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COMING
SOON: SKID CONTROL
SESSIONS.....WATCH OUT FOR DETAILS Official Driving School for The Civil Protection Department. Cell: 79693511 |
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D: [1] Abbreviation for "diesel." [2] Abbreviation for
"drive. [3] A mark on the output (live) terminal on a generator (contrasts
with "F")
damper piston: A piston in a cylinder whose movement is restricted by a liquid or gas, which thus also restricts the movement of another member to which it is connected. damper springs: springs in a clutch plate providing a cushion against sudden loads due to abrupt engagement damper strut: A suspension strut whose hub carrier is attached to the spring element rather than to the damper tube. Compare Macpherson strut damping: Cushioning of force. damping force: The amount of cushioning applied by a shock absorber damping rate: The amount of cushioning applied by a shock absorber Darracq: A vehicle manufacturer in which only the 8-cyl. cars and 4-litre, 6-cyl. cars of 1925-1948 are classic cars. dash: See dashboard. dashboard: That part of the body containing the driving instruments, switches, etc. Also called the "instrument panel" or "dash panel" or just "dash." dashboard gearchange: British term for dash shifter dashboard plaque: [1] A metal or plastic plate which is mounted to the dash to indicate the brand, model, or series of vehicle. [2] A metal plate which is mounted to the dash to indicate an award for attending or winning a rally or other automotive event. dash panel: [1] A structural panel with bracing across the width of the car on the inside of the bulkhead below the windshield that provides the mounting locations of the dashboard. [2] The bulkhead dash plaque: [1] A metal or plastic plate which is mounted to the dash to indicate the brand, model, or series of vehicle. [2] A metal plate which is mounted to the dash to indicate an award for attending or winning a rally or other automotive event. dashpot: A unit using a cylinder and piston, or a cylinder and diaphragm, with a small vent hole, to retard or slow down the movement of some part. dash shifter: A shift lever and indicator which is located on the instrument panel either as a short lever or push buttons day-night mirror: A mirror which adjusts to prevent the glare from the headlights of following cars. The British term is "dipping mirror." days' supply: number of days needed to sell all vehicles in inventory, based on the previous month's sales rate. daytime running lights: A safety-oriented lighting system in which the headlights or other front lights are constantly on even during the day. They help to prevent possible accidents because oncoming traffic can be seen. dazzle: The glare from the headlights of oncoming traffic which can momentarily blind a driver. dBA: A unit of measure for decibels, the measure of sound intensity or pressure named after Alexander Graham Bell. It is a logarithmic measurement; every 3dB increase represents a doubling of the sound pressure. The "A" in dBA indicates that the measurement was taken with an A-weighted scale; sound pressure varies across the audible spectrum, and the A-weighted scale approximates the human ear's sensitivity to various frequencies. DBI: Acronym for "De Danske Bilimport rer" (Denmark) dbl: Abbreviation for "double," as in dbl.-wide rear wheels. DC: [1] As an electrical term, it is an acronym for "direct current." [2] As a piston position, DC is an acronym for "dead center" where the piston at the extreme top or bottom of its stroke. DC generator: See generator DC rim: Abbreviation for Drop-Center rim
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 crank journal would be at 11 o'clock UDC or 6 o'clock LDC. 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 space: the space below the piston availaable for pre-compression of the incoming fresh charge of the two-stroke engine. 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. dealer invoice: The price the dealer pays for a vehicle. 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. 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 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 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. decelerometer: An instrument for measuring deceleration. 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 rests 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 abetween the bottom of the rear window and the front edge of the trunk lid deck lid: The panel which covers the engine in a vehicle with the engine in the rear of the car. Also see hood. declutch: The action of disengaging the clutch (i.e. releasing the clutch pedal or lever) 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. dedicated: Something that is designed for a specific use or for a specific vehicle.
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 deflection rate: The distance that a spring squeezes together (deflects) in relation to the pressure applied. E.g., 5 inches per 1000 lb 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 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. 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." 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, or even mirrors. Some are designed to remove fog from the side windows. deformation: An alteration of shape or dimension which is caused by stress, expansion, or contraction because of temperature, humidity, or metallurgical changes 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. 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." 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. degradation: The deterioration in the condition of something 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: The removing of grease or oil from a surface degreasing agent: A solvent or alkaline solution which is used for removing oil and grease degree: 1/360 part of a circle. degree wheel: A wheel-like unit 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. de-ice: To remove the ice from the outside of the windshield. de-icer: A liquid or spray which is applied to the windshield to assist in removing ice 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. Delaunay: An old brand of automobile of which the 1925-1948 6-cyl Belleville are classic cars. delay valve: A valve used in a vacuum or hydraulic system in which the valve's opening or closing is delayed. 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. 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 mileage only: The odometer reading reflects only the distance from the factory to the selling dealer. delivery valve: The valve on the outlet side of a pump delta configuration: A triangular connection of the three stator windings of an alternator. Also see Y-configuration 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. 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. 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 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. Also called a "detachable rim" 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: Compactness; relative mass of matter in a given volume. 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 Denver boot: A locking device which wraps around the wheel of a vehicle to immobilize its movement depolarize: Removal of residual magnetism thereby destroying or removing the magnetic. deposit: 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) 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. 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 gauge: A measuring tool for determining the depth of something. 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. derailleur chain, narrow width: chain made especially for use on an "ultra" or narrow freewheel, often recognizable by bulging inner link plates and flush chain pins. derailleur chain, standard width: 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. 