G or g Unit of force equivalent to the force of the Earth's gravity.

G-force A force on an object equivalent to the force applied by the Earth's gravity.

G/C Clamp A clamp (hand tool) shaped like a G/C.

Gaiter A rubber (or similar) boot used to cover working components. It is used to keep dirt out and in some cases lubrication in place. Also slang for alligator...

gal Gallon

Galleries See Main Gallery.

Galvanize A protective process for steel sheet where a thin surface layer of zinc is applied by hot dipping the steel into a bath of molten zinc.

Ganged Switch An electrical switch that operates two or more circuits from one switching point.

Gas A fluid state of matter when the atoms are free. The least dense state of matter which can have three states, solid, liquid and gas.

Gas Analyser Electronic equipment that measures exhaust gas constituents.

Gas Analyzer See Gas Analyser.

Gas Turbine A type of internal combustion that uses rotating blades in a compressor to provide charging of the combustion chamber. The output gas pressure is used to drive turbine blades which are connected by a shaft to drive the compressor and a transmission gearbox or in the case of aircraft jet engines to provide air propulsion.

Gasket A material that is fitted between faces to take up the irregularity of the surface finishes and provide a gas or liquid seal.

Gasoline A hydrocarbon fuel made up from carbon and hydrogen elements. Used as a fuel for internal combustion engines. Also petrol.

Gassing The formation, in the can, of gaseous products in a coating material, due to the reaction between two or more constituents of the coating material or between the latter and the metal of the container. Characterised by a 'Pop' sound when opening paint containers

Gate In transmission systems a device to guide a gear into any one position at any one time. In electronics a logic device for regulating electrical current flow according to input voltage levels.

GCM Governor Control Module.

GDi Gasoline direct injection. Petrol/Gasoline is injected directly into the combustion chamber under high pressure.

Gear A method of providing leverage. Toothed wheel that meshes with another toothed wheel.

Gear Brake Part of an automatic gearbox, the brake is often a band of friction material.

Gear Cluster A series of fixed gears on one shaft. Used to provide gear selection by engagement with freely rotating gears on another shaft. The selection is made by locking the freely rotating gear to the shaft. This can be by the use of a sliding hub or a sliding gear splined to the output shaft.

Gear Clutch A clutch that connects or disconnects drive to a gear.

Gear Cogs Toothed wheels that mesh with other toothed wheels.

Gear Lash The clearance between the teeth of two meshing gears. Also known as backlash when applied to gears.

Gear Pump An oil pump using two meshed gears to provide a positive pumping action. The teeth are of the two gears run in mesh. Where they come out of mesh a small chamber forms to allow oil to flow in, the oil is carried round the periphery of pump in the gear teeth and when the teeth come into mesh the chamber is reduced in size and the oil forced from the pump.

Gear Ratio Ratio of angular velocities of pairs of meshing gears. Number of teeth on driven gear divided by number of teeth on driver gear.

Gear Reduction A gear drive that reduces the rotational speed of the output shaft below that of the input shaft.

Gear Train Two or more gears in mesh that transmit a drive through them.

Gearbox A housing containing gears to allow different ratios to be selected.

Geared Distributor A distributor driven by a gear from the engine.

Gearshift The mechanism for selecting gears in the transmission. Consists of the driver's gear lever, the linkage to the transmission gearbox, and the selectors in the gearbox.

GEM Governor Electronic Module.

GEN Generator.

Generator Machine for converting mechanical energy into electrical energy.

Generic A common type or something that is used for a variety of tasks.

Gerotor Pump A type of positive displacement oil pump that uses two gears on eccentric axes. One gear is on a shaft inside another rotating in the housing. The pumping and carrying chambers are formed between the gear teeth.

Glare Reflection from the sun or a light onto the computer screen making it difficult to see properly.

Glaze A polish that is safe for use on fresh paints. Some glazes contain a mild abrasive that will remove minor surface imperfections. When a glaze with an abrasive is used, it should be followed by application of wax on cured paint or a hand glaze on fresh paint. A glaze also does not contain silicone.

