E – Terminologies

ECCENTRIC AND STRAP – An eccentric is a disc having its axis of rotation out of its centre. It is equivalent to a crankpin which is so large in diameter that embraces the shaft to which it is attached and dispenses with arms. Converts rotary motion into reciprocating motion.

EFFICIENCY – Ratio of the useful work performed by a prime mover to the energy expended, that is, the output divided by the input.

ENBLOCK CYLINDERS – Two or more cylinders cast integral, that is all in one casting.

ELLIOT TYPE AXLE – Solid bar front axle on which ends span or straddle steering knuckle.

EMERGENCY BRAKE – is the hand brake, operated by a lever, is used when the vehicle is left parked and prevents the vehicle from moving. The hand brake can be applied to stop the vehicle when the service brake fails.

EPICYCLIC GEAR – In the epicyclic gearing, at least one gear not only rotates about its own axis, but also rotates about some other axis.

EQUALIZER LINK – A common connector in the parking brake system that causes both rear brakes to be applied with the same cable tension.

EVASIVE MANEUVER – Rapid steering changes to avoid obstacles in the path of the vehicle.

EXPANSION TANK – A tank at the top of an automobile radiator which provides room for heated coolant to expand and give off any air that may be trapped in the coolant. Also used in some fuel tanks to prevent fuel from spilling from the tank because of expansion.

EFFECTIVE STROKE OF PLUNGER – The distance from the point of closure of the ports by the plunger top to the point of opening of the spill port by the helical groove on the surface of the plunger. This decides duration and quantity of fuel delivery by the pump.

ENGINE DERATING – Reducing maximum fuel flow to the engine.

EROSION SCAB – Casting defect occurring where the metal has been agitated, boiled, or has partially eroded away the sand, leaving a solid mass of sand and metal at that particular spot.

EXPENDABLE PATTERN – In investment moulding, the wax or plastic pattern that is left in the mould and later melted and burned out.

EXPANSION SCABS – Rough thin layers of metal partially separated from the body of the casting by a thin layer of sand and held in place by a thin vein of metal.

EXTERNAL CHILLS – Various materials of high heat capacity such as

metals, graphite etc. forming parts of walls of the mould cavity to

promote rapid heat extraction from molten metal.

EXTERNAL PRESSURE CASTINGS – In this process, highly fluid metal is forced under considerable external pressure into metal moulds, the pressure being maintained until solidification is complete.

ELASTOMER – Any of various elastic substances resembling rubber.

ELECTRIC STEEL – Special alloy steel, tool steel, and steel for castings, melted in electric furnaces that permit very close control and the addition of alloying elements directly into the furnaces.

ELECTRICAL INSULATING MATERIALS – The materials which offer a very large resistance to flow of current, and for that reason they are used to keep the current in its proper path along the conductor.

ELECTRICAL SHEETS – It is the trade name for iron and a steel sheet used in the manufacture of punching for laminated magnetic circuits and usually refers to silicon steel sheets.

ELECTROLYTE – A non-metallic conductor, usually a fluid, in which electric current is carried by the movement of ions.

ELECTROMAGNET – A magnet of variable strength produced by passing current through conductors around a soft iron core.

ELEKTRON – Magnesium base alloy supplied in the form of tubes, sheets, extruded sections, forgings and castings.

ELEMENT – A substance which cannot be chemically broken down to simpler substances.

EMERY – An abrasive material which, like corundum or aluminium oxide type, is a natural abrasive.

EMULSIFIER – (1) A material that increases the stability of dispersion of one liquid in another. (2) In penetrant inspection, a material that is added to some penetrant after the penetrant is applied to make a water washable mixture.

ENAMEL – Type of paint that dries to a smooth, glossy finish.

ERITH SAND – Yellow, close grained, refractory moulding sand, having good strength and reasonable permeability.

EUTECTIC – Mixture (an alloy) in which the proportions of the constituents are such that the mixture has a lower melting point than any of the constituents.

