Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "In"

Inbedability: The ability of a precision insert bearing to allow a small abrasive particle to imbed itself in the bearing material so it will not scratch the surface of the journal.

Inboard: Located near the vehicle center rather than at the outside. Opposite of Outboard

Inboard brake: See
Inboard brakes.

Inboard brakes: Most cars have the brakes associated with the wheel. Drum brakes, for instance, are located in the wheel Hub itself. Disc brakes are found attached to the wheel. However, inboard brakes are not located within the wheel. Instead, they are found attached to the Differential housing or axle shaft. Thus they are generally located only on the rear of the vehicle. Some racing cars (i.e., Formula 1) have them on the front as well. Inboard brakes mean a reduction in Unsprung weight and usually better cooling.

Inboard motor: An engine which is located within a boat rather than being attached to the back (outboard motor).

Inboard starter: A Bendix starter

Incandescent lamp: A glass enclosure in which light is produced when a tungsten filament is electrically heated so that it glows. Much of the energy is converted into heat; therefore, this class of lamp is a relatively inefficient source of light. Included in this category are the familiar screw-in light bulbs, as well as somewhat more efficient lamps, such as tungsten halogen lamps, reflector or r-lamps, parabolic aluminized reflector (PAR) lamps, and ellipsoidal reflector (ER) lamps.

Incandescent bulb: light bulbs, including regular or energy-efficient light bulbs: An incandescent bulb is a type of electric light in which light is produced by a filament heated by electric current. The most common example is the type you find in most table and floor lamps. In commercial buildings, incandescent lights are used for display lights in retail stores, hotels and motels. This includes the very small, high-intensity track lights used to display merchandise or provide spot illumination in restaurants. Energy efficient light bulbs, known as watt-savers, use less energy than a standard incandescent bulb. Long-life bulbs, bulbs that last longer than standard incandescent but produce considerably less light, are not considered energy-efficient bulbs. This category also includes halogen lamps. Halogen lamps are a special type of incandescent lamp containing halogen gas to produce a brighter, whiter light than standard incandescent. Halogen lamps come in three styles: bulbs, models with reflectors, and infrared models with reflectors. Halogen lamps are especially suited to recessed or canned fixtures, track lights, and outdoor lights.

In-car entertainment: (ICE) A car audio system, typically consisting of a radio/cassette player and perhaps a CD player. The term also includes a CB radio, TV, VCR, DVD available on some models (e.g., limousines and sleepers on large trucks)

In-car sensor: A dual bimetal strip that samples passenger compartment air and controls a vacuum modulator. The vacuum modulator controls the heating or air conditioner blend door to maintain a constant temperature in the passenger compartment

Inches of mercury: (in-Hg) a unit of measurement which designates the relative amount of vacuum present in a closed system

Incipient crack: A crack which has just started to form

Incl: Abbreviation for includes, as in price incl. tax.

Inclination: A set angle.

Also See
Kingpin inclination
Steering axis inclination

Incline

A slope
To slope

Inclined engine: An in-line engine in which the cylinders are inclined to the vertical. Also called a sloper or slant six (e.g., Chrysler's 6-cylinder engine

Inclined plane: A Wedge used to raise a load more easily. The load moves, not the wedge.

Inclinometer: See
Clinometer

Included angle: The sum of the Camber and Kingpin inclination (or steering axis inclination) angles. This angle is designed into the steering knuckle and must remain constant.

Included Angle of Thread: The angle between the flanks or the thread measured in an axial plane.

Inclusions: See
Slag inclusions

Incomplete thread

A thread with incomplete thread profile
On straight threads, that portion at the end having roots not fully formed by the lead or chamfer on threading tools

Increased shank: A shank diameter greater than thread diameter

Increasing adapter: An adapter whose male end for the socket is bigger than the female end for the drive handle. The opposite is a Reducing adapter

Increasing-radius corner: A turn where the arc becomes less sharp as you go through the curve

In-dash gauge: A gauge mounted in the instrument panel

Indentation: A concentrated panel damage or specific dent that may be caused when a car hits a relatively small obstacle, i.e., the hitch ball of another car

Indentation hardness: The resistance of a metal (or plastic) surface to indentation when subjected to pressure by a hard pointed or rounded tool

Independent ABS: An ABS in which the ABS hydraulic components are connected to, but separate from, the normal brake hydraulic system and power booster. Sometimes called a Non-integral system or Non-integrated system

Independent front suspension: (IFS) A Suspension system where the two front wheels are sprung independently from each other. It has the advantage over a Beam axle suspension because it allows the engine to be positioned further forward and lower between the wheels. In this way there is more room for the passengers, the position of the Hood is lower, the vehicle has a lower Center of gravity, and the Unsprung weight is reduced. When the front wheels are not independently sprung, there is some Caster wobble and Shimmy that make it difficult to hold on to the Steering wheel.

Also See
Independent suspension

Independent lessor: Independent lessors are usually individual businesses that can provide for the lease of virtually any make or model of vehicle. Independent lessors, like dealers, can write custom leases, including those with different conditions and special mileage considerations.

Independent rear suspension: (IRS) A Suspension system where the two rear wheels are sprung independently from each other. It has the advantage over a Beam axle suspension because the Unsprung weight is reduced, the ride and handling over rough roads are improved, and a larger Trunk with a lower floor can be placed between the wheels.

Also See
Independent suspension
Multi-link independent rear suspension

Independent repair shop: A small service outlet offering specialized repair services. They usually do not sell gasoline.

Independent suspension: A Suspension system that allows each wheel to move up and down without undue influence on the other wheels. Thus independent suspension on the rear wheels means that if only the right rear wheel hits a bump, the left rear wheel is not affected by it. Generally it is more expensive to manufacture independent suspension.

Independent Trucker: See
Owner Operator

Index: See
Anti-knock index
Cetane Index
Choke Index
Diesel Index
Energy Utilization Index
Heat Index
Load index
Temperature-humidity Index
Viscosity index

Index improver: See
Viscosity index improver

Index shifter: See
Index shifters.

Index shifters: Bicycle levers that click into distinct positions that correspond to certain Freewheel Cogs and don't require fine-tuning after each shift.

Indian: Click image for books on
Indian

A motorcycle manufacturer

Indicated horsepower: (IHP) A measure of the power developed by the burning fuel within the Cylinders. The theoretical power of an engine calculated from the MEP in the cylinders rather than at the shaft. IHP includes Bhp plus the power lost to friction, and pumping needed for the induction of the fuel and air charge into the engine and the expulsion of combustion gases

Indicated mean effective pressure: (IMEP) The average pressure within an engine cylinder during a working cycle, calculated from an indicator diagram

Indicated pressure: See
Mean indicated pressure

Indicator

An instrument which reveals the condition of a particular component.
A British term for a signal light.
An instrument for recording engine cylinder pressure.

