DICTIONARY OF AUTOMOTIVE TERMS - "Ex"

Examination:

See:
metallographic examination

Exc:

Abbreviation for "excellent," as in exc condition.

Excalibur:

A vehicle brand of which the 1965-69 model II Series I are milestone cars.

Exchange engine:

A replacement engine which is provided in exchange for a worn engine while the original engine is being rebuilt

Exchange process:

See:
charge exchange process

Exchanger:

See:
heat exchanger.

Excelsior:

The 1925-1948 models with required application are classic cars.

Excitation current:

The electric current in the shunt field of an electric motor resulting from voltage applied across the field

Excitation winding:

Field winding

Excite:

To pass an electric current through a unit such as the field coils in the generator.

Exciter coil:

A primary coil which provides stepped up voltage to a second coil.

Exciter winding:

Field winding

Excluder:

See:
draught excluder

Ex-demonstrator:

A vehicle which had been used as a demonstrator and is now available for sale

Exducer:

The outermost section of a turbine wheel, used to purge the turbine of exhaust gases

Executive car:

A large, powerful luxury car considered suitable for a business executive

Exempt Carrier:

A company which transports commodities exempted from Interstate Commerce Commission (ICC) economic regulation.

Exfiltration:

Slow flow of air from the building to the outdoors.

Exhaust:

1. To expel spent fumes.
2. The spent fuel after combustion takes place in an internal combustion engine. Sometimes it refers to the exhaust system.

Also See:
dual exhaust system
intake over exhaust engine
raw exhaust gas
residual exhaust gases
tuned exhaust
tuning the exhaust

Exhaust back pressure:

Any pressure holding back the flow of the gases in an exhaust system. Pressure exerted in exhaust system in reverse direction. Also called back pressure

Exhaust back pressure transducer valve:

(BPV or BPS) a device used to sense exhaust pressure changes and control vacuum to the EGR valve in response to these changes

Exhaust Brake:

An engine device which changes exhaust pressure to assist in slowing down a vehicle. Also called an exhaust retarder

Exhaust cam:

A separate camshaft controlling the opening and closing of the exhaust valves used in twin overhead camshaft engines

Exhaust camshaft:

A separate camshaft controlling the opening and closing of the exhaust valves used in twin overhead camshaft engines

Exhaust chamber:

Part of the two-stroke exhaust system designed to maintain a specified back pressure

Exhaust cutout:

A Y-shaped device that is placed in the exhaust pipe ahead of the muffler. The driver may channel the exhaust through the muffler or out the other leg of the "Y" where the exhaust passes out without going through the muffler.
Also See:
cutout

Exhaust donuts:

The small rubber hangers used to suspend the exhaust system from the chassis pan

Exhaust emission:

See:
exhaust emissions.

Exhaust emission control:

See:
exhaust emission controls

Exhaust emission controls:

Systems or adjustments designed to limit noxious gases in an engine's exhaust. Such controls can be grouped into two broad categories: those designed to reduce or eliminate the formation of harmful pollutants in the engine itself (e.g., retarded spark setting) and those designed to destroy or otherwise alter the pollutants after they have been formed (e.g., air injection, thermal reactors, and catalytic converters). Evaporative emission controls prevent gasoline vapors from escaping into the atmosphere from the fuel tank and carburetor and crankcase controls recycle fumes from the crankcase through the engine.

Exhaust emission control system:

A general term for any system that reduces the harmful exhaust emissions of a motor vehicle, including one or all of the following systems: catalytic converter (with or without oxygen sensor air/fuel control), exhaust gas recirculation, secondary air injection or induction, and positive crankcase ventilation

Exhaust emissions:

The unburned hydrocarbons, carbon monoxide, oxides of nitrogen, and other noxious gases emitted when gasoline is burned in an engine.