ECOSPHERE – The layer of earth and troposphere inhabited by or suitable for existence of living organisms.

EFFLUENT – Waste material discharged into the environment, treated or untreated.

EGR SYSTEM – Exhaust gas recirculation system. It sends part of the exhaust gas back through the engine by way of the carburettor or intake manifold, which reduces the amount of NOthat is formed by an engine.

ELECTOSTATIC PRECIPITATOR – An air pollution control device in which solid or liquid particulates in a gas stream are charged as they pass through an electric field and precipitated on a collection surface.

ELUTRIATION – A process of separating lighter particles from heavier particles by washing solid waste with a slowly moving upward stream of fluid that carried the lighter particles with it.

EMISSION CONTROLS – A term applied to any device or modification added onto, or designed into a motor vehicle for the purpose of controlling a source of air pollution emission.

ETHANOL – Ethyl alcohol produced by east fermentation of a variety of carbohydrates such as saccharin (sugar canes, sugar beets, molasses and fruit juices), starch (cereals and potatoes) or cellulose (wood waste, sulphite liquor).

ETHYL GASOLINE – Gasoline to which ethyl fluid has been added to improve its resistance to knocking. Slows down burning rate and thereby creates a smooth pressure curve that will allow the gasoline to be used in high compression engines.

EVAPORATIVE EMISSION CONTROL SYSTEM – A system which prevents the escape of gasoline vapours from the fuel tank or carburettor float bowl to the atmosphere while the engine is off.

The vapours are stored in a canister, or in the crankcase until the engine is started.

EXCESS AIR – Air present in the cylinder over and above that which is theoretically necessary to burn the fuel.

EXHAUST GAS – The products of combustion coming out from an internal combustion engine.

EXHAUST GAS ANALYZER – A device for sampling the exhaust gas from an engine to determine the amounts of pollutants in the exhaust gas. This determines combustion efficiency.

EFFICIENCY OF IMPULSE BLADING – Ratio of the delivered power or energy, to the power or energy supplied in kinetic form to an impulse blade.

ERICSON CYCLE – The gas turbine cycle which incorporates multistage compression with intercooling, and multistage expansion with reheating.

ELECTROLYTIC POLISHING – Method of polishing metals in which the work forms the anode of an electrical circuit, and is suspended in a suitable bath of acid.

ELECTROPLATING – Deposition of a metal on a surface by electrolytic action.

ELEMENT FILTER – A disposable oil or air filter that uses gauze or paper as filtering material.

ENBLOCK – One piece, such as an engine cylinder block cast in one piece.

ENGINE – A machine that converts heat energy into mechanical energy (mechanical action in a car). The assembly that burns fuel to produce power, sometimes referred to as the power plant.

ENGINE DISPLACEMENT – Volume of space through which head of piston moves in full length of its stroke multiplied by the number of cylinders in the engine. Result is given in cubic centimetres.

ENGINE TUNE UP – The procedure for checking and adjusting the various engine components so that the engine is restored to top operating condition.

ETHYLENE GLYCOL – A chemical compound (solution) added to the engine coolant to reduce its freezing point and thereby protect the cooling system against freezing of the coolant.

EXHAUST CUTOUT – Y shaped device placed in the exhaust pipe of an engine ahead of muffler. Driver may channel exhaust through the muffler or into the other leg of the Y where the exhaust gases pass out without going through the muffler.

EXHAUST MANIFOLD – A housing with a series of connecting pipes between the exhaust ports and the exhaust pipe through which hot burned gases from the engine cylinders flow.

EXHAUST PIPE – Pipe connecting exhaust manifold to the muffler.

EXHAUST PORT – The opening through which exhaust gases pass from the cylinders to the manifold.

EXHAUST STROKE – The piston stroke from BDC to TDC during which the exhaust valve is open so that the burned gases are forced out from the cylinder.