Also See
Attitude Indicator
Battery charge indicator
Battery discharge indicator
Beam indicator
Brake Fluid Level Indicator
Brake pad wear indicator
Cable-angle Indicator
Catalyst indicator
Dial gauge
Dial indicator
Direction indicator warning light
Direction indicator
Draft Indicator
Fluid level warning indicator
Fuel consumption indicator
Gear indicator
Gear selector indicator
Glow plug indicator
Headlight retractor indicator lamp
High beam indicator
Liquid Indicator
Low fuel indicator
Low pressure indicator
Main beam indicator
Moisture Indicator
Pad Wear Indicator
Self-cancelling indicator
Semaphore indicator
Slow down indicator
Tread-wear indicators
Turn signal indicator
Wear Indicator

Indicator diagram: A cylinder pressure chart, plotted against the working cycle of a piston or engine

Indicator lamp: See
Headlight retractor indicator lamp

Indicator light: A light on the instrument panel that lights up to show the operation of something, such as the illuminated arrow that indicates the direction in which a vehicle is about to turn, the high beam indicator, battery charge indicator, oil pressure light, cruise control light, etc.
Also see
Malfunction Indicator Light
Shift Indicator Light

Indicator Reading: See
Total Indicator Reading

Indicator warning light: See
Direction indicator warning light

Indirect Damage: A type of damage not caused by immediate impact but by the spread of the impact force into other areas of the body, e.g., bulging or dents at the rear of the front fender and the leading edge of the door in the case of direct accident damage to the front edge of the front fender. The opposite is Direct damage

Indirect ignition system: A system in which the ignition means functions to ignite the main burner gas and the igniter sensing device proves the ability of the ignition means to ignite the main burner gas.

Indirect injection

(IDI)

A type of fuel injection in which the air-fuel mixture does not go into the main combustion chamber but into some kind of prechamber; injection pressures are lower than with Direct injection and Ignition lag is short
In diesel engines with in-direct injection the fuel is injected to an auxiliary pre-chamber. Combustion starts in the prechamber and propagates to the cylinder.

Indirect injection engine: A British term for a pre-combustion engine, i.e., a diesel engine using Indirect injection

Indirect internal reforming: The reformer section is separated, but adjacent to, the fuel cell anode. This structure takes advantage of the close coupled thermal benefit from the exothermic reaction of the fuel cell to support the endothermic reforming reaction.

Indium: A metallic element with the symbol In and atomic number of 49. It is used in the manufacture of transistors and as a bonding material for acoustic Transducers.

Individual valve Main Burner: A valve that controls the fuel supply to an individual main burner.

Induce: To cause or to bring about

Induce a voltage: To produce a voltage by electromagnetic induction

Induced-Draft burner: A burner which depends on the draft induced by a fan beyond the gas utilization equipment for its proper operation.

Induced magnetism: Ability of a magnetic field to produce magnetism in a metal.

Inducer: In a turbocharger, the section of the compressor wheel that draws air or air/fuel mixture into the compressor

Inductance: (L) The characteristic of a coil or wire to cause the current to lag the voltage in time phase. Inductance is measured in henrys (H)
See
Mutual inductance

Induction

The imparting of electricity into one object, not connected, to another by the influence of Magnetic fields. Found in automobiles in coils and Solenoids.
A means of transferring electrical energy in the form of a magnetic field. Principle used in the ignition coil to increase voltage
The intake of air and fuel through the carburetor, inlet manifold, and inlet ports into the combustion chamber.

Also See
Cold air induction
Electromagnetic Induction
Ram induction
Reed valve induction timing
Self-induction
Third port induction

Induction coil: See
Coil.

Induction hardening: Method of heating cast iron (e.g., valve seats) to approx 927°C which hardens it to a depth of 0.05 to 0.08 inches

Induction manifold: See
Inlet manifold

Induction motor: An ac motor which operates on principle of rotating magnetic field. Rotor has no electrical connection, but receives electrical energy by transformer action from field windings.
Also see
Repulsion-start Induction Motor

Induction noise: The sound caused by the intake of air by an engine at full throttle

Induction period: The time during the charge changing process of the engine that allows for the intake of the fresh charge into the cylinder while the inlet control, i.e., the valve or port, remains open

Induction pipe: The duct, typically an alloy manifold, between the throttle and cylinder head; the absolute pressure in the induction pipe, the so-called intake vacuum, is indicative of engine load and is used to control many engine-related functions

Induction pod: The port in the cylinder wall of a two-stroke engine which is used for the admission of the fresh charge into the cylinder

Induction stroke: A British term for the intake stroke, i.e., the phase of the 4-stroke cycle during which the intake valve is open and the piston descends from TDC to BDC, drawing air (in a diesel engine) or an air/fuel mixture (in a spark ignition engine) into the cylinder

Induction system

The system that brings the Fuel-air mixture to the Cylinders in a spark ignition engine. It includes the Carburetor or Fuel injection system, Air cleaner, Intake manifold, Intake ports, and Intake valves.
Air intake system used to cool the car.

Induction system intake configuration: See
Variable volume induction system intake configuration

Induction timing: See
Reed valve induction timing

Inductive: A joystick used on power wheelchairs

Inductive ignition system: An ignition system where the primary energy is stored in an inductor or an ignition coil

Inductive pick-up: See
Transistorized ignition with inductive pick-up

Inductive pulse pick-up: See
Magnetic pick-up assembly

Inductive reactance: Electromagnetic induction in a circuit creates a counter or reverse (counter) emf (voltage) as the original current changes. It opposes the flow of alternating current.

Inductive winding: See
Pick-up coil

Industrial Classification: See
North American Industrial Classification System
Standard Industrial Classification

Industrial Classification System: See
North American Industrial Classification System

Industrial tire: A heavy duty tire for use on forklifts, lowbed trailers, etc.

Industrial solid: A non-pneumatic tire (either entirely rubber or a regular tire with a solid rubber core to replace the tube), used most often on forklifts where the possibility of a flat tire is a constant problem.

Industrie Normen: See
Deutsche Industrie Normen

Industry: See
Automobile industry
Institute of the Motor Industry

Inert

Something that lacks a chemical action
A substance that exhibits no chemical activity, or does so only under extreme conditions
The property of the separators used between the plates of a battery

Inert arc welding: A family of arc welding processes in the fusion welding category. The welding pool is surrounded by a layer of inert shielding gas to keep oxygen from the weld; TIG welding is a typical inert arc welding process and is mainly used for repair work

Inert gas-arc welding: Surrounding the arc with a gas which does not react with the electrode and base metal and keeps the atmosphere away from the arc.

Inert gas system: A system of filling the space above the cargo oil in tankers with carbon dioxide from the boiler exhaust so as to prevent explosion.

Inert Gas Welding: See
Metal Inert Gas Welding

Inertia: That force which tends to keep a stationary object from being moved, and tends to keep a moving object in motion. Some effort is needed to get the object moving if it is stopped, and to stop an object if it is moving.