Exhaust engine:

See:
intake over exhaust engine

Exhaust gas:

Gas which is the product of the combustion process and which is passed out of the cylinder through the exhaust valve or port into the exhaust system.
Also See:
exhaust gases
raw exhaust gas
residual exhaust gases

Exhaust gas analyzer:

An instrument for determining efficiency with which an engine is burning fuel.
Also See:
exhaust-gas analyzer.

Exhaust-gas analyzer:

An instrument used to measure the exhaust gases (in parts per million, percent, grams per kilometer, or grams per mile) to determine both combustion efficiency and the amount of pollutants in the exhaust.

Exhaust gas check valve:

(EGC) a device that allows air injection system air to enter the exhaust manifold, but prevents a reverse flow in the event of improper operation of other components

Exhaust gas oxygen sensor:

(EGO) a device that changes its output voltage as the exhaust gas oxygen content changes when compared to the oxygen content of the atmosphere. This constantly changing voltage signal is sent to the processor for analysis and adjustment to the air/fuel ratio

Exhaust gas purification system:

An emission control system for diesel engines, which may consist of an exhaust scrubber, a diesel exhaust filter, and/or a catalytic converter

Exhaust gas recirculation:

See:
exhaust-gas recirculation.

Exhaust-gas recirculation:

(EGR) An emission control system where some of the exhaust gases are rerouted from the exhaust manifold into the combustion chamber to make sure that all fuel is burned before entering the atmosphere. The process lowers the combustion temperature and reduces the formation of oxides of nitrogen (NOx) in the exhaust.

Exhaust gas recirculation system:

(EGR) a system used to control oxides of nitrogen (NOx) the exhaust gases are recirculated, lowering the engine combustion temperature, thereby reducing engine pollutants

Exhaust gas recirculation valve:

A valve which admits exhaust to the incoming air/fuel mixture

Exhaust gases:

The burned and unburned gases which are expelled out of the exhaust system after combustion takes place.
Also See:
exhaust emissions

Exhaust header:

Steel tubing connecting pipes between the exhaust ports and the exhaust pipe. Usually a header has been polished to allow for better flow of the exhaust.
Also See:
exhaust manifold

Exhaust heat control valve:

(HCV) a valve which routes hot exhaust gases to the intake manifold heat riser during cold engine operation. Valve can be thermostatically controlled, vacuum operated or computer controlled

Exhaust manifold:

The connecting pipes between the exhaust ports of each cylinder and the exhaust pipe. It is usually made of cast iron. Sometimes called the "exhaust header " but it is usually made of steel tubing.

Exhaust note:

The sound coming from the end of the exhaust pipe. It is usually described as pleasant, loud, throaty, or sporty.

Exhaust oxygen sensor:

Device that detects the amount of oxygen in the exhaust stream and sends that information the ECM. Also called an oxygen sensor or an O2 sensor

Exhaust pipe:

Pipe connecting exhaust manifold or header to the muffler.

Exhaust pollutants:

Exhaust emissions

Exhaust port:

1. The passage in the cylinder head which connects the exhaust valve and the exhaust manifold. The exhaust gases pass through the port to the exhaust manifold or header.
2. On two-stroke engines the exhaust port is cut into the cylinder wall because it does not have valves.
3. That opening which carries the fluid to the downstream pressure of a fluid system.

Also See:
adjustable variable exhaust port
variable exhaust port

Exhaust pressure regulator:

(EPR) a device for increasing exhaust backpressure at specific times to increase exhaust flow to the EGR valve

Exhaust Retarder:

An engine device which changes exhaust pressure to assist in slowing down a vehicle. Also called an exhaust brake

Exhaust scrubber:

A diesel exhaust gas purification system which cools the exhaust and separates nitrogen oxide and oil vapours from the gas stream

Exhaust side:

The side of the engine where the exhaust valves and exhaust manifold are located

Exhaust stroke:

The fourth stroke of a four-stroke cycle where the piston moves upward from bottom dead center to top dead center and pushes the burned exhaust gases out of the cylinder.