EXHAUST SYSTEM – A group of parts consisting of the exhaust manifold, exhaust pipe, muffler, tailpipe and resonator if used.

EXHAUST TUNING – Cutting exhaust pipe to such length that provides maximum efficiency.

EXHAUST VALVE – The valve which opens to allow burned gases to exhaust from the engine cylinder into the exhaust manifold during the exhaust stroke.

EXPANSION PLUG – A plug that is slightly dished out and used to seal core passages in the cylinder block and cylinder head. When driven into place, it is flattened and expanded to fit tightly.

EXPANSION RATIO – Ratio of the total volume when the piston is at BDC to the clearance volume when the piston is at TDC (normally equal to compression ratio).

EVAPORATIVE COOLING SYSTEM – A cooling system in which the heat finally passes to atmosphere by evaporation of the coolant. This system may be either open or closed.

ENGINEERS TAPERS – are intended for measuring hole sizes, slot widths, caliper settings and so on.

EXPANDING MANDREL – It is used to hold work on an internal diameter. It is similar in principle to a spring cullet. Three jaws are arranged to expand outward and clamp the work, as a tapered pin is forced inward.

ELECTRIC DRILL – Hand operated, portable drilling machine driven by electric power.

ENGINE – A machine that converts heat energy into mechanical energy. The assembly that burns fuel to produce power is sometimes called POWER PLANT.

ECCENTRIC – A circle or cylinder having a different center from another coinciding circle or cylinder. Also, a device for converting rotary motion to reciprocating motion.

END PLAY – As applied to a shaft, the amount that the shaft can move backward and forward.

EYE BOLT – A bolt threaded at one end and bent to a loop at the other end.

ELECTRIC DRIVE – An arrangement consisting of an electric motor, suitable motor controls, and a gear train linking the motor with the operating mechanism.

ELEVATOR – A platform or caged hoist that moves material or personnel from one level to another.

ELEVATING GRADER – Machine that cuts soil layer by layer and moves it away by means of a conveyor into a dump or onto transporting facilities.

ESCALATOR – Chain conveyor specially adapted for the vertical transportation of people over an inclined path. It is an inclined conveyor with the driving traction in the form of steeps attached to step drive chains and each escalator step is carried on four wheels riding on tracks.

EXCELSIOR – Shredded or curled pieces of wood.

ELASTIC DEFORMATION – The movement or deflection of a material when an external load is applied that is less than the elastic limit.

ELASTICITY – The ability of a material to return to its original form after the load has been removed.

ELASTIC LIMIT – Maximum stress that can be applied to a metal without causing plastic deformation that will remain after the load is relaxed to zero.

ELASTIC RATIO – It is the ratio of yield point stress to tensile strength of a metal.

ELECTROLYSIS – Chemical change resulting from the passage of an electric current through an electrolyte.

ELONGATION – Elongation is the strain produced by uniaxial tension.

EMBRITTLEMENT – Reduction in the normal ductility of a metal due to a physical or chemical change.

ENDURANCE LIMIT – The limiting stress below which the metal will withstand without fracture an infinitely large number of cycles of stress.

ENDURANCE RATIO – It is the ratio between the endurance limit to tensile strength.

EUTECTIC – The alloy which has the lowest melting point possible for a given composition.

EUTECTOID – A solid solution of any series which cools without change to its temperature of final composition.

EDGING – Edging is a gathering operation. Here the metal is displaced to the desired shape by striking it between two dies. As the dies strike, the stock, metal is gathered toward the center of the cavity and some sideways movement also takes place.

ELECTRON BEAM WELDING – The fusion of material by energy imparted from an intense beam of electrons.

ELECTROPLATING – Coating an object with a thin layer of metal through electrolytic deposition.

ELECTRIC RESISTANCE WELDING – Uniting the parts by heating them to welding temperatures and then forcing the ends together by mechanical pressure.

EMBOSSING – Operation of raising a design or form above the surface of a component by means of high pressure affected by pressing or squeezing action.

