Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Do"

Doble: A vehicle brand of which the 1925-1948 models are Classic cars.

DOC

Acronym for Double overhead camshaft
Acronym for Diesel Oxidation Catalyst

Dock: See
Dry dock

Docket: A formal record of a Federal Energy Regulatory Commission proceeding. These records are available for inspection and copying by the public. Each individual case proceeding is identified by an assigned number.

Doctor test: A qualitative method of detecting undesirable sulfur compounds (i.e., H₂S) in petroleum distillates, that is, of determining whether oil is Sour or Sweet.

Document: See
Registration document
Vehicle registration document

DOD: Acronym for the U.S. Department of Defense

Dodge: Click image for books on
Dodge

A vehicle brand of which the 1967-70 Coronet R/T models are Milestone cars Models include 100 Pickup (19__-89), 150 Pickup (19__-93), 250 Pickup (19__-93), 350 Pickup (19__-93), 600 (1984-88), Aries America (1981-89), Avenger (1995-2008), Caliber (2007-08), Caravan (1984-2007), Colt (1970-94), Colt Vista (1983-91), Dakota (1987-2008), Avenger (2007-present), Caliber (2007-present), Caravan (1984-2007), Challenger (2008-present), Charger (2006-present), Dakota (1987-present), Daytona (1984-93), Diplomat (1977-89), Durango (1998-present), Dynasty (1988-93), Grand Caravan (1987-present), Intrepid (1993-2004), Journey (2009-present), Lancer (1955-59, 61-62, 85-89), Magnum (2005-2008), Mini Ram Van (19-__-88), Monaco (1990-92), Neon (1995-2006), Nitro (2007-present), Omni America (1978-90), Raider (1987-89), Ram (1981-present), Ram 50 Pickup (19__-93), Ram 1500 Pickup (1994-2008), Ram 2500 Pickup (1994-2008), Ram 3500 Pickup (1994-2008), Ramcharger (1974-93), Ram Van (1971-2003), Ram Wagon (19__-2002), Shadow (1987-94), Spirit (1989-1995), Sprinter (2003-present), Stealth (1991-96), Stratus (1995-2006), and Viper (1992-present)

DOE: Acronym for U.S. Department of Energy -- the agency responsible for regulating energy sources including gas

Dog

Man's best friend.
A vehicle in very bad shape, which may not be man's best friend.
A lug or protrusion on an object.

Also see
Bird Dog

Dog clutch

A simple coupling with two halves called dogs, with square projections in one that engage in square slots in the other to transmit drive, but can also be disengaged to break the drive.
Mating collars, flanges, or lugs which can be moved as desired to engage or disengage similar collars, flanges, or lugs in order to transmit rotary motion

Dog guard: A grid made of tubular bars or wire mesh to keep a dog in the back part of a vehicle

Dogleg pillar: The C-post or C-pillar.

Dogleg section: An irregular shaped part of the leading edge of the rear quarter panel of a four-door sedan along the wheel cutout and up to the waistline

Dog Point: A cylindrical extension, or pilot, of diameter smaller than the minor diameter of the thread, commonly equal to about D/2 in length, with a conical section between it and the thread; usually used as a pilot in assembling or as the end of a set screw projecting into a fairly deep hole or slot.
Also see
Half dog point

DOHC

DOHC

Acronym for double-overhead camshaft. Refers to an engine with two overhead camshafts.
Acronym for Dual Overhead Cam

Also see
Double overhead cam
Engine type

Do it to it: Trucker slang for Speed up as in "Now that we're on the boulevard lets do it to it."

Do-it-yourself market: (DIY) The vehicle maintenance and repairs conducted by the vehicle owner or friend/relative who purchase auto parts from a retail outlet.

Do-it-yourself mechanic: A person, whether qualified or not, who does his own repairs on his own vehicle.

DOL: Acronym for Data Output Line to IPC

Dolly

A metalworking tool, available in a variety of shapes and sizes, comprising a curved polished block of cast iron or forged steel, used to assist in forming three-dimensional shapes and in straightening dented panels, usually by holding the dolly behind the metal to be shaped and hammering the metal.
A small two-wheeled trolley for moving heavy objects.
A trolley that supports the front wheels or back wheels of a disabled vehicle for towing it.
A Converter dolly

Also See
Grid dolly
Heel dolly
High Crown Dolly
Low Crown Dolly
Mushroom-shaped dolly
Roughing Dolly
Shrinking dolly
Toe dolly
Wheel dolly

Domains: Groups of atoms that have same magnetic polarity

Dome: See
Pop-up
Piston dome

Dome-hat: Sealed metal container for the motor compressor of a refrigerating unit.