Also See
Moment of inertia
Polar moment of inertia
Thermal Inertia

Inertia drive: A Bendix drive which has a heavy piston moving along the shaft under the momentum of its own weight or inertia when the shaft turns inside it

Inertia fuel cut-off switch: See
Fuel pump shut-off switch

Inertial load: A load (flywheel, fan, or the like) which tends to cause the electric motor shaft to continue to rotate after the power has been removed

Inertia pinion: A Pinion used in an Inertia drive

Inertia reel: Generally the seat and shoulder belts are loose so that the drive and passenger can have the freedom to move forward to adjusting the instruments on the Dash, etc. However, when the vehicle decelerates quickly, as in a crash or panic stop situation, the occupants need to be restrained by the belts. The belts are locked by the inertia reel as it senses the rapid change of Deceleration.

Inertia reel seat belt: A 3-point seat belt with an automatic retractor reel. This type of seat belt allows the wearer to move while the vehicle is stationary or in steady motion but locks to restrain the wearer on sudden deceleration or impact

Inertia switch: A gravity actuated safety device which de-energizes the ignition, inhibits fuel pump operation, and activates the central locking system to open all door locks and close both the luggage compartment and fuel filler locks should the vehicle be subjected to heavy impact force.

Infant safety seat: See
Baby seat

Infiltration: Passage of outside air into building through doors, cracks around windows, etc.
Also see
Air Infiltration

Infinitely variable transmission: (IVT or CVT) Most Transmissions, whether Manual or Automatic have a fixed number of forward gears (from 2 to 10 or more). Belt driven vehicles (like snowmobiles) have an infinite number of positions of engagement. The infinitely variable transmission is sensitive to the changes in the throttle position and adjusts the Gear ratio accordingly. In this way, the most efficient Gear ratio is selected thus improving Fuel economy. Also called continuously variable transmission.

Infiniti

Click image for books on
Infiniti

The luxury automobile division of Nissan Motor Co., Ltd. established in 1989. Includes

FX35 (2003-07)
FX45 (2003-07)
G20 (1991-2002)
G35 (2003-08)
I30 (1996-2001)
I35 (2002-04)
J30 (1993-97)
M30 (1990-92)
M35 (2006-08)
M45 (2003-08)
Q45 (1990-2006)
QX4 (1997-2003)
QX56 (2004-07)

Infinity: An ohmmeter reading which indicates an open circuit in which no current will flow

Inflammable: Capable of being easily ignited and of burning quickly

Inflatable air-bag system: See
Supplemental restraint inflatable air-bag system

Inflatable restraint: See
Supplementary inflatable restraint

Inflate: To fill with air.
Also See
Hydrostatically inflate

Inflation: See
Load and inflation table
Over inflation
Reduced inflation
Underinflation

Inflation control seam: A system of inflation control seams on advanced air bags to control the inflation speed and inflation characteristics. Also called tear seam, whose negative connotations are perhaps inappropriate in a safety-related context

Inflation pressure: See
Tire pressure

Inflation table: See
Load and inflation table

Inflator: See
Emergency inflator

Inflator unit: An assembly beneath the folded air bag, consisting of a combustion chamber with a bridge igniter, a detonator, and a priming charge surrounded by the solid propellant, and a metal filter. A signal from the trigger unit causes the bridge igniter to fire the detonator, which in turn fires the priming charge and then the solid propellant. The nitrogen thus generated flows through a metal filter and reaches the air hag cleaned and cooled

Information centers: Visual displays which alert driver to certain vehicle conditions

Information System: See
Geographic Information System

Infrared: See
Non-dispersive infrared analyzer

Infrared analyzer: An instrument used to measure unburned hydrocarbons and CO discharged from a vehicle exhaust pipe.

Also See
Non-dispersive infrared analyzer

Infrared lamp: Electrical device which emits infrared rays; invisible rays just beyond red in the visible spectrum.

Infrared radiant drier: An infrared lamp which accelerates the drying of large areas of fresh paint

Infrared rays: Heat rays which emanate from both the arc and the welding flame.

Infrared remote control: (IR) the control of an operation by means of an infrared beam transmitted to a receiver (e.g., garage door, central locking, car alarm system, etc.)

Ingot: Steel (and other metals) formerly in a molten state, transferred to an rectangular mold to solidify.

Ingress: Entry, as in "sealant is used to prevent the ingress of moisture".

Inherently Low-Emission Vehicle

(ILEV)

Any vehicle that is certified to meet transitional low-emission vehicle standards established by the CARB and does not emit any evaporative emissions.
A vehicle meeting EPA's CFV ILEV standards. Tailpipe standards may be HC LEV with ULEV NOx, ULEV, or ZEV and includes the additional requirement that evaporative emissions be 2 grams per test over the full test procedure and 5 grams per test without the use of any auxiliary emission control devices. ILEVs will be dedicated AFVs in most cases. Dual-fuel vehicles will be considered ILEVs only if both fuels meet the standard. (Very low-volatility gasoline may also meet the standard.) ILEVs are exempt from certain transportation control measures, including HOV lane restrictions. This standard is voluntary and need not be adopted by states.

Inhibit: To hinder or to prevent

Inhibitor

A substance which prevents chemical reaction such as corrosion or oxidation.
A substance added to oil, water, gas, etc., to prevent action such as foaming, rusting, etc. The opposite is Catalyst.

Also See
Corrosion inhibitor
Reverse inhibitor valve
Rust inhibitor
Vanadium Inhibitor

Inhibitor switch: See
Starter inhibitor switch

Inhibitor valve: See
Reverse inhibitor valve

Initial enrichment: Average enrichment for a fresh fuel assembly as specified and ordered in fuel cycle planning. This average should include axial blankets and axially and radially zoned enrichments.

Initial stopping speed: Speed of a motor vehicle at the start of brake application

INJ: Acronym for Injector Valve which injects fuel into inlet, duration times commanded by the PCM. INJ 1 to INJ 10 refers to Fuel Injectors 1 to 10

Inject: To introduce a fluid (into something) under pressure

Injected engine: See
Fuel-injected engine

Injection: See
Air injection
Central Fuel Injection
Digital Fuel Injection
Direct injection
Electronic fuel injection
Electronic Gasoline Injection
Fuel injection
Fuel injection engine
Fuel injection pump
High speed direct injection
Indirect injection
Indirect injection engine
L-jetronic fuel injection system
Multi-point Fuel Injection
Multi-point injection
Multiport Fuel Injection
Port fuel injection
Programmed Fuel Injection
Pulsed Injection
Reaction injection molding
Reinforced reaction injection molding
Sequential Electronic Fuel Injection
Sequential fuel injection
Single point injection
Solid injection
Throttle body fuel injection
Tuned Port Injection
Water injection
Wax injection

Injection burner

Two types:

Bunsen Type: A burner employing the energy of a jet of gas to inject air for combustion into the burner and mix it with the gas.
Atmospheric Type: A burner in which the air at atmospheric pressure is injected into the burner by a jet of gas.

