface of a sheet of metal whether through deliberate design or accident.
2. A restriction of airflow which causes low pressure and a partial vacuum.

Also See:
constant-depression
constant depression
engine depression
valve clearance depression

Depressor:

See:
valve spring depressor

Depress the accelerator:

The action of pressing down on the gas pedal (accelerator) to cause more fuel to enter the engine thus making the vehicle go faster. Opposite to "ease up on the accelerator."

Depress the gas pedal:

The action of pressing down on the gas pedal (accelerator) to cause more fuel to enter the engine thus making the vehicle go faster. Opposite to "ease up on the gas pedal."

Depress the throttle pedal:

The action of pressing down on the throttle pedal (accelerator) to cause more fuel to enter the engine thus making the vehicle go faster. Opposite to "ease up on the throttle pedal."

Depth:

See:
molded depth
profile depth
skid depth
throat depth
tread depth
well depth

Depth gauge:

A measuring tool for determining the depth of something.
Also See:
tread depth gauge

Depth micrometer:

A measuring device (micrometer) used for precise measurement of a hole depth, recesses, keyways, etc.

Depth of thread:

The distance from the thread crest to root measured perpendicular to the axis of the thread

Derailleur:

A lever-activated mechanism that pushes the chain off one sprocket of a bicycle and onto another, thus changing the gear ratio.
Also See:
front derailleur
rear derailleur.

Derailleur cable:

A wound steel cable running from the shift lever to the derailleur on a bicycle.

Derailleur cable housing:

The outer casing into which the inner wire is inserted. The inner wire of a brake cable and matching housing is thicker than those of a derailleur and thus are not compatible.

Derailleur chain, narrow width:

A bicycle chain made especially for use on an "ultra" or narrow freewheel often recognized by bulging inner link plates and flush chain pins.

Derailleur chain, standard width:

A bicycle chain designed to fit a freewheel of standard width, usually characterized by straight-edged plates and chain pins that protrude slightly beyond the outer link plates.

Derailleur hanger:

The part of a rear dropout to which the rear derailleur attaches

Derailleur pulleys:

One of two guide wheels of the rear derailleur which directs the path of the chain.

Derrick:

A device for hoisting and lowering heavy weights, cargo, stores, etc

Derust:

To remove rust from a metal part

Derv:

Diesel oil when used as a fuel for road vehicles. Acronym for "diesel-engined road vehicle"

Descaling:

The removal of scale or metallic oxide from metallic surfaces by pickling

Desiccant:

1. A drying agent (silica gel or a similar substance) used in refrigeration or air conditioning systems to remove excess moisture from refrigerant vapour
2. Substance used to collect and hold moisture in refrigerating system. A drying agent. Common desiccants are activated alumina and silica gel.

Design:

1. The arrangement of parts or the form of construction.
2. To arrange parts or construction of a vehicle or major component.

Also See:
cab-forward design
cabin-forward design
cam design
cam profile
component design
open-deck design
product design
wrapround dash design

Designation:

See:
model designation
one-piece rim designation
rim designation
type designation

Design pressure:

Highest or most severe pressure expected during operation. Sometimes used as the calculated operating pressure plus an allowance for safety.

Desmodromic:

Something (like valves) which is opened and closed by a mechanical device. In most 4-stroke engines the valves are opened by the cam, but closed by the action of the valve springs. In a desmodromic system, the valves are opened by a cam and closed by a cam or a cable. A desmodromic system is more costly and more difficult to manufacture, but the advantage is more precise control of the valves and less valve bounce which is seen in a normal engine at high speed.

Desorption:

The removal of material which has been adsorbed. It is the opposite of adsorption.

DeSoto:

A vehicle brand of which the 1956-58 Adventurer models are milestone cars.
Click image for books on DeSoto

Destruction:

Trucker slang for Road construction as in "Seem's like all the roads in pennsylvania are always under destruction."

Detachable rim:

A wheel rim which is bolted to the wheel center or spider and can be disassembled for replacing the rubber tire. It is found on trucks and some quads. It is also called a demountable rim

Detachment:

See:
flow detachment

Detail:

The action of correcting all appearance flaws in a vehicle.

Detailitis:

A term coined by Art Treta to indicate a compulsive disorder which compels a vehicle owner to correct its every flaw to the extent that he searches for even the most hidden flaw.
Also See:
restorationitis

Detector:

See:
glass tampering detector
radar detector

Detector, leak:

Device used to detect and locate refrigerant leaks.

Detent ball and spring:

A spring loaded ball that snaps into a groove or notch to hold some sliding object in position.

Detergent:

A soap-like chemical added to the engine oil (particularly MS oil) or gasoline to improve its characteristics and keep the engine clean by controlling the formation of sludge and gum as well as controlling foaming.

Detergent oil:

An MS oil which keeps the engine clean by preventing the formation of sludge and gum.

Deterioration:

See:
catalyst deterioration
thermal deterioration

DeTomasoPantera:

A model of automobile manufactured in Italy
Click image for books on Pantera

Detonation:

The action of the fuel charge firing or burning too violently, almost exploding. It sometimes results in a noise called "pinging." Detonation is caused by autoignition of the "end gas" i.e., that part of the charge not yet consumed in the normal flame-front reaction. Detonation occurs because piston motion and compression of the end gas raise its temperature and pressure to the point where the end gas autoignites. The pinging or knocking noise is the result of intense pressure waves in the charge which cause the cylinder walls to vibrate. Also called "fuel knock."

Detonation-activated ignition retard:

A system which retards the ignition timing when the detonation sensor picks up vibration at frequencies typical of denotation

Detonation sensor:

A sensor, usually piezoelectric, mounted near the cylinders which can detect engine knocking or frequencies of detonation so that it will send a message to retard the ignition timing to prevent damage to the engine.

Detour:

An alternative route which traffic has to follow due to closure of a stretch of road for repairs, etc. A diversion.

Detoxed vehicle:

A vehicle with a reduced emission system consisting of a catalytic converter, EGR, air injection, fuel evaporative emission control, etc. Also called a "controlled vehicle"

Detuned:

The intentional adjustment of an engine to reduce its power in an attempt to reduce emissions, reduce top-end speed, increase fuel economy, or meet specific governmental standards.

Deuce:

Hot rod built around a 1932 Ford coupe body.

Deutsche Industrie Normen:

See:
DIN.

Development:

See:
research & development

Deviation angle:

See:
tire deviation angle

Device:

A piece of equipment or a mechanism designed for a specific purpose or function.
Also See:
anti-roll device
antiroll device
economy device
electronic sensing device
enrichment device
sensing device
triggering device

DeVille:

A model of automobile manufactured by General Motors' Cadillac division
Click image for books on DeVille

Devon:

A vehicle brand of which the 1958-62 S/S models are milestone cars.

Dew:

Condensed atmospheric moisture deposited in small drops on cool surfaces.

Dewax:

To remove a coating of wax from the body of a vehicle usually in preparation for painting.

Dew point:

Temperature at which vapor (at 100 percent humidity) begins to condense and deposit as liquid.

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