Dome lamp: A dome-shaped interior light. Also called a dome light.

Dome light: A dome-shaped interior light. Also called a dome light.

Domestic: A vehicle produced in Canada, United States, or Mexico. The opposite is foreign.

Domestic Fuel: As defined by the Energy Policy Act, Section 301, domestic fuel is derived from resources within the United States, its possessions and commonwealths, and Canada and Mexico (the two nations in a free-trade agreement with the U.S.).

Domestic vehicle producer: An original vehicle manufacturer that assembles vehicles in North America (U.S.A, Canada, or Mexico) for domestic use.

Donor car: A car from which parts are used to repair another one of the same type or to build a special or kit car

Do not enter: Do not enter

A sign indicating that travel is not permitted down a certain road or in that direction

Donut: See
Exhaust Donuts

Door: The hinged side Panels of a vehicle which permit the occupants to enter or leave the passenger compartment. In most cases the doors open so that the hinge is toward the front of the vehicle. When the hinge is toward the back of the vehicle, they are called Suicide doors.

Also See
Barn Door
Filler door
Five-door
Four-door
Front Door
Gull-wing door
Mode Door
Pull-out door handle
Rear-hinged door
Sagging door
Suicide doors
Three-door
Two-door

Door alignment: Accuracy or fitting of the door in the door aperture

Door aperture: Opening into which the door fits

Door beam: A longitudinal reinforcing bar which fits between the inner and outer shell of the door. It is designed to withstand side impacts. Also called a side impact bar.

Door bottom: The lower door area, both of the door skin and of the door frame, also the narrow horizontal lower panel of the door frame that has the drain holes

Door capping: The molding between the door trim panel and the window glass

Door check arm: A metal part near the hinge which has several notches which allows the door to remain partially or fully open

Door check strap: A leather strap near the hinge which prevents the door from opening too far.

Door face: The edges of a door which are not visible from the outside or inside when the door is shut. Also called door shut.

Door frame

The bare skeleton of the door to which the door skin and door trim are added.
The door aperture.

Door gap: The distance around the door between the edge of the door and the aperture

Door garnish molding: A trim molding located on the door panel along the edge of the window opening.

Door glass: The glass pane filling the top half of a door, which can usually be lowered or raised

Door handle: The interior or exterior handle for opening a door.

Also see
Pull-out door handle

Door hinge: The pivoting part which is attached to the door fram and the door pillar. It allows the door to swing open or shut.

Door hold-open spring: A spring attached to the door hinge to provide a spring load to keep the door in an open position

Door latch: That part of the door lock which contacts the striker plate as the door is closed, and springs back when the door is fully shut to hold it in the closed position

Door lock: A mechanism for allowing a door to be opened either by the operation of a key on the outside of the door or by releasing a mechanical switch on the inside of the door.

Door lock de-icer: A fluid which is inserted into the key-hole to melt the ice which has bound the tumblers in a door lock.

Door mirror: An exterior, door mounted, rear-view mirror. On trucks and older vehicles the mirror is manually adjusted; but on many cars they are adjuste either by a cable inside the cab or by an electric motor with the switch inside the cab. The control device is located on the door, on the dash, or on the console between the driver and passenger.

Door pad: The door inner trim panel

Door panel: A panel covered in vinyl or other material and mounted to the inside of the door

Door pillar: One of the vertical members of the body shell ahead of and behind the doors, which also support the roof structure and reinforce the body as a whole

Door pillar switch: A small switch, typically in the lower portion of the A-pillar, whose main function is to turn on the courtesy lights when the door is opened and to indicate that the door is open especially if the key is left in the door.

Door pocket: A container or pouch located on the lower inside portion of the door. It can be used to store maps and other small items

Door post: One of the vertical members of the body shell ahead of and behind the doors, which also support the roof structure and reinforce the body as a whole

Door protector: A strip of rubber, plastic, or chrome which fits over the edge of the door to protect it from damage when opened carelessly

Door pull: A handle on the inside of a vehicle door which allows the driver/passenger to pull his door shut

Door rates: The hourly rates charged by dealers on standardized units of service work. Hourly rates may or may not correspond to an actual hour of work.