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 design: [1] The arrangement of parts or the form of construction. [2] To arrange parts or construction of a vehicle or major component 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: The 1956-58 Adventurer models are milestone cars. 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 detent ball and spring: A spring loaded ball that snaps into a groove or notch to hold some sliding object in position. detergent: A 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. 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 sensor: A sensor mounted near the cylinders which can detect engine knocking 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. Devon: The 1958-62 S/S models are milestone cars. dewax: To remove a coating of wax from the body of a vehicle usually in preparation for painting. dew point: The temperature at which vapor begins to condense. DFC: Acronym for digital frequency control dhc: Acronym for drophead coupe DG: Acronym for "Diesel General" oil for use under ordinary conditions in diesel engines. diagnostic center: A garage or part of a garage where problems with a vehicle or part of a vehicle are determined. diagnostic computer: A computer terminal or engine analyzer which is hooked up to the car's electronic box and reveals the condition of the engine and various sensors. diagnostic link: The electric cord which connects the computer terminal to the socket on the vehicle. diagnostic socket: A socket on the vehicle (usually found in the engine compartment) which is part of the onboard electronic sensor system. diagnostic system: The various sensors and electronic devices which record the operation of a number of functions within the vehicle. diagnostic testing: The analysis of the various functions of the components of a vehicle to determine if they are operating properly or have recorded faults which need to be corrected. diagonal belt: Another term for shoulder belt diagonal split braking system: A dual-circuit braking system in which each circuit brakes one front wheel and the diagonally opposite rear wheel, so that in the case of failure of one circuit reasonably balanced braking can be achieved. See dual brakes -- especially the picture. diagonally split system: A dual-circuit braking system in which each circuit brakes one front wheel and the diagonally opposite rear wheel, so that in the case of failure of one circuit reasonably balanced braking can be achieved. See dual brakes -- especially the picture. dial: The face (usually circular) of an instrument like a speedometer, tachometer, vacuum gauge, etc. dial caliper: A slide-type caliper which registers on a dial the distance between two points dialed in: The action of fine tuning an engine or component to its peak capacity. dial gage: See dial gauge. dial gauge: A precision micrometer type instrument that indicates the reading via a needle moving across a dial face. dial indicator: See dial gauge. dial torque wrench: A wrench usually with a socket end and which measures the torque of a nut-bolt fastener. It registers the value on a dial. diameter: The distance between one edge of a circular object to the other edge and passing through the center diamond frame: The traditional men's bicycle frame, the principal parts of which form a diamond shape. diamonding: diamond star: The name of Chrysler Corporation which comes from the pattern of its emblem. diaphragm: A flexible cloth-rubber sheet that is stretched across an area thereby separating two different compartments. A diaphragm is used in pumps to create a pressure differential that causes a fluid to be pushed or pulled from one point to another. Some carburetors have no float bowl (i.e., Tillotsen), but use a series of diaphragms to pump gasoline into the engine. diaphram clutch: Another term for a diaphragm spring clutch diaphram link: The arm which transmits the movement of the diaphram and the distributor baseplate in a vacuum advance mechanism. diaphragm pump: A device which has a flexible diaphragm which moves forward and backward by a solenoid or other mechanical device to transfer fluid.
diaphragm spring clutch: A common clutch used in most vehicles with manual transmission where a diaphragm spring keeps the pressure plate in contact with the friction plate. dickey: British term for rumble seat. die: [1] One of a matched pair of hardened steel blocks that are used to form (by stamping, pressing, extruding, drawing or threading) metal into a desired shape. [2] A tool for cutting threads. See tap and die set. die back: die-back. die-back: In a lacquer finish, the loss of gloss after compounding, caused by continued evaporation of thinner. die cast: Manufactured by forcing molten metal into a die. Especially used of aluminum or an alloy. die casting: Formation of an object by forcing molten metal, plastic, etc., into a die. See cast. dielectric: A material which is an electrical insulator or in which an electric field can be sustained with a minimum loss of power. dielectric grease: A special grease which is applied to the ends of electric terminals to inhibit corrosion between the terminals or to be sure that there is good electrical contact between the terminals. diesel: A type of engine or fuel or oil used for that engine. See diesel engine, dieselFuel, or diesel oil diesel cycle: A four-stroke cycle where the air is sucked into the cylinder and compressed at a ratio of up to 24:1. At the end of the compression stroke the fuel is injected. Because of the high compression and resulting increase in temperature, the fuel is ignited leading to the power stroke and followed by the exhaust stroke where the combustion products are removed. diesel engine: An internal combustion engine that uses diesel oil for fuel. The true diesel does not use a carburetor or an ignition system (i.e., spark plugs) but injects diesel oil into the cylinders when the piston has compressed the air so tightly that it is hot enough to ignite the diesel fuel without a spark. Because a cold engine cannot ignite the diesel fuel, glow plugs are used to heat the mixture, but they do not provide a spark. Named after Rudolf Diesel (1858-1913), the inventor. Also see compression ignition. diesel fuel: A light oil fuel which has a relatively low ignition temperature dieseling: A form of autoignition in which a gasoline engine continues to fire after the ignition has been shut off. In late-model emission-controlled engines, dieseling or run-on is caused by heat and the unusually high manifold pressure that result from retarding the spark at idle. diesel knock: The noise caused by the rapid rise in pressure in a diesel engine especially when the engine is cold or running at a low speed. Also called "diesel rattle." dieselling: See dieseling diesel oil: Fuel for cars with diesel engines. This is not a form of lubricating oil. See cetane rating. diesel particulate filter: A filter which removes small particles from a diesel exhaust. It looks like a honeycomb catalytic converter but acts as a mechanical separator. diesel rattle: Another term for diesel knock die stock: A tool used to hold and operate dies when cutting outside threads. die size: Retread rubber is designated by its crescent shaped dimensions in inches and eighths, and its thickness in 32nds of an inch; (e.g., 66-72-16; the crown would measure 6 and 6 eighths, the base 7 and 2 eighths wide; and the thickness 16/32 of an inch, or gauge of the stock rubber.) diff: A colloquial term for a differential
