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The distributor is an electo-mechanical device which takes high-voltage electrical energy from the ignition coil and delivers it to the spark plugs in the correct order.
Most cars have one distributor, but engines with twin-plug ignition like Alfa Romeo's Twin Spark units and the 1960s Aston Martin DB4GT have two distributors.
Modern cars have solid-state ignition systems without a distributor, improving reliability and reducing maintenance.
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Drag is a term used in aerodynamics for the wind resistance of an object.
Aerodynamic drag is affected by:
- the shape of the object, measured by its coefficient of drag (Cd)
- the frontal area of the object
- the speed at which the object is moving relative to the air around it
- the density of the air through which it is moving
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In the UK driveshaft means the shaft from the differential to the wheel hub – sometimes called a halfshaft.
In the US driveshaft means the shaft from the gearbox to the final drive unit – sometimes called a propellor shaft or Cardan shaft.
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A dry sump lubrication system has no reservoir of oil under the engine. Instead, oil which drains down to the bottom of the engine is pumped to a remote reservoir using a scavenge pump. Oil is then delivered from the reservoir to the engine using a pressure pump.
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The differential is a gear system within the final drive which allows the driving wheels to turn at different speeds in a corner.
The inner wheel is closer to the apex of a corner, with a smaller radius of turn, so it travels a shorter distance than the outer wheel. A differential is needed to ensure that both wheels can drive the car while still being able to travel different distances in the corner.
A normal or 'open differential' allows one wheel to be stationary while the other continues to rotate. An open differential can cause a loss of grip in some circumstances.
See also limited slip differential, locked differential