ETCHING – Process of marking a metal by eating into it with an acid or other chemical.

EXFOLIATION – Cracking of the outer skin of the metal.

EXTRUSION – Process in which metal (often heated) is caused to flow through a restricted orifice by using an extremely high force, so creating an extremely elongated strip of uniform, but comparatively small cross-section.

ELLIPTIC TRAMMEL – An instrument used for drawing ellipses.

ENERGY – Capacity for doing work.

EPICYCLIC GEAR TRAINS – Gear trains in which the axis of one or more gears moves relative to the frame. The gear at the centre is called the SUN, and gears whose axes move are called PLANETS. Also called PLANETARY GEARS.

EPICYCLOID – The locus of a point on the circumference of a circle which rolls outside a circular arc, without slipping.

EBULLATOR – A device inserted in flooded evaporator tubes to prevent evaporator from being oil bound.

EJECTOR – A device which utilizes static pressure to build up a high fluid velocity in a restricted area to obtain a lower static pressure at that point so that fluid from another source may be drawn in.

ELECTROMAGNETIC CLUTCH MECHANISM – Device which when engaged, turns the compressor shaft to start piston movement.

ELECTROPNEUMATIC AIR CONDITIONING SYSTEM – A system, in which an adjustable sensing device permits the selection of comfortable conditions, has two thermistor to monitor and sense both the outside air and the air in the passenger compartment.

ELIMINATOR PLATES – Protect refrigerated spaces and air from brine spray.

EMULSIFICATION – Formation of an emulsion, i.e., a mixture of small droplets of two or more liquids which do not dissolve with each other.

EQUALIZERS – Connections used with thermostatic expansion valves when the superheat setting of the expansion valve cannot control the amount of refrigerant which flows through the coil.

EQUILIBRIUM – Condition existing at saturation, the molecules of the refrigerant in liquid state are changing into the vapour state as rapidly as vapour molecules are changing into the liquid state.

EUTECTIC POINT – The lowest freezing point (temperature obtainable) when the concentration of solid in a solution is increased gradually.

EUTECTIC SOLUTION – A solution which can be made so that it freezes and melts at a specific temperature.

EVACUATE – To discharge refrigerant from the air conditioning system into the atmosphere or a holding tank, and then to vacuum pump the system in order to boil away any moisture.

EVAPORATOR – Device in the low pressure side of a refrigeration system through which the unwanted heat flows; absorbs the heat in the system in order that it may be moved or transferred to the condenser.

EVAPORATOR (automotive ac system) – Device that cools, dehumidifies, and takes the pollen and dust from the air before it enters the passenger compartment.

EVAPORATOR DUTY – The amount of heat which can be removed by the evaporator i.e., the amount of refrigeration accomplished.


SYSTEM – Uses either a suction throttling valve, a pilot operated absolute valve, or an evaporator pressure regulator valve to control evaporator temperature.

EVAPORATOR REGULATOR VALVES – Provide independent temperature control for each evaporator.

EXPANSION VALVE – Metering device which provides a restriction so that there is a steady flow of refrigerant and also maintains the difference of pressure required to change the state of the refrigerant.

ECONOMIZER VALVE – Fuel flow control device within the carburettor.

ELECTRIC ASSIST CHOKE – A choke which uses a small electric heating element to warm the choke spring, causing it to release more quickly. This reduces exhaust emissions during the start up of a cold engine.

ELECTRODE (spark plug) – Centre electrode rod passing through the insulator forms one electrode. The rod welded to the shell forms another. They are referred as centre and side electrodes.

ELECTRONIC FUEL INJECTION – A fuel injection system used for injecting gasoline into the spark ignition engines, which has an electronic control system to time and meter the fuel injected.

ELECTRONIC IGNITION SYSTEM – An ignition system using transistors, which does not have mechanical contact breaker points in the distributor, but uses the distributor for distributing the secondary voltage to the spark plugs.