differential cage: the rotating metal fram which encloses the differential side gears and pinion gears inside the axle casing. Also called the "differential carrier" differential carrier: See differential cage differential case: The steel unit to which the ring gear is attached. The case drives the spider gears and forms an inner bearing surface for the axle and gears. differential casing: The differential housing differential gear: See differential gears. differential gears: The gears that transmit engine power to the driving axles and are arranged so as to permit the rear wheels to turn at different speeds as required when the vehicle is negotiating a turn. differential grease: See gear grease. differential housing: The enclosure which contains the differential gears. differential lock: A mechanism which eliminates the action of the differential so that both wheels can be driven for better adhesion on slippery surfaces. differential pinion: The bevel pinion in the differential. differential side gear: The bevel gear on either side of the differential into the center of which the axle shaft fits diffusing lens: The lens in the headlight glass which helps to focus the beam diffusion: the way in which innovations spread through market or non-market channels. digital caliper: A slide-type caliper which gives a digital readout. digital frequency control: (DFC) A system which automatically stabilizes or tunes the frequency of a selected radio station. digital speedometer: A speedometer which shows the speed in digital numbers rather than a needle on a dial gauge (which is called an analog speedometer). dig out: To accelerate at top power. diluent: A fluid which thins or weakens another fluid. dilution: See crankcase dilution. dimmer: A switch used to lower or dip the headlights from high beam to low beam and back again. dimmer control: A rotary control switch which will increase or decrease the intensity of the instrument lights. Also called interior dimmer light switch. dimmer switch: A device used to lower or increase the brightness and focus of the headlights (i.e., from high-beam to low-beam). The British term is "dipswitch." DIN: Acronym for "Deutsche Industrie Normen" (German industrial standards). DIN horsepower is similar to the SAE net horsepower. It is measured at the output shaft of an engine fully equipped with normal accessories. dinging: The action of straightening a damaged panel by using a hammer and dolly to bring it back into shape. DIN mounting: The standard hole in the dash through which a DIN radio can be installed DIN radio: An aftermarket radio which fits into a thinner hole than most American radios. When installing a repacement radio, special faceplates are necessary diode: An electrical component having the ability to pass electric current readily in one direction but resisting current flow in the other. When four diodes are connected in a certain way (i.e., "bridged") they will convert AC to DC, thus the rectifier. Also see zener diode. dip: [1] A British term for dimming the headlights. [2] A low horizontal indentation of the pavement which may cause a speeding vehicle to lose control dipped beam: A British term for low beam dipper: A British term for the dimmer switch dipper switch: A British term for the dimmer switch dipping mirror: A British term for day-night mirror dipstick: The metal rod that passes into the oil sump it is used to determine the quantity of oil in the engine. The oil level is marked on the rod and matches level indicators on the rod. Dipsticks are used to check engine oil and transmission fluid. In most instances, the dipstick is inserted as far as it will go and then removed to check the level. In motorcycle engines, the dipstick is placed on the top of the threads (i.e., not screwed down) to check the level. dipswitch: A British term for the dimmer switch direct-acting shock absorber: A telescopic shock absorber. direct current: (DC) An electric current that flows steadily in one direction only. This is the type of current found in a battery and throughout the lighting and accessory system of a vehicle. Contrasts with alternating current (AC). direct damage: A vehicle damage caused directly by an impact with an object. In contrast with an indirect damage. direct drive: When the gearing is such that the crankshaft and driveshaft revolve at the same speed, the vehicle is in direct drive. Usually this occurs in high gear (except for those with overdrive). It is represented as 1.00:1 ratio. direct drive powertrain: A system of propulsion where the speed of the engine, transmission, and propeller shaft rotate the same. direct ignition system: An ignition system which does not used a distributor. Abbreviated DIS direct injection: A fuel injection system which is generally used in diesel engines and forces fuel directly into the combustion chamber. It requires very high injection system pressure to overcome the pressure within the combustion chamber. directional stability: Ability of a vehicle to move forward in a straight line with a minimum of driver control. A vehicle with good directional stability will not be unduly affected by side wind, road irregularities, etc. directional tire: Directional designs are recognized by the grooves in the tread that swipe away in a backward angle from the center of the tread face and rotate in only one direction. A direction of rotation arrow is located on both sidewalls of the tire. Directional tires enhance straight-line acceleration, provide maximum dry traction, and better wet performance which helps to reduce rolling resistance as well as providing shorter stopping distances. See asymmetrical tread directional tread, and directional tread: An arrangement of bars, grooves, and ribs on a tire's tread in any manner that gives most effective traction when the tire revolves in only one direction. Also see directional tire. direction indicator: The signal lights which blink on either side of the front of the vehicle and either side of the rear of the vehicle. Some early cars (like the Austin and Flying Standard) had small illuminated arms that flipped out from the B-post instead. The purpose of signal lights is to warn other drivers of a change in direction when turning a corner or changing lanes. direction indicator warning light: A light on the instrument panel which flashes when the signal lights are operating. Usually this light is in the shape of a green arrow. On some cars, like Cadillac, a secondary light is mounted in a pod on the upper edge of each front fender and in a pod inside the cab above the backlight (i.e., back window) direction of rotation: the direction in which a wheel or shaft turns or is supposed to turn. direction of travel: The direction in which an object (e.g., a vehicle) is moving. direct polarity: Direct current flowing from anode (base metal) to cathode (electrode). The electrode is negative and the base metal is positive. DIS: An acronym for direct ignition system or a distributorless ignition system disabled: [1] the condition of a vehicle which is not able to be driven because of a failure of some component (e.g., bad battery, flat tire, engine seized) or because of an accident. [2] A driver who lacks the use of a limb. disassemble: To take a vehicle or major component (e.g., the engine) apart in order to repair or restore the vehicle or component or to sell or recycle them. Also called "dismantle." disc: May be spelled "disk." A flat dish-shaped item which may or may not have a center hole. Also see brake disc type, clutch disc, and disc brake. disc brake: A type of brake that has two basic components: a flat rotor (disc) that turns with the wheel and a caliper that is stationary. When the brake pedal is depressed, linkage (mechanical or hydraulic) causes the caliper to force its heat-resistant brake pads against both sides of the rotating disc thus slowing or stopping the wheel. Almost all new cars have disc brakes on the front wheels with drum brakes on the rear. More expensive cars have four wheel disc brakes. Because of the need for greater pressure to activate disc brakes, most cars so equipped also have a power booster. Wear takes place in the pads and the rotors. The pads are usually replaced while the rotors can sometimes be reground else they too must be replaced. If the rotors are not tightened correctly when installed, they can warp and cause a jerking motion when stopping. Also see brake, disc type. disc brake gauge: A tool for measuring the thickness, wear, and score depth on brake discs disc brake rotor: See brake rotor disc brakes: See disc brake.
