Gearboxes are designed to convert the power from an engine into the mechanical movement of the drive shaft, powering anything from wheels on an automobile to the rotors of a helicopter. As the engine provides more power, larger gears are selected within the gearbox, increasing the final speed of the drive shaft. If you are purchasing a new vehicle, you need to know what the advantages and disadvantages of manual and automatic gearboxes are.
Cars with automatic transmission are easier to drive than those fitted with manual gearboxes. Drivers do not have to learn how, when or why they should change gear. In city driving, the constant gear shifting required with a manual vehicle can become physically tiring.
Vehicles fitted with manual gearboxes can be easier to control in certain situations. When approaching a corner or a steep incline, a driver can change down to a lower gear providing "engine braking." This is where the revolutions the engine can make are restricted by the gear selection. Changing to a higher gear when pulling away on an icy road can also prevent the wheels from spinning. An advantage of an automatic transmission however, is that you cannot stall the engine when pulling away as the correct gearing will always be selected.
In the past, automatic transmissions where less fuel efficient than their manual counterparts. Modern automatic gearboxes have improved and, in some cases, beat manual variants in fuel efficiency.
If your battery runs out of charge, it will not have enough power to start your engine. With a manual transmission vehicle you can start the vehicle by "bump starting." With the ignition on, first gear is selected and the driver keeps the clutch pedal depressed. A helper pushes the car forwards and, if a high enough speed is reached, the driver can release the clutch. The car starts as the gearbox spins the flywheel and pushes the pistons up and down while the alternator belt provides enough current for the spark plugs to ignite the fuel. This method cannot be used to start a vehicle fitted with automatic transmission.
