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Glossary of terms you will come across during your Phase 2 training.

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Symbol for a warning lampW/l means warning lamp. For instance, charging circuits have a warning lamp fitted to warn the driver if the alternator is not charging. This lamp connects to the alternator at the terminal normally marked w/l, or ind.

Ind means indicator lamp, indicating if the alternator is charging or not.


Typical Walbro carburetorManufacturer of carburetors found on many items of small plant machinery.

From the the Walbro Website:

Walbro Engine Management is the world's largest manufacturer of carburetors and a major manufacturer of ignition systems, fuel injection and air/fuel management components, and fuel storage and delivery components for engines targeted at outdoor power equipment, marine, recreational and two-wheel applications.  Walbro Engine Management has facilities in the United States, Mexico, Italy, Japan, Thailand and China.  Read More...

You can search the Walbro website with their own part numbers, or by other manufacturers' part numbers.


Warrior 2-stroke engineTwo-stroke petrol engine fitted to strimmers.


  • Piston and Barrell kit WR 6574. As of April 2012, €35 from McKennas.
Typical wasted coil coil packThis refers to one type of ignition system in use on modern petrol engines. In a 4 cylinder engine, a system using one coil pack, with 2 coils, each coil producing the spark for two cylinders. Becuase each coil produces a spark for a pair of cylinders (1 and 4; 2 and 3), one cylinder will be compression and the other will be on exhaust. Both will get a spark, so the one going to the cylinder on exhaust is 'wasted', hence the term 'wasted spark' ignition system.
Device in a turbocharged engine that controls the maximum boost pressure that is provided to the inlet manifold.

James Watt

The Watt is the measurement of power, and gets its name from James Watt. This is the modern metric way of measuring power.

The old way of doing it was to measure the power of something relative to the power of a horse:

  • HP: Throughout the United Kingdom, and in many other parts of the world - horsepower
  • CV: In France and other areas of the world under French influence, 'cheval vapeur', or 'steam horse'
  • PS: Often referred to as 'the metric horsepower', this is a German version of measuring power and means 'the strength of a horse'

If a force of 1 Newton moves an object through a distance of 1 metre in 1 second, then 1 Watt of power is said to have been expended.


Waveforms showing the camshaft and crankshaft sensors, primary ignition and fuel injection.Oscilloscopes measure voltages, and plot these values against time. The voltage is on the vertical axis and the time is along the horizontal axis. The resulting graph is known as a waveform.

In automotive diagnostics, capturing and analysing these waveforms can be very useful in diagnosing faults. The waveform show is from a Ford Fiesta engine at idle (click image for a larger view). The waveforms are, from the top:

A vertical force exerted by a mass as a result of gravity.

In science and engineering, the weight of an object is related to the force acting on the object due to gravity.

Weight can be defined as the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.

Gravity can be defined as the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.

Anything that has mass attracts everything in the universe toward itself.

Earth bound bodies (objects) have limited mass, so it is difficult to measure this infinitesimally small force.

The earth itself, however, is massive and we can measure this force of attraction, which we call 'weight'. 

Because gravity is a force, this force will cause movement. In our experience on the surface of the earth, we experience this as a force pulling us toward the centre of the earth.

If we were to allow ourselves to be pulled toward the centre of the earth in an unrestricted way, say, by jumping from an aircraft, we would immediately begin to accelerate toward the centre of the earth.


An electrical device devised by Charles Wheatstone in 1843, and used for finding the value of an unknown resistor.

A Wheatstone Bridge

Check out Page 34 of Hillier's Fundamentals of Automotive Electronics for more information.

Charles Wheatstone

More on Charles Wheatstone.

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