Door seal: A weatherstrip surrounding the door to form a seal when the door is closed

Door shut: The edges of a door which are not visible from the outside or inside when the door is shut. Also called door face.

Door sill: The bottom part of the door frame (i.e., the pat under the door when it is closed).

Door skin: The large sheet metal panel of the door visible from the outside. Available to body shops as a replacement panel for most cars

Door speaker: Radio/stereo speakers mounted in the door panel

Door stay: A device incorporated in door hinges that keeps the door in an open position and prevents it from closing under its own weight

Door step: Top part of the outer sill, visible when the door is opened

Door surround: The faces of the door step, door pillars, and roof section which makes up the door aperture

Door trim: A panel covered in vinyl or other material and mounted to the inside of the door

Door trim pad: The covering used to conceal the lower portion of the inside panel of the door.

Door well: A cavity enclosed by the door frame, door skin, and trim panel containing the window winding mechanism and into which the window glass is lowered

Doosy: See
Duesy.

Dope: Highly combustible alcohol/methanol-based fuel mixture

Dorris: A vehicle brand of which the 1925-1948 models are Classic cars.

Dos-a-dos: Back to back seating on older cars where the Driver and front passenger faced forward; but the two rear passengers faced rearward.

Dosimeter: See
Noise Dosimeter

DOT

Acronym for the U.S. Department of Transportation—an American federal agency
Acronym of Department of Transport—a British agency

DOT 3: This Brake fluid has a glycol base. It is clear or light amber in color. Its Dry boiling point is 205°C minimum and Wet boiling point of 140°C minimum. It will absorb 1 to 2 percent of water per year depending on climate and operating conditions. It is used in most domestic cars and light trucks in normal driving. It does not require cleaning the system and it can be mixed with DOT 4 and DOT 5.1 without damage to the system. The problem with it is that it absorbs moisture out of the air and thereby reduces its Boiling point. It can also damage the paint on a vehicle.

DOT 4: This Brake fluid has a borate ester base. It is clear or light amber in color. Its Dry boiling point is 230°C minimum and Wet boiling point of 155°C minimum. It is used in many European cars; also for vehicles in high-altitude, towing, or high-Speed braking situations, or ABS systems. It does not require cleaning the system and it can be mixed with DOT 3 without damage to the system. The problem with it is that it absorbs moisture out of the air and thereby reduces its Boiling point. It can also damage the paint on a vehicle.

DOT 5: This Brake fluid generally has a silicone base. It is violet in color. Its Dry boiling point is 260°C minimum and has no Wet boiling point in federal DOT 5 Specifications. It is used in heavy brake applications, and good for weekend, antique, or collector cars that sit for long periods and are never driven far. It does not mix with DOT 3, DOT 4, or DOT 5.1. It will not absorb water and will not damage the paint on a vehicle. It is also compatible with most rubber formulations. The problem with it is that it may easily get air bubbles into the system which are nearly impossible to remove, giving poor pedal feel. It is unsuitable for racing due to compressibility under high temperatures. If as little as one drop of water enters the fluid, severe localized corrosion, freezing, or Gassing may occur. This can happen because water is heavier and not mixable with silicone fluids. It is unsuitable for ABS.

DOT 5.1: This Brake fluid has a borate ester base. It is clear or light amber in color. Its Dry boiling point is 260°C minimum and Wet boiling point of 180°C minimum. It is used in severe-duty vehicles such as fleets and delivery trucks; towing vehicles, and race cars. It can be mixed with DOT 3 or DOT 4 without damage to the system. It maintains higher Boiling point than DOT 3 or DOT 4 fluids due to its higher borate ester content. It is excellent for severe duty applications. The problem with it is that it costs more than other fluids and there is limited availability. It also absorbs moisture out of the air and thereby reduces its Boiling point. It can also damage the paint on a vehicle.

DOT number: The symbol DOT on a tire means it meets or exceeds Department of Transportation safety standards. Following DOT are a maximum of eleven numbers. E.g., DOT FT TW A2NX 092. (DOT = meets or exceeds federal standards; FT = identifies manufacturing plant; TW = the code for tire size; A2N or A2NX-3 or optional four digits = manufacturer's code to identify the characteristics of the tire; 092 = Week of mfg., in this case, 9th week of 1972. Prior to May 22, 1971 the manufacturer's plant was identified by only three numbers (Example DOT 129). Retreaded tires must also have a new serial number and can be determined by the letter R following DOT letters.