Exhaust system:

The pipes, resonators and mufflers that carry the exhaust gases from the exhaust manifold out into the atmosphere.
Also See:
dual exhaust system
stainless-steel exhaust system
twin exhaust system

Exhaust timing:

Exhaust control system developed especially for two-stroke motorcycle engines in order to enhance low and mid-range power

Exhaust treatment:

Any measures taken to reduce the pollutant concentrations in the exhaust of an internal combustion engine released into the atmosphere

Exhaust tuning:

Cutting the exhaust pipe to a length that provides maximum efficiency.

Exhaust turbocharging:

See:
turbocharging

Exhaust valve:

1. The valve through which the burned fuel charge passes on its way from the cylinder to the exhaust manifold. It is driven by the camshaft. When comparing an exhaust valve with an intake valve in the same engine, the part of the exhaust valve that seats into the head (i.e., not the stem) will have a smaller diameter than the intake valve.
2. A movable port which provides an outlet for the cylinder gases in a compressor or engine.

Also See:
sodium-cooled exhaust valve

Exhaust valve closes:

(EVC) A mark on a valve-timing diagram

Exhaust valve opens:

(EVO) A mark on a valve-timing diagram

Exothermal:

Chemical reaction in which heat is released.

Expander:

1. A ring placed under a piston ring to increase ring pressure on the cylinder walls. For instance an oil control ring may have an expander ring to assist the oil-control ring to scrape oil off the cylinder wall and provide further sealing.
   Also See:
   piston ring expander.
2. A device in a drum brake system (either hydraulic or mechanical) which forces the shoes apart into contact with the drum.
3. A disc used in a wheel cylinder which helps to seal the fit between the cup lips and cylinder walls when there is no pressure in the system.

Also See:
bead expander
piston skirt expander
ring expander
skirt expander
tailpipe expander
wedge expander

Expander spacer:

See:
expander ring

Expanding:

See:
piston skirt expanding

Expansion:

An increase in size, for example: when a metal rod is heated, it increases in length and perhaps also in diameter. Expansion is the opposite of contraction.
Also See:
piston expansion
shell expansion

Expansion joint:

Device in piping designed to allow movement of the pipe caused by the pipe's expansion and contraction.

Expansion plug:

A steel plug, slightly dished or cup-shaped. When driven into place it flattens to fit tightly in its seat. In an engine block, expansion plugs (also called freeze plugs or core-hole plugs) are inserted into the holes in the casting through which core was removed when casting was formed. They open into cooling passages and thus provide pressure relief should the engine coolant freeze and expand.
Also See:
core plugs.

Expansion stroke:

See:
power stroke

Expansion tank:

When the engine is heated, the coolant expands to fill any available space (usually in the radiator). Before the introduction of coolant expansion tanks, the excess coolant was forced out of a vent tube and on the ground. The expansion tank collects the coolant so that when the engine cools off, the resultant vacuum sucks the coolant from the tank back into the radiator.

Expansion tube:

A device that converts high pressure liquid refrigerant into low pressure liquid refrigerant (thus lowering its boiling point) before it passes through the evaporator. The expansion valve replaces the thermostatic expansion valve. It is also referred to as a fixed orifice tube

Expansion valve:

A part of an air-conditioning system, located between the condenser and the evaporator that regulates the flow of liquid refrigerant to the vaporator. If cooling needs are low, the valve is almost closed; as additional cooling is required, the valve opens wider so that more liquid refrigerant flows to the evaporator. It reduces the pressure from the high side to the low side and is operated by pressure. Also called an automatic expansion valve (AEV) or "thermostatic expansion valve."

Expansivity:

See:
coefficent of expansion

Expected residual value:

This is the projected or expected value of the vehicle at the end of the lease. Residual value is a measure of the vehicle's expected depreciation.

Expendable refrigerant system:

System which discards the refrigerant after it has evaporated.