Injection engine: See
Fuel injection engine
Indirect injection engine

Injection fuel: In Bosch CIS, the pressure of the fuel in the lines between the differential-pressure valves and the injectors. Also called Injection pressure

Injection lag: The time interval (expressed in crankshaft degrees) between the nominal start of injection pump delivery and the actual start of injection at the nozzle

Injection manifold: See
Air injection manifold

Injection-molded: Produced by an Injection molding machine or process

Injection molding: A method for the fabrication of thermoplastic materials. The viscous resin is squirted, by means of a plunger, out of a heated cylinder into a water-chilled mold, where it is cooled before removal. This method is also used with thermosetting molding powders.

Also See
Reaction injection molding
Reinforced reaction injection molding

Injection moulding: British term for Injection molding

Injection molding machine: A machine used to produce preformed plastic body panels

Injection period

The length of time for which fuel is sprayed into the intake ports or combustion chamber during fuel injection. It is controlled by the electronic control unit. The injection period depends mainly on engine speed and the amount of induced air and is normally between approx. l.5 and 9 milliseconds
The time, measured in degrees of crankshaft rotation, between the beginning and end of injection. On engines with hydromechanical injection systems, it is controlled by the opening and closing of ports in the injector body or by the action of a plunger forcing fuel out of a cup. On electronic injection systems, it is determined directly or indirectly by the action of a solenoid valve.

Injection pressure: In Bosch CIS, the pressure of the fuel in the lines between the differential-pressure valves and the injectors. Also called Injection fuel

Injection pump: A pump which receives fuel from the fuel tank (often through the fuel-feed pump in the case of diesel engines) and delivers it under pressure to the injectors.

Also See
Distributor Injection Pump
Fuel injection pump
Rotary Injection Pump

Injection pump governor: Device which controls fuel deliver to limit the minimum and maximum engine speeds, as well as intermediate throttle positions

Injector opening pressure: The point at which injection pump fuel pressure overcomes nozzle valve-spring resistance, or combustion chamber pressure, so that fuel is injected into the pre-combustion chamber

Injection reaction: See
Air injection reaction system

Injection system: See
Air injection system
Continuous injection system
L-jetronic fuel injection system
Steam injection system

Injection valve: See
Injector

Injector: A solenoid or pressure-operated fuel delivery valve (used in a Fuel injection system) that squirts or injects a measured amount of Gasoline into the Intake manifold in the vicinity of the Intake valve. In a Diesel engine fuel is injected directly into the Cylinder. In a CIS, the injectors atomize the continuous flow of fuel injected under pressure into the intake ports of the engine; a valve in the injector nozzle stops the flow of fuel when fuel pressure drops below a certain point; in a CIS, the quantity of fuel is regulated by the fuel distributor's metering unit; in other fuel injection systems, the fuel system delivers a constant supply of fuel at a constant pressure to the injector, and an electronic sensing and control system produces electrical current pulses of appropriate duration to hold open the injector solenoid valves; as fuel pressure is held constant, varying the pulse duration increases or decreases the amount of fuel passed through the injectors.
Also See
Cold start injector
Fuel injector
Fuel injector nozzle
Pencil-type Injector
Unit Injector

Injector nozzle: The tip of the injector, either of multi-hole design for direct injection or pintle design for indirect injection.

Also See
Fuel injector nozzle

Injury: See
Bodily injury
Whiplash injury

Inlay: Partial pavement removal and replacement, normally used to eliminate ruts in roadway surface.

Inlet: An opening in the face of, and under, a curb allowing water to enter the drainage system.
Also see
Carburetor Fuel Inlet
Primary Air Inlet

Inlet cam: The cam responsible for the actuation of the inlet valve in DOHC engines

Inlet camshaft: The cam responsible for the actuation of the inlet valve in DOHC engines

Inlet line: A pipe or hose on the intake side of a component, through which a fluid is supplied by gravity from a reservoir or tank located at a higher level; e.g., from coolant expansion tank to radiator, or from brake fluid reservoir to master brake cylinder

Inlet manifold: British term for Intake manifold describing the component which guides the intake air to the cylinder head intake ports; usually an aluminum casting or a GRP molding, with one intake opening and as many outlets as there are cylinders in the engine

Inlet manifold heater: See
Flame glow plug

Inlet over exhaust: Valve layout used on some early machines in which the exhaust valve was mounted to the side of the engine and the mechanically operated inlet valve was positioned above the exhaust

Inlet over exhaust engine: (IOE engine) A British term for intake over exhaust engine describing an engine design used on early cars. Also called F-head engine The intake and exhaust valves are arranged vertically in a lateral chamber of the combustion chamber and face one another; the side valve (usually the exhaust) is actuated directly by the camshaft, which usually rotates in the cylinder block; the overhead valve (usually the intake) is located in the cylinder head and actuated via a pushrod and rocker arm

Inlet pipe: See
Intake manifold.

Inlet port: A British term for Intake port

Also See
Filler port

Inlet sock: A coarse fuel filter in an older fuel tank, designed to remove only very large dirt particles; it can last the life of the car. The sock is made of saran, so water won't enter until the sock is entirely engulfed in water.

Inlet stroke: A British term for Intake stroke

Inlet System: See
Heated Air Inlet System

Inlet tract: A British term for Intake tract

Inlet valve: A valve that opens to allow the fuel/air mixture to enter the combustion chamber. A British term for Intake valve
Also see
Air Inlet Valve

Inlet valve closes: (IVC) A British term for Intake valve closes

Inlet valve opens: (IVO) A British term for Intake valve opens

In-line: Engine layout in which the cylinders are arranged in a row, and in-line with the wheels of the machine

Inline compressor: Two-cylinder compressor with the pistons arranged side-by-side, like a York or Tecumseh

Inline engine: An engine in which the cylinders occur in a single row with the crankshaft running along the bottom.
See
In-line engine.

In-line engine: An engine in which all the Cylinders (usually three or more) are arranged in a straight row (either vertically or slanted). The pistons drive a common crankshaft. Also called a straight engine.

In-line five-cylinder engine: In-line five-cylinder engine

An engine type that was first introduced by Mercedes-Benz in 1974. Its advantage is that it produces more power than a four cylinder but takes up less space than an in-line six.

In-line four-cylinder engine: In-line four-cylinder engine

An engine type often found in lightweight economy and sports cars. It is short enough to be placed sideways in some front-wheel-drive models. Most fours vibrate noticeably, especially at low engine speeds.

Inline fuel filter: See
In-line fuel filter.

In-line fuel filter: In-line fuel filter

A Fuel filter which is placed within the fuel pipes or hoses coming from the Fuel tank or Fuel pump. It is made of pleated paper or nylon mesh and encased in a transparent plastic or glass housing. To install it, a segment of the fuel line is cut and removed. The filter is inserted to replace the removed segment of the fuel line.