distributor baseplate: the fixed plate in the body of the distributor on which the contact breaker or triggering device is mounted, and through the centre of which the distributor shaft passes distributor body: the bowl-like part containing the distributor shaft with the rotor arm at its top end, and, in the conventional version, the centrifugal advance mechanism and the contact breaker distributor cam: the cam at the top of the distributor shaft with as many lobes as there are cylinders, acting on the heel of the contact breaker arm distributor cap: An insulated cover containing a central terminal or tower with a series (one per cylinder) of terminals or towers that are evenly spaced in a circular pattern around the central terminal or tower, the secondary voltage travels to the central terminal or tower where it is then channelled to one of the outer terminals or towers by the rotor. The cap also keeps dirt and moisture out of the distributor. distributor clamp: See distributor hold-down clamp distributor hold-down clamp: A metal bracket at the base of the distributor that has a nut or bolt which can be loosened to allow the distributor to be moved on its shaft to readjust ignition timing or to open the points for gapping. distributorless ignition system: (DIS or DLS) An electronic ignition system that does not have a conventional rotating distributor. Instead, it uses multi-spark ignition coils or one ignition coil for each spark plug. distributor rotor: A rotating part of the distributor which transfers high voltage to each spark plug. In a distributors with points, it is oblong-shaped; but in a distributors without points, it is usually a disc. Also called a "rotor" or "rotor arm." distributor shaft: The metal shaft inside the distributor that has a cam wheel which revolves with the shaft and forces the points to open. A spring causes the points to close. The distributor rotor is mounted on the top of this shaft. distributor tower: The terminals at the top of the distributor cap into which the spark plug wires fit. Also called "terminal tower" distributor weight: One of two flat pieces of metal found inside the distributor's centrifugal advance mechanism on the baseplate. They swing out as speed increases and consequently advances the timing of the spark. distributor wrench: A special tool used to tighten or loosen the distributor hold down clamp when installing or removing a distributor dive: The action of the front of the vehicle to point downward (or dip) during braking. The opposite is squat. Also see anti-dive system, anti-lift, anti-squat system, and brake dive. diversification: In today's market, especially in smaller centers, a dealership cannot make a profit on just one brand of vehicle -- especially foreign imports. Thus the dealership will diversify by having several brands (e.g., Mercedes-Benz, BMW, and Mazda). A car manufacturer diversifies by making several different kinds of vehicles (trucks, vans, luxury cars, family-size cars, commuter cars, compacts, convertibles, sports cars, etc.) in an attempt to reach every segment of the population. Some dealers or manufacturers may diversify by offering lawnmowers, boat motors, and motorcycles as well as automobiles (e.g., Honda) or even musical instruments (e.g., Yamaha). diversion: An alternative route which traffic has to follow due to closure of a stretch of road for repairs, etc. A detour. divert: to cause (air, a liquid, traffic, etc.) to follow a different course. For example, air is diverted to the air cleaner; traffic has been diverted around the accident site. diverter valve: A valve which adds an amount of air to the rich air-fuel mixture entering the intake manifold during deceleration. See air gulp valve divided propeller shaft: A propeller shaft, usually in long chassis rear-wheel drive vehicles, which is divided into two sections with a bearing and CV joint mounted on a chassis crossmember at the central point. Also called "divided propshaft" divided propshaft: A propeller shaft, usually in long chassis rear-wheel drive vehicles, which is divided into two sections with a bearing and CV joint mounted on a chassis crossmember at the central point. Also called "divided propeller shaft" divider: A measuring tool with two straight pointed arms used to mark off and transfer measurements, e.g., on sheet metal or other metal components DIY: An acronym for "Do-it-yourself." Also see do-it-yourself market. DIY mechanic: A person, whether qualified or not, who does his own repairs on his own vehicle. DL: An abbreviation for deluxe which is usually applied to a series of vehicles which is one step up from "custom" DLI: Acronym for "distributorless ignition" dlr: Abbreviation for "dealer" dnf: A racing term for "Did not finish" Doble: The 1925-1948 models are classic cars. DOC: Acronym for "double overhead camshafts" Dodge: The 1967-70 Coronet R/T models are milestone cars. The 1968-70 Charger R/T and Daytona models are milestone cars. dog: [1] Man's best friend. [2] A vehicle in very bad shape, which may not be man's best friend. [3] A lug or protrusion on an object. 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. 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
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. dolly: [1] 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. [2] A small two-wheeled trolley for moving heavy objects. [3] A trolley that supports the front wheels or back wheels of a disabled vehicle for towing it. 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." 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 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." 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 moulding 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: [1] the bare skeleton of the door to which the door skin and door trim are added. [2] the door aperture. door gap: the distance around the door between the edge of the door and the aperture 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 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 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 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 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. Dorris: 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. DOT: Acronym for "Department of Transportation" -- an American federal agency or "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 401° minimum and wet boiling point of 284° 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 446° minimum and wet boiling point of 311° 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 500° 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 500° minimum and wet boiling point of 356° 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 4 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-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-barrel carburetor: Two throttle openings or barrels from the carburetor to the intake manifold. Also see four-barrel carburetor, and single-barrel carburetor. Also called "twin-choke carburetor." 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 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-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-ended spanner: British term for double-ended wrench double-ended wrench: a tool which has a hexagon ring at each end. 