Double A-arm suspension: Double A-arm suspension

A suspension system which has two triangular (A-shaped) control arms as the main support of the wheel. The wide ends of both upper and lower A-arms are hinged to the frame. The narrow ends are attached to the upper and lower ball joints. The steering knuckle (including the stub axle or spindle that carries the wheel bearing and the wheel) is fixed between these ball joints. This configuration allows the wheel to move up and down with variations in the road surface and left and right as it is steered, while keeping the wheel in the correct position with respect to the road and the vehicle. A spring and a shock absorber are set between the frame and the lower A-arm (shown in image), or between the frame and the upper A-arm, to absorb road shock and to help control wheel movements.

Double-acting: (of a shock absorber or pump) having a piston with fluid on both sides so that in a pump one piston end performs the suction stroke while the other discharges the liquid, and in a shock absorber both upward and downward movements are damped

Double Cab: Toyota's term for a Crew cab

Double anchor drum brake: See
Leading/trailing drum brake

Double-barrel carburetor: Two Throttle openings or barrels from the Carburetor to the Intake manifold. Also called twin-choke carburetor.

Also See
Four-barrel carburetor
Single-barrel carburetor

Double bottom: Compartments at the bottom of a ship between inner bottom and the shell plating, used for fresh water, ballast water, fuel oil, etc

Double cap nut: (Budd mounting) A type of securing device which consists of an inner cap nut (sleeve nut) and an outer cap nut. It is the most common method for mounting disc wheels in dual.

Double century: A bicycle ride of 200 miles (321.9 km).

Double clutch: See
Double clutching.

Double clutching: Vehicles with Manual transmission and no Synchromesh have difficulty shifting from one gear to another. With synchromesh, shifting is accomplished by depressing the Clutch pedal and moving the Gearshift selector from one gear to the next. Without synchromesh, shifting is not smooth unless you double clutch. Here you depress the Clutch pedal shift to Neutral lift up on the Clutch pedal blip the Throttle (Accelerator), then depress the Clutch pedal again and shift to the next gear. While this action seems complicated, you can get used to doing it to avoid the grinding noise heard in non-synchromesh transmissions.

Double coat: Two single coats of primer or paint applied with little or no flash time between them.

Also see
Single coat

Double-cradle frame: A motorcycle frame with two steel tubes circling the engine from the front and cradling it

Double-decker: A passenger bus with a set of seats on a floor above a lower set.

Double-decker bus: A passenger bus with a set of seats on a floor above a lower set.

Double-declutch: A British term for Double clutch

Double duty case: Commercial refrigerator in which a part of space is for refrigerated storage and part is equipped with glass windows for display purposes.

Double-ended spanner: British term for Double-ended wrench

Double-ended wrench: A tool which has a hexagon ring at each end.

Double End Stud: Threaded at both ends with standard Class 2A threads to take nut assembly.

Double filament bulb: A light bulb with two filaments. For example a headlamp bulb with one for the high beam and another for the low beam; or a bulb with one filament for the stop light and another for the taillight.

Double flare

The end of the tubing, especially brake tubing, has a Flare made so that the flare area uses two wall thicknesses. This makes a much stronger and safer Joint in bicycle tubing.
A flare used on the ends of brake lines for extra strength. The tubing flared end is doubled over.

Double harley: Trucker slang for Putting the CB on channel 11 as in "Anyone looking to buy a good C.B. take it to the double harley."

Double helical gear: A gear with two rows of inclined teeth, each forming an open V or chevron. Also called herringbone gear

Double hexagon socket: A socket with 12 points rather than the normal 6 points.

Double-leading brake: A non-servo brake in which both shoes are energized.

Double leading brake shoe: A system of braking where two hydraulic plungers and separate pivots create better braking when the vehicle is going forward; however it is not very effective when the vehicle goes in reverse.

Also See
Single leading brake shoe

Double nickel: Trucker slang for Traveling at 55 MPH as in "I sure got tired of running the double nickle."

Double overhead cam: Click to supersize
Double Overhead Cam

(DOHC) An engine with two Camshafts located above the Cylinders. One drives the Intake valves and the other operates the Exhaust valve. In a single overhead cam engine (SOHC), one cam has enough lobes to drive both the Intake and Exhaust valves. The DOHC engine is considered to be a very sophisticated and more efficient engine; but is sometimes more difficult to adjust the valves. Also called twin overhead camshaft.

Also See
Engine type.