Inline fuel heater: A heater which is integral to the fuel line on a diesel engine fuel prior to the filter to keep paraffin crystals from stopping fuel flow. The heater warms the fuel by -7°C

In-Line Injection Pump: An Injection pump with a separate cylinder and plunger for each engine cylinder. Each plunger is rotated by a rack to determine metering via ports in the body of the pump and helical cuts on the pump plungers. The plungers are driven off a camshaft, which usually incorporates a centrifugal or electronically controlled timing advance mechanism.

In-line power steering: Power-assisted steering applied within the steering box or rack

In-line pump: A pump whose suction and discharge branches are arranged in line for direct installation into the pipework; special foundations are unnecessary, and the absence of shaft couplings eliminates alignment problems

In-line six: An engine with six cylinders in a row
Also see
In-line six-cylinder engine

In-line six-cylinder engine: In-line six-cylinder engine

An engine type that is longer and heavier than four or five cylinder in-line engines, but are generally smoother and more powerful. Before the era of front-wheel drive vehicles, this six-cylinder engine was the common entry level engine. Most were not mounted transversely and thus allowed a lot of working room on either side of the engine. Chrysler Corporation slanted its six-cylinder at a 30° angle which lowered its center of gravity.

Inline three: An engine with 3 cylinder in a row

In molded: A process of manufacturing a helmet in which the outer shell is pressed on to the inner shell so that the helmet is more resistant to wear and tear.

Innage: Space occupied in a product container.

Inner attachment face: The part of the brake disc directly fixed to the wheel hub

Inner cap nut: (sleeve nut) A securing device on a dual mounted disc wheel type where it threads directly on the stud and holds the inner wheel in place against the hub.

Also See
Outer cap nut

Inner cone: A small, innermost part of the flame at the tip of a blowtorch, the shape of which indicates the torch adjustment

Inner Construction: All the braces, brackets, panels of the vehicle's body which give it strength. In contrast with Outer construction

Inner cylinder: The working chamber of a double-tube shock absorber

Inner dead center: See
Top dead center

Inner fender panels: The vertical panels mounted to the left and right of the engine bay that provide the mounting flanges for the fenders and the top suspension attachment

Inner headlight: The inner one of twin headlights usually for high beam only. The opposite is Outer headlight

Inner liner: The innermost layer of a tubeless tire which provides an airtight barrier

Inner mounting face: See
Inner attachment face

Inner race: Bearing Race

The inner track or ring that provides a contact surface for the balls or Rollers in a bearing.

Inner sill: The hidden part of the sill located behind the outer sill panel, which serves to reinforce the underbody. It is also called longitudinal member or side member

Innerspring seat: A sturdy, sofa-like seat design using spring coils as damping elements; used mainly by Mercedes-Benz

Inner tube: A doughnut-shaped rubber or latex air chamber which normally is inserted into a non-tubeless tire to hold pressurized air. It contains an air valve to inflate the tube.

Innova®: A fabric used in clothing to provide comfort in all seasons as well as moisture transfer. Innova's hydrophobic qualities facilitate movement away from the skin. Innova does not retain odor and resists damage from perspiration. Innova has the lowest thermal conductivity of any fiber and possesses the lowest moisture regain of any fiber for shorter drying time.

Inorganic

Not organic, i.e., composed of matter other than animal or vegetable. In technical terms, any substance that is not a carbon compound (with the possible exception of the oxides and sulfide of carbon)
Pertaining to or composed of chemical compounds which do not contain carbon as the principal element, i.e., matter which does not come from plants or animals. The opposite is Organic

In-place recycling: See
Hot in-place recycling

Input: See
Gearbox input shaft
Reference input
Step steering input

Input shaft: The shaft delivering power into a mechanism. The shaft from the Clutch into the Transmission is the transmission input shaft. Also called Clutch shaft.

Also See
Gearbox input shaft
Transmission input shaft

Input Signals: See
Powertrain Input Signals

Input variable: The object of measurement and control; e.g., pressure, temperature, etc.

Insert

When referring to bearings it indicates a replaceable shell-type bearing made to extremely close Tolerances and generally used for Main bearings and Connecting rod bearings.
When referring to valves it indicates replaceable Valve seats made of hard, heat-resisting metal that are screwed or shrunk into the Cylinder head.
When referring to Spark plugs it indicates replaceable threads which are installed into damaged Spark plug holes so that Spark plugs can be installed. Sometimes known by the trade name Heli-coil.
Piston Liners or Cylinder sleeves.
As a verb, it is the technique of permanently joining plastics and other materials, e.g., embedding steel clips in a molded plastic cover. Molded-in inserts are placed into the injection mold cavity so that the melt flows around them during injection; post-molding inserts may be installed by press-fit or ultrasonic methods.

Also See
Bumper insert
Precision insert bearing
Threaded Insert
Thread insert
Top ring groove insert
Valve seat insert

Insert bearing: A removable, precision made bearing which insures specified Clearance between bearing and shaft.

Also See
Precision insert bearing

Insert socket: A socket for use with a slogging ring wrench which raises the wrench above the surface, thus preventing hammer damage to floor or equipment

Insert tap: See
Spark plug insert tap

Inside caliper: A machinists' caliper used to check inside dimensions.

Also See
Caliper.

Inside calipers: A machinists' caliper used to check inside dimensions.

Also See
Caliper.

Inside corner weld: Two metals fused together; one metal is held 90 degree to the other. The fusion is performed inside the vertex of the angle.

Inside diameter: (ID) The internal diameter of a cylinder or tube

Inside pry spoon: A specialized pry bar designed to reach behind brackets and reinforcing bars to pry the metal. The pointed end of the inside pry spoon is placed at the high point of a dent, which is then forced out

Inside spring caliper: An inside caliper with spring for accurate setting

Insolation: Exposure to the rays of the sun

Inspection: A type of examination which serves to evaluate the operating condition of a component or system; the inspection may identify the need for servicing or repair.

Also See
Rust inspection

Inspection and Maintenance Programs: (IM) In-use emission testing programs, primarily for passenger cars, used by some U.S. states to identify vehicles that cause excessive emissions which contribute to air pollution.

Inspection lamp: A British term for a Trouble-shooting light.

Inspection lot: Certain quantity of a particular item chosen at random for quality testing

Inspection mirror: A tool used to inspect hidden areas on automotive parts. It consists of a long rod (sometimes telescoping) with a small mirror at one end.

