These are relatively simple devices, the engine rotates and torque is produced by a turning effort (load), the clutch or fluid flywheel transfers this energy into the gearbox which then through gearing increases the effort provided, in other words, the input torque is multipled by the gearing to the output shaft which makes a car accelerate
metals and rubber
In such a gearbox it simply means 'Drive'. Automatic gearboxes are less efficient, fuel wise, than manual gearboxes. They were introduced as a measure for people with less mechanical knowledge and skill to be able to 'drive'.
Gearboxes get hot because of the long usage. It can be hot may be because of the oil used in it.
series 3 gearboxes have synchromesh on 1st and 2nd Addendum: Synchromesh meaning you don't have to double-clutch them like the earlier gearboxes. they are also a stronger transmission.
There are several types of gearboxes and each is specialized for certain applications. Some of the configurations are helical, bevel, spur, worm, and planetary.
if it is spring no electric yes
Sure most new or near new (Especially in the last 15 years) cars that have manual gearboxes are front wheel drive.
In automatic gearboxes these solenoids change gears for you. It helps the car to down-shift, while at the same time keeping the desired level of torque as well as speed.
Automatic and Manual gearboxes are essentially the same, except that the driver does the shifting for a manual gearbox(my personal preference), and a computer shifts for an automatic gearbox.
No
The difference between the diameter of the gears.
On the gearbox :) common for all gearboxes is a filling hole aprox halfway up, in front or on the outside. Google for images of gearboxes , helps a lot.