ERODED PISTON (crown) – A condition caused by detonation or pre-ignition where the gas temperatures are raised so high that part of piston crown is heated and melted away.

ESC – Electronic spark control.

ENERGY TRANSFER MAGNETO – A self powered ignition system that consists of a flywheel with permanent magnets that rotate around a laminated core with coil windings, an induction coil, contact points and capacitor.

ECONOMIZER – Feed water heater placed between the boiler and chimney (exhaust) stack, so as to absorb a portion of the heat in the gases, not absorbed by the boiler.

ELECTRIC BOILER – Unit in which the resistance of water between solid metal electrodes generates heat and thereby produces steam.

EROSION – It is a mechanical action causing wear by abrasion.

EXTERNALLY FIRED BOILER – One in which the furnace is outside the boiler shell, the furnace walls being usually of fire brick. Example, the familiar horizontal return tubular boiler.

ECCENTRICITY – The distance between the centre of the crankshaft and the centre of the eccentric and is equal to the effective crank arm of the eccentric.

ENGINE RELATIVE EFFICIENCY – Ratio of actual thermal efficiency to that of the Rankine cycle for the same pressure and temperature conditions.

EVAPORATIVE CONDENSER – A type of surface condenser in which the steam is fed through the condenser tubes over which cooling water is sprayed and cooling is affected mainly by evaporation of the sprayed water.

EXHAUST LAP – The overlap of the release edge of the D slide valve over the release edge of the port when the valve is in the mid position which is the middle of its travel.

EFFICIENCY – Ratio of the useful work performed by a prime mover to the energy expended. In other words the output divided by the input.

ENERGY – Stored work, that is the ability to do work.

ENTHALPY – Name given to the total heat in the fluid at any temperature.

ENTROPY TEMPERATURE DIAGRAM – In thermodynamics, the base of a heat diagram, the area of which is heat units and the altitude of which is absolute temperature.

EQUIVALENT EVAPORATION – Amount of water in kg. that would be evaporated from water at 100°C into steam at 100°C and 1.03 kscm, by the heat put into steam actually evaporated in one hour by 1 kg of fuel.

EVAPORATION – Process by which a liquid changes into a vapour as a result of absorbing heat.

EVAPORATIVE CONDENSER – Combines the principles of forced circulation convection currents with the ability of a vaporizing liquid to absorb heat.

EXTERNAL LATENT HEAT – When vaporization takes place, the amount of heat required because of the work in pushing back the atmosphere to make room for the steam.

EXTRINSIC PROPERTIES – Also called extensive properties, are those properties which are dependent on the mass of the system. Examples are volume, weight and total energy.

ELLIPTICAL PORT SHAPE – Rounded port shape designed to prevent ring catching in large ports of two stroke cycle engines.

ENDLESS CHAIN – A roller chain without a master link for connection of ends. All pin links are permanently riveted.

EXHAUST PORT – In a two stroke engine, the passage way located in the upper portion of the cylinder opposite from the intake port, that channels spent combustion gases to the exhaust system.

EXHAUST PORT TIMING – Amount of time, two stroke cycle exhaust port is open, expressed in crankshaft degrees or piston travel.

EXTENSION – The return or stretching outward of suspension components (after compression) caused by spring pressure.

EDGE JOINT – A joint between the edges of two or more parallel or nearly parallel members.

ELECTROGAS WELDING – Arc welding in which coalescence is affected by heating the metals with an arc produced between a continuous filler metal electrode and the work. Shielding is by inert gas.

ELECTRO SLAG WELDING – A welding process producing coalescence of metals with molten slag that melts the filler metal and the surfaces of the work-pieces. The weld pool is shielded by slag.

EMISSIVE ELECTRODE – A filler metal electrode consisting of a core of a bare electrode or a composite electrode to which a very light coating has been applied to produce a stable arc.

EXPLOSION WELDING – A solid state welding process in which coalescence is affected by high velocity movement of the work-pieces, produced by a controlled detonation.

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