The Gearbox

 Most modern gearboxes have five forward gears and one reverse gear!

Functions of the gearbox

1 To match the speed of the engine (revs) to the road speed (Kmh)

2 To allow for the differing power requirements of the vehicle

Use of gears

Lower gears

First gear is the most powerful gear on the car and is used for moving off on the level or on a hill and for very slow speeds.

Second gear is used for moving off on a downhill gradient and for very slow speeds

Intermediate gear

Third gear is used for speeds between 30 and 60 k and is good for building up speed quickly on faster roads.

Higher gears

Fourth gear is used for speeds around 50 k and above. It hasn't got as much speed as third so is not as good as picking up speed quickly.

Fifth gear is the least powerful gear on five speed gearboxes. It is used at higher speeds usually in excess of 60 k. It is a good cruising gear and is most often used on motorways.

Selective gear changing

It is normal practice to go down each gear in turn when slowing down. However in some situations such as changing down gears quickly (eg approaching traffic lights that suddenly change) then a block gear change can be made such as fourth to second or third to first. This is preferable to coasting when the clutch pedal is held down between gear changes.

Engine braking

Engine braking occurs when a lower gear is selected to slow down or prevent the vehicle from picking up speed.

Example 1

When slowing down for a corner second gear is selected which allows the engine to slow down the vehicle as well as the brakes.

Example 2

Approaching a steep down hill gradient second gear is selected which increases the engine revs but prevents the vehicle from picking up speed.

- Manual