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. 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 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 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 and single-pivot steering double reduction gearing: gearing in which the ratio is reduced in two stages, used especially in heavy trucks double roller chain: See duplex chain 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 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." 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. dowel pin: A pin (steel or wood), passed through or partly through, two parts to provide proper alignment and to prevent movement between them. Sometimes called "locating pin." 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 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." downshifting: Manually shifting to a lower gear in order to use the engine compression to assist in reducing the vehicle's speed. Also called "downgearing." downstroke: The downward movement of the piston, either the intake stroke or the power stroke in a four-cycle engine. 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 tube running from the headset to the bottom bracket, one part of the main triangle on a bicycle frame. downward change: A British expression of shifting the transmission to a lower gear. The North American term is downshift. D-pillar: The fourth vertical post in a van or station wagon. Also called D-post D-post: The fourth vertical pillar in a van or station wagon. Also called D-pillar dr: Abbreviation for "door," as in 2-dr. Sedan." draft: An unpleasant current of air intruding into the interior of a car drafting: The action of following closely behind a faster vehicle so as to take advantage of the aerodynamic effect which causes both the vehicles behind and the one in front to move faster. See slip stream. drag: [1] To accelerate a vehicle from a standing start, over a course one-fourth mile in length. Also called "drag racing." [2] Used by some drivers when referring to challenging another driver to an acceleration race. [3] Air resistance. See aerodynamic drag. [4] The condition of a clutch when it fails to fully disengage. The plates still rub against each other and causes intermittent contact between the engine output and the transmission gears. Called "clutch drag." [5] The condition of brakes when the pads or shoes still rub the disc or drum. Called "brake drag." drag coefficient: (Cd) A number used in calculating the aerodynamic drag acting on a vehicle. The drag coefficient is a function of factors like the shape of the vehicle, airflow through the vehicle for ventilation and cooling. The number is determined in a wind-tunnel or by coasting tests performed on the vehicle. The lower the drag coefficient the less drag on the vehicle and the more aerodynamic is the vehicle. A sleek vehicle has a drag coefficient, or "Cd," of about 0.30; a square, flat plate's is 1.98. Also signified by Cx. drag link: A steel rod connecting the pitman arm to one of the steering knuckles. On some installations the drag link connects the pitman arm to a center idler arm. drag race: A competitive match between two vehicles in which they race over a 1/4 mile course. dragster: A specially constructed car for drag racing, typically with a huge supercharged V-8 engine mounted well back in the chassis and extremely wide rear tires dragstrip: A quarter-mile stretch of track for drag racing drag wheel: Special steering wheel used on some dragsters. Often consists of a crossbar spoke and a portion of rim on each end. drain: [1] To empty a container usually from the bottom. [2] A tube or channel which allows water to run to another place. draincock: A petcock or drain tap drain hole: A hole drilled in the bottom of a box section or a door, to allow water that has accumulated to escape so as to prevent or delay rusting draining tray: A container used to catch oil when draining the sump, transmission, etc. drain plug: Usually a threaded plug at the lowest point of the sump, gearbox, cooling system, etc., which is removed in order to drain the oil or coolant, and typically has a recessed hexagon head. See oil drain plug. drain plug key: A tool for removing and tightening drain plugs, e.g., on transmissions and engine sumps, either as a multi-purpose tool with a number of different drives in the form of hexagonal or square projections at either end for different drain plugs, or as a special tool for one specific size of drain plug. Also called a "drain plug wrench." drain plug spanner: A British term for a drain plug wrench drain tap: A device which controls the flow of fluid (oil or coolant) out of the bottom of the cylinder block or the bottom of the radiator. drain plug wrench: A tool for removing and tightening drain plugs, e.g., on transmissions and engine sumps, either as a multi-purpose tool with a number of different drives in the form of hexagonal or square projections at either end for different drain plugs, or as a special tool for one specific size of drain plug. Also called a "drain plug key." draught: British spelling for "draft" draught excluder: A British term for "weatherstrip" draw: [1] To form wires by pulling the wire stock through a series of hardened dies. [2] The process of removing the hardness from a piece of metal. [3] The amount of electrical load or electrical requirement. drawbar: two converging bars forming a V-frame or an A-frame at the front of a trailer or motorhome, which carry the coupling for attaching to the towing vehicle draw filing: draw-filing. draw-filing: Filing by passing the file, at right angles, up and down the length of the work. dream car: A one-of-a-kind futuristic, experimental automobile usually appearing at auto shows to stimulate interest in the manufacturer's products. Much design benefit spurs from dream cars and many reach the production stage. dress: [1] to give (a rough surface, flanges, etc.) the right shape by grinding or a similar process. [2] To prepare ore for smelting by removing impurities. drier: [1] A dehumidifier. [2] A drying oven drift: [1] A short bar or punch used with a hammer to drive a component in or out of place for removal or installation. [2] To deviate from the normal direction. See four-wheel Drift and tire deviation angle. drift punch: A tapered tool which is hit with a hammer and used to remove or install pins, shafts, rivets, etc. or to align holes when inserting screws and bolts. drill: [1] A tool used to bore holes. [2] The action of using a drill to make a hole. Also see letter drills, number drills, and twist drill. drill bit: A piece of rod with spiral recesses cut in it and a hardened steel tip, made in different sizes for drilling different sized holes, and inserted in the chuck of a drill drilled: An expression used to describe a hole which has been cut into a crankshaft to allow oil to be fed to the main bearings on the connecting rod throws. drill press: A nonportable machine used for drilling. d ring: See D-ring. d-ring: A D-shaped ring found on many models of bicycle shift levers, used to adjust the level of tension on the inner parts of the lever. drip moulding: British term for "drip rail" drip rail: A gutter running along either side of the roof to take water to the front or rear of the