Glazier Person who works with glass.

Gloss The ability of a surface to reflect light. Measured by determining the percentage of light reflected from a surface at certain angles.

Gloss Meter An apparatus for measuring the gloss of paint film.

Glow Plug Cold start device for diesel engine. Fitted into the combustion chamber and heated by an electrical current so that the injected air and fuel is heated as an aid to ignition when the engine is cold.

GND Ground.

Google Popular Search Engine.

Governor A control device that limits the speed of a unit or controls or senses the operation of a unit. An example is the governor in a diesel injection pump which controls the engine speed.

Governor Pressure The control pressure in an automatic transmission that senses vehicle speed. It is applied to the hydraulic control unit or valve body to effect gear shifts in relation to vehicle speed.

Governor Valve The valve in an automatic transmission, which is fitted on the output shaft. The rotational speed acts on a spring-loaded valve to regulate pump pressure. The governor pressure acts on the gear shift control plunger in the valve body.

GPM Grams Per Mile

GPS Global Positioning System: This is a navigational system involving satellites and computers that can determine the latitude and longitude of a receiver on Earth by computing the time difference for signals from different satellites to reach the receiver.

Grab (Brake) A braking condition where the brakes lock up when light pedal effort is applied. Caused by brake linings digging into the drum or disc on application. Usually cured by forming a chamfer on the leading edge of the lining.

Grammar Forming well written, easy to read sentences, paragraphs and documents with the use of punctuation (i.e., full stops, commas etc.).

Gravelometer A device that propels rocks at a painted substrate to measure the resistance the finish has to rock chips.

Gravity The attraction that all masses experience as a force towards the earth - or any other planet for that matter!

Gravity-feed Gun A spray gun which has the paint container on the top of the gun, allowing the paint to flow into the fluid passage by gravity.

Grease A thick sticky lubricant made from a variety of bases, usually derived from crude oils, and used for bearing and chassis lubrication.

Greenhouse gases Gases that are a natural part of the atmosphere. They absorb and re-radiate the sun's warmth, and maintain the Earth's surface temperature at a level necessary to support life.

Grinding Abrading painted or unpainted metal surfaces to remove paint/corrosion or prepare the area for filling.

Grit Refers to the abrasive size used in flatting papers, discs, etc. and is classified using 'P' grades, e.g. P40, P120, P600 and so on. The larger the number, the finer the abrasive

Gritty A paint product is said to be gritty when it contains large particles, from insufficient dispersion during mixing or when it contains large hard particles of foreign materials.

Grommet A blind grommet is a rubber insert fitted into a hole in a plate to blank off the plate. Other types are used to provide protection for cables or pipes that pass through a hole.

Groove (Tire) A channel cut in the tread of a tire to facilitate the dispersal of road surface water.

Groove (Tyre) (1) A channel cut in the tread of a tyre to facilitate the dispersal of road surface water. (2) The machined slot around the piston into which the rings are fitted.

Ground (Earth) The electrical termination for components connected into a vehicle direct current ground return circuit. On mains electricity a safety route for an electrical short circuit used as a means of protecting people or electrical components from electrical overload.

Ground (Earth) Cable The battery cable connecting the return side of a vehicle circuit to a terminal on the battery where a ground return circuit is used.

Ground Clearance The dimension under a vehicle which clears any obstacles in the roadway.

Ground Test A test to make sure the earth or ground or chassis electrical connection is in good working order.

Grounding A safety practice where two objects are interconnected with clamps and bare wire. This equalizes the electrical potential between the objects and helps prevent static sparks that could ignite flammable materials.

Gudgeon Pin The piston pin that connects a piston to a connecting rod. Fitted at the little end of the connecting rod. Also wrist pin.

Gum Petroleum distillate formed during combustion particularly with poor fuel quality. The gum is deposited on cylinder walls and increases the tendency for glazing.

Gun Body The main part of the spray gun to which all other component parts are attached.

GVW Gross Vehicle Weight