Inspection pit: A pit in the floor of a garage providing working space underneath a vehicle

Instability: See
Azimuthal Power Instability

Install: To put something in position ready for use

Installation: Putting something in position ready for use. The opposite is removal
Also see
Non-code Installation

Installed height

The height at which something is placed in position.
The spring's measured length or height, as installed on the cylinder head. Installed height is measured from the spring seat to the underside of the spring retainer

Also see
Load At Installed Height

Installed market: See
Mechanic installed market

Installed nameplate capacity: See
Generator nameplate capacity

Installer

An automotive mechanic whose sole responsibility is to install accessory equipment into a vehicle (e.g., radio, antenna, CD player, GPS)
A tool used to install a component in place

See
Hose clamp installer
Hose clip installer
Valve stem seal installer

Instant spare: An emergency inflator

Institute For Highway Safety: See
Insurance Institute For Highway Safety

Institute of the Motor Industry: (IMI) British organization for managers in the motor industry

Instrument: Used broadly to denote a device that has measuring, recording, indicating, and/or controlling abilities.
Also see
Blind Flying Instruments

Instruments and controls: A general term covering all gauges, indicators, switches, regulators, and buttons

Instrument cluster

An array of separate gauges in one housing; a major component of the instrument panel including analog or digital instruments and indicators, but no controls except for the trip mileage reset button on some cars.
Several gauges integrated into one instrument, making one unit combining several functions, e.g., engine temperature, oil pressure and fuel gauge; if one gauge fails, the entire instrument cluster must be replaced

Instrument panel: The panel below the windshield and/or the cowl top panel and attached to the dash panel or fire wall, and which accommodates the instruments and controls. Also called Dash, Dashboard, or Fascia

Insulate: To cover with non-conducting material, so as to prevent the transmission of heat, electricity, or sound

Insulated trailer: A trailer designed for transporting commodities at controlled temperatures, usually provided with refrigerating and/or heating equipment.

Insulating cap: The insulated top of the coil tower

Insulating tape: PVC tape (usually black) for wrapping around electrical connections

Insulation

Any material which does not conduct electricity. It is used to prevent the flow or leakage of an electrical Conductor.
Any material which does not readily conduct heat. Used to keep heat or cold out of something.
The process of insulating.
(INSUL) In an electric motor, usually classified by maximum allowable operating temperature
class A 105°C
class B 130°C
class C 155°C
class H 180°C

Also see
B-class Insulation
Electric Insulation
Thermal Insulation

Insulation, electric: Substance which has almost no free electrons.

Insulation, thermal: Material which is a poor conductor of heat; used to retard or slow down flow of heat through wall or partition.

Insulator

A unit made of a material that will not conduct electricity. The electricity in a copper wire covered with a plastic sleeve (insulator) cannot penetrate the sleeve.
A material that prevents or slows the transfer of heat from one area to another
A material which tends to resist the flow of electric current

Also See
Cap-and-pin Type Insulator
Cascading Of Insulators
Ceramic Insulator
Spark plug insulator

Insulator nose: The tip of a spark plug
Also see
Projected Core insulator Nose

Insulator tip: The tip of a spark plug

Insurance: See
Automobile insurance
Car insurance
Collision insurance
Comprehensive insurance
Gap insurance
Motor insurance
No fault insurance

Insurance Institute for Highway Safety: (IIHS) A US body for determining the crashworthiness of vehicles in order to determine insurance costs.

Insurance premium: A regular payment for an insurance policy

Int: Abbreviation for interior.

INT

Acronym for Integrator (replaced by ST FUEL TRIM)
Abbreviation for Intermittent duty cycle

Intake: See
Air Cleaner Intake
Air intake
Cold air intake
Heated intake
Intake manifold
Intake port
Intake tract
Intake stroke
Intake valve
Ram intake manifold

Intake air temperature sensor: A sensor located in the induction system that provides an electrical output proportional to the temperature of the air or air/fuel mixture

Intake cam: The cam responsible for the actuation of the inlet valve in DOHC engines

Intake camshaft: The cam responsible for the actuation of the inlet valve in DOHC engines

Intake charge: The mixture of fuel and air that flows into the engine.

Intake configuration: See
Variable volume induction system intake configuration

Intake manifold: Intake manifold

The connecting tubes between the base of the Carburetor and the Port openings to the Intake valve or intake ports. The air-fuel mixture travels from the Throttle body into a chamber called the Plenum which feeds individual tubes (called runners) which lead to the individual intake port. Its purpose is to transfer the Air-fuel mixture to each Cylinder. It is usually an aluminum casting or a GRP molding, with one intake opening and as many outlets as there are cylinders in the engine. Also called inlet pipe. The British term is inlet manifold.
Also See
Ram intake manifold
Variable intake manifold

Intake manifold heater: See
Flame glow plug

Intake over exhaust engine: (IOE engine) An engine design used on early cars. Also called F-head engine. The intake and exhaust valves are arranged vertically in a lateral chamber of the combustion chamber and face one another; the side valve (usually the exhaust) is actuated directly by the camshaft, which usually rotates in the cylinder block; the overhead valve (usually the intake) is located in the cylinder head and actuated via a pushrod and rocker arm

Intake pipe: The duct, typically an alloy manifold, between the throttle and cylinder head; the absolute pressure in the induction pipe, the so-called intake vacuum, is indicative of engine load and is used to control many engine-related functions. The British term is induction pipe

Intake plenum: See
Plenum chamber

Intake port

Intake port

The passage in the Cylinder head which connects the Intake manifold to the Intake valve through which the Fuel-air mixture proceeds on its way to the Cylinders. The British term is inlet port.
The passage through which brake fluid flows in the master cylinder from the reservoir to refill the low-pressure area ahead of the cup on the return stroke

Also See
Filler port

Intake stroke: Click image to supersize

In a Four-stroke cycle engine, it is the Piston's first stroke down in pulling fuel and air into the Combustion chamber as it causes a partial Vacuum. The phase of the 4-stroke cycle during which the intake valve is open and the piston descends from TDC to BDC, drawing air (in a diesel engine) or an air/fuel mixture (in a spark ignition engine) into the cylinder. The British term is induction stroke

Intake tract: A branch of the Intake manifold leading to an Intake port.

Intake valve: Intake valve

The Poppet valve that opens to permit the fuel mixture into the Cylinder. It closes during the compression and combustion strokes. Some engines have more than one intake valve to each cylinder. The British term is inlet valve.

Intake valve closes: (IVC) A mark on a valve-timing diagram.

Also See
EVC

Intake valve opens: (IVO) A mark on a valve-timing diagram.

Also See
EVO

In-tank fuel pump: An electric fuel pump that keeps pressure in the fuel line prior to the main fuel pump to prevent vapor lock.

Integra: Click logo for books on
Integra

A model of automobile from Acura

Integral: An essential component of something.

Also See
Integral part of.

Integral ABS: An ABS in which the power booster and components of the standard and ABS brake systems form a single hydraulic unit.

Integral alternator/regulator: (IAR) a type of regulator mounted at the rear of the alternator

Integral backpressure transducer EGR valve: Combines inputs of exhaust backpressure and EGR ported vacuum into one unit. Requires both inputs to operate on vacuum alone there are two common designs Poppet and tapered pintle

Integral body and frame construction: See
Unitary construction

Integral collector storage: (ICS) A solar thermal collector in which incident solar radiation is absorbed directly by the storage medium.