car, and prevent it from dripping into the car when the door is opened. The British term is "drip moulding" drivable: The condition of a vehicle which may have many mechanical and appearance problems, but it has an engine which runs and wheels that turn, etc. so that it can be operated and driven. drivability: The general qualitative evaluation of a powertrain's operating qualities, including idle smoothness, cold and hot starting, throttle response, power delivery, and tolerance for altitude changes. drive: [1] to travel in a car as in the expression, "We drove to Chicago." [2] to operate a vehicle as in the expression, "Martha drove to New York by herself." [3] to cause a wheel, shaft, etc. to turn or rotate. [4] to propel a vehicle. [5] a journey in a car as in "The drive to Chicago was uneventful." [6] to go for a drive as in, "We went for a drive last Sunday." [7] A stretch of private road leading to a house (i.e., driveway). [8] A means of transmitting power or motion as in "The drive is controlled by a servo switch." [9] A tool which has a square end (1/4 inch, 3/8 inch, or 1/2 inch) which fits into a recess in a corresponding socket for the installation or removal of nuts and bolts. [10] a die position. [11] One of the forward gears marked on the gear selector of an automatic transmission. drive belt: A flat belt which connects two or more pulleys so as to transmit motion from one pulley to the other drive chain: An endless chain which encircles two or more sprockets so as to transmit motion from one sprocket to the other drive end: The end of an alternator, generator, etc., where the drive pulley or gear is located. drive end bracket: The cover which houses the drive end of an alternator or generator drive fit: A condition of fit (contact) between two parts that requires pressure to force the parts together. Usually the shaft is slightly larger than the hole so that they must be pounded or forced or driven together. Also called "force fit," "press fit," or "interference fit." drive gear: The gear which transmits the power to a driven gear drive handle: A tool, typically in the form of a bar, for turning sockets to loosen and tighten nuts and bolts, with a male square drive to be inserted into the female square drive of sockets for the turning operation. They include ratchets, jointed handles, speed brace, T-handles, torque wrenches, speeeder handle, and breaker bar drive layout: The arrangement of the order of the engine, transmission, and driven axles, e.g., Front-wheel drive, rear-wheel drive, mid-engine drive, four-wheel drive, two-wheel drive driveline: All the individual components beyond the engine up to the wheels (e.g., clutch, drive shaft, differential, driven axles); but not the engine or transmission. Also called "drivetrain" or "powertrain" drive module: interchangeable unit providing motive power, either in the form of an electric motor and ancillaries, or an internal combustion engine with all necessary components, for alternative use in the same vehicle according to needs and conditions drive motor: electric motor providing motive power in an electric vehicle driven: Something made to rotate by the engine or some other source of motive power driven axle: The axle to which power is transmitted to drive the vehicle driven gear: An engine needs to transmit power to the wheels by the use of sprockets and chain (as in a motorcycle) or by a drive gear which meshes with a driven gear to propel the vehicle. driven plate: The central clutch plate carrying clutch linings and held under pressure between the flywheel and the pressure plate when the clutch pedal is released, and transmitting power to the gearbox input shaft via splines driven pulley: A pulley which is surrounded by a belt to receive power from the drive pulley driven sprocket: On a vehicle which uses a chain (like a bicycle and some motorcycles), there are two important sprockets: the drive sprocket is connected to the power source (the engine or your pedals) and the driven sprocket is usually connected to your rear wheel. driven wheel: The wheel (or wheels) to which power is transmitted to drive the vehicle
drive plate: A light plate bolted to the crankshaft to which the torque converter is attached in a vehicle with automatic transmission drive pulley: A pulley which is surrounded by a belt to transmit power to the driven pulley driver: [1] A collectible vehicle which is too good to treat as a beater and not quite good enough to show. It is a presentable old car or truck that is used for everyday purposes. It is maintained as though it were a late-model vehicle. With care, it could be easily restored to show car condition. [2] A person who operates the controls of a vehicle to regulate its speed and direction. [3] A tool used to insert something like a fastening device (e.g., screwdriver). [4] Also see drivers. driver air bag: original type of air bag, designed to protect the driver from being hurled into the steering wheel and instrument panel Driver and Vehicle Licensing Agency (DVLA): A section of the British Department of Transport which is responsible for keeping records of all registered vehicles and issuing registrations and licences for vehicles as well as licences for drivers. The center is located in Swansea. Driver and Vehicle Licensing Center: The location for the British Driver and Vehicle Licensing Agency located in Swansea. driver error: A mistake made by the operator of a vehicle particularly when there is an accident. An accident may be caused by a vehicle failure (e.g., a tire blowout), unsafe road conditions (e.g., snow, ice, fallen rock or tree), the inattention of a pedestrian, or the fault of a driver (e.g., drunkenness, inattention, intentional damage, disobedience to rules of the road). driver evaluation: A test of a driver's ability to handle a vehicle. May be used to grant a driver's licence for a particular type of vehicle (i.e., motorcycle, passenger car, truck, bus, taxi) drivers: Colloquial term for "drive axle tires." Also see rim drivers.
drive shaft: See driveshaft. driveshaft safety strap: A metal strap or straps, surrounding the driveshaft to prevent the shaft from falling to the ground in the event of a universal joint or shaft failure. drive sprocket: On a vehicle which uses a chain (like a bicycle and some motorcycles), there are two important sprockets: the drive sprocket is connected to the power source (the engine or your pedals) and the driven sprocket is usually connected to your rear wheel. drive tool: Any accessory for use with a socket wrench, including the drive handle drive train: [1] This term refers to the entire moving part of the car: Engine, clutch, transmission, driveshaft, differential, axles, and sometimes the wheels. [2] The derailleurs, chain, freewheel, and crankset of a bicycle. drivetrain: [1] This term refers to the entire moving part of the car: Engine, clutch, transmission, driveshaft, differential, axles, and sometimes the wheels. [2] The derailleurs, chain, freewheel, and crankset of a bicycle. driveway: A short drive, often leading to a garage driving: [1] providing motive power, making a gear, shaft, etc. rotate. [2] Controlling the movement and direction of a vehicle. driving axle: The axle which is driven by the engine through the drivetrain. Also called the "drive axle" or "driven