Expenditures:

See:
capital expenditures

Experiment:

See:
windsor experiment

Experimental Development Program:

See:
scientific Research and Experimental Development Program

Experimental Safety Vehicle:

(ESV) A special vehicle built for research into and testing of safety features; (compare SID)

Exploded view:

A drawing of a mechanism or structure which shows the parts separately but approximately in the position they occupy when assembled

Explosion:

A rapid disintegration of an object.
Also See:
clutch explosion.

Explosion-proof enclosure:

(EXP-PRF) A special enclosed electrical motor housing designed to withstand an internal explosion of specified gases or vapors and allow the internal flame or explosion to escape, usually used in smaller ratings below 1/3 hp if nonventilated (EPNV) and in fan-cooled (EPFC) in larger ratings

Export Restraint:

See:
Voluntary Export Restraint

Expressway:

A US multilane highway road with limited access to be used for rapid travel with few interchanges.

Ext:

Abbreviation for "exterior."

Extended Cab:

A type of pickup truck (by GM) which has a second row of seating; but unlike a crew cab (which has four full size doors) it has a "half-door" that can be opened only after the main door is opened. The seating is usually a little more cramped than in a crew cab. Also called Club Cab, King Cab, XtraCab, Access Cab, SuperCab, or Cab Plus.

Extension:

A part which is inserted between a ratchet and a socket to provide access to nuts or bolts which are deeply inset or hard to reach. Also called "extension bar" or "extension piece."
Also See:
brake extension
fender extension
load floor extension
park brake extension
piston extension screw
valve extension
wheel arch extension
wing extension

Extension bar:

See:
extension
wobble extension bar

Extension housing:

See:
transmission extension housing

Extension piece:

See:
extension

Extension screw:

See:
piston extension screw

Extension spring:

A closed-coiled helical spring that offers resistance to a pulling force.

Exterior mirror:

The mirror that is usually mounted on the door. In Japan (and other countries) it was mounted on the front fenders. Also called "external mirror."

External combustion engine:

An engine that burns its fuel outside the engine. A steam engine is an external combustion engine.

External diameter:

The outside diameter of a cylinder, tube, or washer

External drive:

Term used to indicate a compressor driven directly from the shaft or by a belt using an external motor. Compressor and motor are serviceable separately.

External drive compressor:

See:
compressor, open type

External equalizer:

Tube connected to low-pressure side of a thermostatic expansion valve diaphragm and to exit end of evaporator.
Also See:
equalizer line

Externally-balanced crankshaft:

A crankshaft that requires external balancing weight, usually on the vibration damper of the flywheel, for balance

External micrometer:

A micrometer for measuring external diameters

External mirror:

The mirror that is usually mounted on the door. In Japan (and other countries) it was mounted on the front fenders. Also called "exterior mirror."

External mix air cap:

A special type of air cap for spray guns. Air and fluid are mixed in the space outside the air cap, directly in front of the nozzle: the most common type of air cap.
Also See:
internal mix air cap

External snap ring:

A split ring held in place by its own tension within the grooves cut around a shaft. Compare internal snap ring.

External thread:

Thread consisting of projecting ridges on the outside of a part such as a bolt or screw (which fits into the corresponding internal thread of a nut). Also called male thread

External vane pump:

A pump with either an elliptic rotating piston or an eccentrically mounted circular rotor

Extinguisher:

See:
fire extinguisher

Extractor:

A device for removing some object (e.g., bearing, bushing, sleeve, bolt, stud, etc.).
Also See:
oil and water extractor
screw extractor
stud extractor

Extras:

Optional items either supplied by the manufacturer at the buyer's request, or added later by the owner. Usually they are things like seat covers, floor mats, additional lights, sunroof, glass tinting, CD changers, etc.

Extreme-pressure lubricant:

(EP lubricant) A lubricant designed and compounded to withstand very heavy loads imposed on gear teeth.

Extruder:

A machine that shapes a rubber compound into a usable form. Uncured rubber is heated to soften and forced through dies having the desired shape and dimensions.

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