Integral color anodizing: An anodizing process in which the color is produced by using special electrolytes

Integral equipment: Any device or system that is designed for a vehicle and installed in it by the manufacturer, rather than being added on to a finished vehicle at a later date.

Integral frame: See
Unitary construction

Integral fuel filter: A Fuel filter which is part of the Fuel pump or part of the Carburetor rather than one that is attached to a fuel line (In-line fuel filter).

Integral horsepower motor: In terms of horsepower, an Open enclosure electric motor built in a frame having continuous rating of 1 hp or more at 1700-1800 rpm. In terms of size, an integral hp electric motor is usually greater than 9 inches in diameter, although it can be as small as 6 inches

Integrally molded linings: Disc brake pad sets that have the linings cured integrally with the pad plates.

Integral molded seat: A seat with integrated 3-point seat belt

Integral part of: A necessary part of something, e.g., the Cam lobe is an integral part of the Camshaft.

Integral-type power assisted steering: See
In-line power steering

Integral-type power steering: See
In-line power steering

Integral vacuum booster: A vacuum booster that installs between the brake pedal and the master cylinder. Integral boosters are actuated by brake pedal movement.

Integrated: See
Thick Film Integrated

Integrated child safety seat: A fold-down child safety seat located in the center of the rear seats that is part of the original car. This seat includes seat belts, and are generally not as good as aftermarket safety seats. They are not as adjustable or comfortable. There is generally little or no side protection and the child normally must sit with his legs sticking straight out. When not in use, the seat can be folded away, much like an armrest.

Integrated child seat: A rear seat that can be converted into a child seat.

Also See
Integrated child safety seat

Integrated circuit

(IC)

A circuit that incorporates multiple transistors and other semiconductors to a single circuit, sometimes called a chip.
A complete electronic circuit consisting of numerous transistors and other solid state devices, and formed on a single silicon semiconductor chip.

Integrated circuit board: Electronic circuit made from transistors, resistors, etc., all placed into a package referred to as a chip, since all circuits are on one base of semiconductor material.

Integrated Direct Ignition System: (IDI) A distributorless ignition system consisting of two separate ignition coils, an ignition module, a secondary conductor housing mounted to an aluminum cover plate, a crankshaft sensor, and electronic spark timing

Integrated roll cage: The cage or framing of the car serves the dual purpose of protecting the passenger while also creating a place to hang all the car's components -- engine, steering, sheet metal, etc. An integrated roll cage is one that is claimed to be especially safe and designed to protect the passenger in the case that the car rolls. It is called integrated because it is part and parcel of the overall framing for the car's components and thus sturdier.

Integrated safety belts: Consist of a shoulder belt and a lap belt. Whereas the cars of the 60s had the option of being ordered without seat belts, today's cars have an integrated safety belt as standard equipment.

Integrated system: An anti-lock brake system with the brake booster and hydraulic modulator integrated into a unit with the master cylinder

Integrator: See
Capacitance Integrator

Intellectual property rights: (IPR) The right to possess or control the use of intellectual property, such as trademarks, copyrights, patents and trade secrets.

Intelligent Transportation Systems: (ITS) A traffic monitoring system that uses electronics to communicate with motorists. Examples include variable message signs and video traffic cameras.
See
Intelligent Vehicle Highway Systems

Intelligent Vehicle Highway Systems

(IVHS) Blanket term for a wide array of technologies, including electronic sensors, computer hardware and software and radio communications. The purpose of IVHS is to increase efficiency of use of existing highways, reducing travel time, fuel consumption, air pollution and accidents. There are five functional areas:

Advanced Public Transportation Systems (APTS)
Advance Traffic Management Systems (ATMS)
Advance Traveler Information Systems (ATIS)
Advanced Vehicle Control Systems (AVCS)
Commercial Vehicle Operations (CVO)

A more recently coined term, Intelligent Transportation Systems, encompasses both IVHS and modes of transportation other than highway, such as rail.

Intel-plate: The disc between the driven plates in a twin plate clutch

Intensify: To increase or concentrate, such as to increase the Voltage of an electrical Current.

Intensity: See
Carbon Intensity
Field intensity
Heat Intensity

Interactive wishbone: The patented suspension system used on the front of the new Lotus Elan which maintains precise suspension geometry without transmitting undue road harness to the passengers. The result is the elimination of torque steer and bump steer, and a very comfortable ride.

Inter-axle differential: Gear device equally dividing power between the axles and compensating for unequal tire diameters. Also called Center differential

Inter-cable adjuster: An adjuster built into some parking cables that allows the outer housing to be made longer or shorter to adjust the parking brake.

Intercell connector: A lead strap or connector that connects the cells in a battery

Inter-cell link: An electric conductor that carries electric current between the adjacent cells of a battery

Interchangeable head torque wrench: A wrench that does not have the usual square drive for use with sockets, but is designed to accept special interchangeable heads

Interchannel competition: The rivalry between different channels of the distribution system. For example, independent retailers competing with manufacturers' outlets.

Intercity bus: A transportation vehicle designed for high speed, long distance travel; equipped with front doors only, high backed seats, and usually restroom facilities.

Intercoastal: Domestic shipping routes serving more than one coast.

Intercoat adhesion failure: A situation in which one coat of finish peels off or can easily be stripped off with masking tape from another layer underneath. This may be caused by excessive bake time of coatings, resulting in too hard a finish, poor flatting of coats, providing poor keying of coats, or very low film thickness

Intercooler

A device which cools the air entering the Carburetor or Fuel injection system. Colder air has more oxygen molecules than warm air. Thus cooler air gives more power and better Fuel economy. An intercooler looks like a Radiator. It contains large passages for the intake flow, and uses either outside air or water directed over it to lower the temperature of the intake flow inside. Also called a charge-air cooler or Charge cooler. Compare Aftercooler.
A heat exchanger for cooling gas between stages of a multistage compressor with a consequent savings in power.

Also see
Air-to-air Intercooler

Intercooling

The temperature reduction of the charge air between compressor and engine
Cooling the engine intake air after the turbocharger and prior to introduction into the cylinder.

Intercostal: A structure made in separate parts; between each floor, frame or beam, etc instead of made in one continuous length spanning all the floors, frames, or beams

Intercrystalline corrosion: A small outbreak of rust occurring along crystal boundaries of metals or alloys

Interest: See
Net interest rate

Interest rate: See
Base interest rate
Buy at end-of term interest rate
Net interest rate

Interference

Difference in angle between mating surfaces of a valve and a Valve seat.
The noise from the ignition system that affects radio and TV reception. Suppressors are used to minimize interference and on modern vehicles the main suppressors are the spark plug leads.

Also See
Radio frequency interference

Interference 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 Drive fit.

Intergovernmental Panel on Climate Change: (IPCC) A panel established jointly in 1988 by the World Meteorological Organization and the United Nations Environment Program to assess the scientific information relating to climate change and to formulate realistic response strategies.