axle" driving conditions: The situation created by the amount of traffic, the weather, and state of the roads driving gear: The gear which is driven by the engine. Also called the "driven gear" driving habits: The personal behaviour of the driver when controlling the vehicle, including the speeds he travels, how and when he shifts gears, how he uses the brakes, when and if he uses his signal lights, how he changes lanes, how he turns corners, etc. driving lamp: A British term for "driving light" or "spot light" driving licence: A British term for "driver's licence" or "operator's licence." A document which allows the holder to drive a certain type or types of vehicle, and is the only document required to be carried by the driver in Britain driving light: An auxiliary light used at night to illuminate the side of the road and increase the viewing distance. driving mirror: A British term for either the interior rear-view mirror or the mirrors mounted on the outside of the front doors or the front fenders driving position: The position in which the driver grasps the steering wheel and adjusts the location of the seat in relation to the pedals. driving style: The manner in which the driver handles a vehicle. See sporty driving style driving wheel: The wheel(s) which is driven by the engine through the drivetrain. Also called the "driven wheel" drop: [1] A sudden reduction of pressure or voltage, etc. [2] The vertical distance from the horizontal line connecting the two wheel axles and the bottom bracket, one way of determining the location of the bottom bracket in relation to the rest of the bicycle frame. Also see drops. drop arm: A British term for the pitman arm drop-centre axle: A beam axle in which the main central portion of the beam is lower than the wheel centers, which was the usual layout for front axles until independent front suspension became almost universal drop-center rim: See drop center rim drop center rim: A one-piece rim with a deep center section which is lower than the two outer edges, this allows the bead of the tire to be pushed into the low area on one side while the other side is pulled over and off the flange. The British term is "well-base rim" drop center rim taper: A passenger rim where both bead seats are tapered 5° or a tubeless truck rim where both bead seats are tapered 15°. drop-centre rim: See drop center rim drop centre rim: See drop center rim drop forged: A part that has been formed by heating the steel blank red hot and pounding it into shape with a powerful drop hammer. drophead: [1] A convertible. [2] having a folding top which can be raised or lowered over the passenger compartment. See drophead coupé. drophead coupe: This is a two-door automobile which has the appearance of a convertible, but the roof is fixed in place. Abbreviated: dhc. In Europe, it is called a "cabriolet." drophead coupé: This is a two-door automobile which has the appearance of a convertible, but the roof is fixed in place. Abbreviated: dhc. In Europe, it is called a "cabriolet." dropout: A slot in the frame into which the rear wheel axle fits. Also see fork tips. dropout hanger: A threaded metal piece that extends below the right rear dropout of a bicycle, used as a mount for the rear derailleur. dropped axle: A front axle that has been altered so as to lower the frame of the vehicle, consists of bending the axle downward at the outer ends. drops: The lower, straight portion of a turned-down-type handlebar set. droptop: A colloquial term for "convertible." drum: [1] A cylindrical container. [2] A housing for transmission gears where the bands are located. [3] To make a "whump, whump" sound. Also see brake drum, brake drum lathe, and drum brake. drum brake: A type of brake using a shallow drum-shaped metal cylinder that attaches to the inner surface of the wheel and rotates with it. When you press down on the brake pedal, curved brake shoes with friction linings press against the inner circumference of the drum to slow or stop the vehicle. Also see brake drum. drum brakes: See drum brake. dry: [1] For paint, to lose its wetness often to the place where the surface is not even tacky. [2] For bearings, to lack grease or other lubricant. dry ballast: A form of ballasting where a fine powder of barium sulphate is inserted inside the tire. It is sometimes referred to incorrectly as "Lead" ballast because of one brand name, "Ledballast." dry battery: See dry cell. dry boiling point: The temperature at which fresh brake fluid from a new container will boil. See wet boiling point and DOT 3. dry cell: A battery (like a flashlight battery) that uses no liquid electrolyte. dry charged battery: A battery with the plates charged but lacking electrolyte, when ready to be placed in service, the electrolyte is added. dry clutch: A clutch with only one plate. dry friction: dry friction exists when the rubbing parts have no other substance between them and are clean of other materials (i.e., no grease or oil). Opposite to wet friction. dry galvanizing: A hot-dip galvanizing method in which the metal components are first immersed in a solution of flux and then dried, so that they become pre-coated with a thin film of flux, which melts in the zinc bath, to which certain metals, such as tin and aluminum, may be added to give fluidity, and in the case of tin, brightness. The opposite is wet galvanizing drying oven: An enclosure where painted vehicle bodies are subjected to heat in order to dry and/or bake on the paint dry joint: A faulty electrical joint which does not give proper contact dry liner: When a cylinder sleeve is pressed into a bore and the cooling fluid does not contact the outside of the sleeve, the engine has a dry liner. Also see liner. dry sleeve: A cylinder sleeve application in which the sleeve is supported in the block metal over its entire length, the coolant does not touch the sleeve itself. Also see wet sleeve. dry spray: dry-spray. dry-spray: atomized paint that does not dissolve into the material being sprayed. It is caused by holding the gun too far from the work, too much air pressure or a solvent that evaporates too fast. dry sump: A lubrication system in which the engine's supply of oil is not contained in the crankcase (sump) but is pumped to the engine from an external container. This system allows the crankcase to be reduced in size and the engine to be installed lower in the chassis, and eliminates the oil starvation most conventional oiling systems suffer when subjected to the accelerative, braking, and cornering forces generated by a racing car. dry sump lubrication: See dry sump dry weight: The weight of a vehicle without any fuel, oil, or coolant. Also see curb weight and gross vehicle weight DS: Acronym for "Diesel Severe" oil for use in under adverse conditions in diesel engines. dual: [1] a combination of two nearly identical parts (e.g., a truck with dual tires has two tires at each end of the axle). [2] In Britain, dual is a verb meaning to twin a highway or railroad. dual-acting: See double-acting dual axles: See tandem axles. dual bead tire: Heavy service and large truck tires using two or more sets of bead wires in each bead rather than one. dual-bed catalytic converter: A catalytic converter which combines two converters (with different catalysts) in a single housing dual brake: See dual brakes.