Double overhead camshaft: See
Double overhead cam

Double-pivot steering: Steering in which the steered wheels are pivoted on kingpins, which is the usual arrangement on motor vehicles.

Also see
Ackermann steering
Single-pivot steering

Double reduction axle: A drive axle construction in which two sets of reduction gears are used for extreme reduction of gear ratio

Double reduction gearing: Gearing in which the ratio is reduced in two stages, used especially in heavy trucks

Double roller chain: See
Duplex chain

Doubles: Combination of a tractor and two semitrailers connected in tandem by a Converter dolly. Also called Twins or Twin Trailers

Double thickness flare: Copper, aluminum, or steel tubing end which has been formed into two-wall thickness, 37 to 45 deg. bell mouth or flare.

Double-throw switch single-pole: (SPDT) Electric switch with one blade and two contact points.

Double-trailing brake: A non-servo brake in which neither shoe is energized.

Double-tube shock absorber: An older design of hydraulic shock absorber using two concentric tubes, one serving as the working cylinder, the other as the reservoir.

Also see
Single-tube shock absorber

Double wishbone: A form of independent suspension used on the front of a vehicle where both the upper and lower wishbones are of equal length.

Double wishbone suspension: See
Double wishbone

Doughnut: See
Rubber doughnut coupling

Doughnut coupling: A flexible joint made of rubber and shaped like a ring doughnut. It is used, for example, between the front of the propeller shaft and the gearbox. Also called doughnut joint.
Also See
Rubber doughnut coupling

Doughnut joint: A flexible coupling made of rubber and shaped like a ring doughnut. It is used, for example, between the front of the propeller shaft and the gearbox. Also called doughnut coupling.

Dowel: A pin projecting from one of two mating surfaces which fits into a correspondng hole in the other thus lining up the two pieces accurately during assembly. Also called Locating dowel

Dowel pin

Dowel pin

A small cylinder (steel or wood) which is passed through or partly through two parts to provide proper Alignment and to prevent movement between them. Sometimes called locating pin.
Accurately dimensioned pin pressed into one assembly part and slipped into another assembly part to insure accurate alignment.

Dowel Screw: A fastener where both ends have gimlet points and is threaded similar to a lag bolt. The center section has a plain unthreaded shoulder. Used in joining two wooden members such as a leg to a table top.

Down: See
Bleed Down
Break Down
Change Down
Flag Down
Hammer Down
Laying The Bike Down
Pull It Down
Pump Down
Shift Down

Downdraft carburetor: A Carburetor in which the air passes downward through the Carburetor into the Intake manifold. Contrasts with Sidedraft carburetor.

Downdraught carburetor: British spelling for Downdraft carburetor

Downflow radiator: A traditional type of vertical radiator, with header tank and bottom tank and a system of small tubes and cooling fins in-between, the hot water entering at the top and exiting at the bottom. This type of radiator has been replaced by a crossflow radiator.

Downforce: A vertical force directed downward, produced by airflow around an object such as the body of a vehicle.

Downgearing: See
Downshifting.

Downhand welding: See
Flat position welding

Downhill bike: A bicycle designed for racing down mountains, features include long Travel (6 inches or more), dual suspension frame, great brakes, single chainring, long saddle, and a riser handlebar

Downlead: See
Antenna Downlead

Downpipe: The pipe that joins the entire Exhaust system to the Exhaust manifold.

Downshift: The act of selecting a lower gear. In Britain it is called downward change.

Also See
Forced downshift

Downshifting

Manually shifting to a lower gear in order to use the engine Compression to assist in reducing the vehicle's Speed especially when going down a steep hill. Also called downgearing.
Manually shifting to a lower gear in order to increase speed for overtaking another vehicle. Also called shifting to passing gear.

Downstroke

The downward movement of the piston, either the intake stroke or the power stroke in a four-cycle engine.
Trucker slang for A hill going down as in "You can put her in georgia overdrive on the downstroke."

Down Tester: See
Leak Down Tester

Downtime: Downtime occurs when a vehicle is being repaired (esp. a commercial vehicle), it cannot fulfil its function. There is a loss in both potential proceeds from its use as well as the salary of its operators.

Down tube: The bicycle frame tube running from the Headset to the Bottom bracket one part of the main triangle on a Bicycle Frame.

Down tube shifter: Down tube shifter

One of the gear shift levers mounted to the Down tube of a bicycle frame.

Downward change: A British expression of shifting the transmission to a lower gear. The North American term is Downshift.

Dozer: A portable frame straightening machine