Intergranular corrosion: A small outbreak of rust occurring along crystal boundaries of metals or alloys

Interior: The inside of a vehicle

Interior light: The Courtesy light which illuminates when the doors are opened or when an interior switch is activated.

Interior light switch: There are two types of switches which turn on the interior lights One is located on the door posts and is activated when the door is opened or closed. The other is found on the dash and may be incorporated into the headlight switch.

Interior mirror: The rear-view mirror located centrally near the top of the windshield.

Also See
Exterior mirror

Interior noise level: The level of noise inside the vehicle, typically in the range from 45-90 dBA from idle to full throttle; at 70 mph between 66-87 dBA

Interior payload: The amount of weight that a vehicle can carry. The capacity of the usable area in the vehicle's interior. It is defined by cubic feet. This includes the seating area for passengers as well as the cargo space

Interior trim: The panels, linings, decorative facings, upholstery, and covers inside a vehicle

Interleaf friction: The friction between individual leaves of a leaf spring

Interlock

To fit gear train members together.
A device in a change-speed gearbox which prevents two gears from being engaged at the same time.
A control to prove the physical state of a required condition and to furnish that proof to the safety shutoff device circuit.

Also See
Accelerator interlock
Clutch starter interlock
Parking interlock
Shift interlock
Starter interlock

Interlock Switch: See
Clutch Interlock Switch

Intermediary: Firm or organization that operates between the producer of the goods and the end purchaser. Thus, the members of the distribution channel noted above are intermediaries or "middlemen".

Intermediate: Between two things or two extremes

Intermediate car: A designation no longer used because even full-size cars are now about the size of what was the compact car. In 1970, for instance, a Chevrolet Impala was a full-size car, a Chevelle was an intermediate, a Nova was a compact. When cars smaller than the Nova came out (i.e., Chevette), they were called sub-compacts.

Intermediate coat: Any coat of paint between the first coat (primer) and last coat (finish)

Intermediate drive plate: A disc between the driven plates in a twin plate clutch

Intermediate gear: Any gear in the auto Transmission between first and high. Usually refers to second or third gears

Intermediate grade gasoline: A grade of unleaded gasoline with an octane rating intermediate between Regular and Premium. Octane boosters are added to gasoline to control engine pre-ignition or knocking by slowing combustion rates.

Intermediate hold: A term dating from the early days of three-speed automatic transmissions; today represented by the position 2 on the selector quadrant

Intermediate lever: A parking brake linkage lever (other than the parking brake pedal, lever, or handle) used to increase parking brake application force.

Intermediate plate: A disc between the driven plates in a twin plate clutch

Intermediate rim taper: A rim with one tapered bead seat of 5° at the fixed flange.

Intermediate rod: See
Relay rod

Intermediate shaft: A rotating shaft joining two other shafts

Intermetallic compound: An alloy of two metals in which a progressive change in composition is accompanied by a progression of phases with varying crystalline structures

Intermittent: Not constant but occurring at intervals.

Intermittent duty cycle: (INT) An electrical motor which never reaches normal operating (equilibrium) temperature but is permitted to cool down between operations is operating under intermittent duty conditions. Compare Continuous Duty Cycle

Intermittent cycle: Cycle which repeats itself at varying time intervals.

Intermittent fault: A problem which comes and goes (and annoyingly never occurs when the car is taken in to the garage for repair!)

Intermittent weld: Joining two pieces and leaving unwelded sections in the joint.

Intermittent wiper control: A device which operates the wipers at preset intervals; typically adjustable from 2 to 40 seconds. It usually includes a mist action which makes only one swipe and then stops. Most often used in conditions of light drizzle or snow, mist, and spray from other vehicles

Intermittent operation: A system which is not activated in a regular pattern, but with specified delays.

Intermodal Container: A cargo container designed for high-speed transfer of cargos between different transportation modes. Typically seen around harbor ports, railway yards, and cargo storage facilities.

Intermodal Surface Transportation Efficiency Act of 1991: (ISTEA) An omnibus act that further integrates the national intermodal surface transportation system and authorizes funds for highway construction, highway safety programs, and mass transit programs. ISTEA seeks a national intermodal surface transportation system that is economical, energy efficient, and environmentally sound. Section 1008 of the ISTEA establishes the Congestion Mitigation and Air Quality Improvement Program which can provide funds to support alternative-fuel and alternative-fuel vehicle programs.

Intermodal transportation: Transportation that involves the interchange between transportation modes, such as automobiles, mass transit such as buses and railway. Intermodal transportation enables people and goods to be consolidated into larger groups that can be transported at lower costs. In addition to reducing costs, it enables greater logistic flexibility than can also reduce congestion and travel time.

Internal bowl vent: A tube designed to vent excess fuel vapors from the fuel bowl back into the carburetor during acceleration and cruising conditions

Internal circlip pliers: A special pliers with pointed jaw tips for the installation and removal of internal circlips

Internal Collector Storage: (ICS) A solar thermal collector in which incident solar radiation is absorbed by the storage medium.

Internal combustion engine: (ICE or IC) An engine that burns fuel within itself as a means of developing power (unlike an External combustion engine such as a steam engine). Although the term internal combustion engine covers all types of reciprocating and rotary engines, it is typically used with reference to four-stroke gasoline and diesel engines

Internal damage: Injury to the body shell that is not usually visible from the outside. Such damage is often caused by rust from the inside of panels and fenders, so the damage becomes visible only in an advanced state of decay

Internal diameter: See
Inside diameter

Internal gear: An internally toothed Annular gear

Internal gear pump: A gear pump which has one rotor with internally cut teeth meshing with an externally cut gear idler; a crescent-shaped partition is used to prevent liquid from passing back to the suction side of the pump; a typical oil pump, characterized by quiet operation and high capacity

Internal manifolding: A system with a self-contained reactant delivery system similar to a boxed fuel cell system that would only require connections to the reactant tanks to become operational.

Internal micrometer: A Micrometer for inside measurements such as distances between two parallel surfaces or inside diameters of cylinder and main bearing bores

Internal mix air cap: A special type of air cap for spray guns. Air and material are mixed inside the gun and are ejected through a single orifice. This design is used only for pressure-feed guns, primarily for spraying heavy viscous materials. Compare External mix air cap

Internal reforming: See
Direct internal reforming.

Internal resistance: The resistance inherent in a voltage source, such as a battery. The internal resistance of a battery is made up of several individual resistances, e.g., between the plates and the electrolyte, the plate resistances, the resistance of the electrolyte to ion flow, and internal connectors

Internal Resistance Loss: See
Cell Internal Resistance Loss

Internal snap ring: A split ring held in place by its own tension within a groove cut around the bore of a hole. Compare External snap ring.

Internal thread: The thread on the inside of a nut or similar into which the external thread of a bolt or screw fits. Also called female thread

Internal tooth lock washer: Internal tooth lock washer

A lock washer with serrations on the insi