dual braking system: See dual brakes. dual breaker points: A distributor using two sets of breaker points to increase the cam angle so that at high engine speeds, sufficient spark will be produced to fire the plugs. dual carbs: Two carburetors on the same engine. dual carburetors: Two carburetors on the same engine. dual carriageway: A British term for a divided highway (i.e., a road that has four lanes -- two in one direction and two in the other -- separated by a median). dual-circuit braking system: See dual brakes dual controls: A second set of controls for use by a driving instructor when teaching someone to drive dual drive: [1] Tandem axles, both powered directly by the engine. [2] Colloquial term for twin screw. dual exhaust system: See twin exhausts Dual Ghia: The 1956-58 models are milestone cars. dual ignition system: See twin ignition system dual-line braking system: A braking system in which a towing vehicle and trailer are connected by two or more brake lines dual mounting: Two tires mounted together on each side of an axle of several types: cast spoke type, disc wheel type (held on by double cap nuts or inner cap nuts and outer cap nuts), Chevrolet type, motor wheel type dual overhead cam engine: See double overhead cam engine. dual-piston engine: See twin-piston engine dual-piston master cylinder: See tandem master cylinder dual-range gearbox: See dual-range transmission dual-range transmission: A transmission in a four-wheel drive vehicle and some motorcycles with two sets of ratios, usually a higher set for road use and a lower set for off-road use. duals: [1] Two sets of exhaust pipes and mufflers -- one for each bank of cylinders. [2] Two tires on each end of an axle. dual spacing: A measurement in inches (or millimeters) from the center of the tread of one tire, to the center tread of the other tire in dual, which provides clearance between duals for air circulation. dual-tone horn: See two-tone horn Dubonnet suspension: An independent front suspension and steering arrangement used in the 1930s and '40s, in which the axle beam is rigidly attached to the vehicle frame, and the kingpins carry sprung steering and suspension arms, from which the wheels are mounted on stub axles duct: A tube through which air, gas, or liquid is conducted. See NACA duct. ductile: metal which can be bent, hammered, or drawn out into wire or sheet without fracturing ductility: The ability of a material to undergo stretching or bending without fracturing Duesenberg: The 1925-1948 models are classic cars. duesy: Expression to indicate quality, as "It's a duesy." The word is derived from the high quality Duesenberg automobiles. dull: [1] A finish that is not shiny. [2] A blade, saw, or drill bit that is not sharp. dumbirons: The front extensions of the side members of a chassis frarne in older designs, to which were fitted the front ends of the leaf springs carrying the front axle. dummy: A stuffed figure made to look like a human being, used, for instance, when crash testing cars. Also called a crash test dummy. dummy lights: Exterior lights which do not work, but may enhance the appearance of a vehicle. dump body: A large truck's metal body which is generally hinged at rear and dumped by hydraulic means. The size is generally given in cubic yard water level capacity. dump truck: [1] A large truck with a bed designed to be tilted at its front to unload its contents usually through a gate in the rear. [2] In Britain it is a small truck with a tipping container in front of the driver, used in construction, like a front-end loader dump valve: A valve for relieving pressure, such as that between the turbocharger and the carburetor in some systems duo-servo brake: A servo brake with one double-end wheel cylinder and two linked self-energizing brake shoes duplex chain: A chain with two rows of rollers. used especially for timing chains. Also see simplex chain and triplex chain DuPont: The 1925-1948 models are classic cars. durability: The ability of a component or entire vehicle to last a long time durable: The ability of something to be serviceable for a long time before being replaced duration: The length of time that an action is allowed to operate. See valve duration. durometer: A device to indicate the hardness of rubber. dust boot: A covering (often shaped like an accordian) usually made of rubber or plastic to cover over a shaft, CV joint, etc. dust cap: [1] A metal or plastic covering that fits into a hub shell to keep contaminants out of hub bearings. [2] A metal or plastic end cover for a spindle in a pedal or a cotterless crankset. dust cover: A soft, flexible valve cap to protect the valve assembly from dust while in shipment and storage. It is not capable of sealing the air pressure and should not be used in service. dust-free paint: A condition of paint which has hardened beyond being tacky so that any air-borne dust particles will not be imbedded in the paint. dust sheet: A sheet for covering a car when in a garage and not in use. Also see car cover dust shield: Sheet metal disc or plate placed on the brake assembly to keep debris from brake assembly. Also called "splash shield." duty drawback: import duties or taxes repaid by a government in whole or in part, when the imported goods are re-exported or used in the manufacture of exported goods. duty paid value: in respect to imported goods, is the aggregate value for duty on imported goods. duty waiver: forgiveness, in whole or in part, of import duties when certain conditions are met. DVLA: Acronym for Driver and Vehicle Licensing Agency DVLC: Acronym for Driver and Vehicle Licensing Center dwell: [1] In a contact breaker ignition system, the number of degrees the breaker cam rotates from the time the breaker points close until they open again. Also called the "dwell angle" or "dwell period." [2] In a breakerless ignition system, the time during which the electronic control unit allows current to flow through the primary winding of the coil, which in ignition systems with a Hall generator is determined by the width of the vanes dwell angle: See dwell. dwell-angle control: A system which makes sure that the dwell is sufficient for all engine conditions dwell-angle map: The pattern described by the electronic dwell-angle control, dependent on engine speed and battery voltage dwell meter: An instrument which determines the number of degrees the breaker cam rotates while the breaker points are closed. Changing the point gap affects the dwell angle. When the breaker points are correctly gapped, the distributor can give the proper amount and duration of spark to the spark plugs. dwell period: The time during which the primary circuit is closed and primary current flows through the ignition coil, given in crankshaft or distributor shaft degrees and therefore also called dwell angle. See dwell. DWS: Acronym for deflation warning system
dynamic balance: When the center line of the weight mass of a revolving object is in the same plane as the center line of the object, that object would be in dynamic balance. For example, the weight mass of the tire must be in the same plane as the center line of the wheel. Static balance is made off the vehicle and determined with the tire stationary. Dynamic balance is made with the tire in rotation. dynamic ignition timing: Before the introduction of a strobe light, ignition timing was done statically in that the distributor was moved a certain measured amount. With modern engines, a timing light or strobe light is used. It is connected, generally, with the spark plug of the number one cylinder. As power is provided to that cylinder from the coil, the timing light flashes. When the light is projected to the flywheel, the timing marks are illuminated. Moving the distributor will make the timing mark move closer to a fixed mark (retarded) or further away (advanced). Also called stroboscopic ignition timing. The opposite is static ignition timing dynamic imbalance: lack of balance in a rotating part such as a wheel, which can cause vibration and shudder dynamic seal: oil seal between a moving and a stationary part. Opposite to static seal dynamic supercharging: The pressurizing of the air/fuel mixture using the natural dynamic behaviour of the aspirated air, and not some mechanical device to compress it dynamo: A British term for a generator producing direct current. Also see alternator. dynamometer: An electric or hydraulic machine used to measure the actual engine horsepower output and torque. An engine dynamometer measures horsepower at the crankshaft and a chassis dynamometer measures horsepower output at the wheels. dynastart: A combined generator and starter used on some cars in the 1920s and '30s, and more recently on two-stroke motorcycles dynastarter: A combined generator and starter used on some cars in the 1920s and '30s, and more recently on two-stroke motorcycles |
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