THE IMAGES SHOWN HERE DEPICTS GEAR TEETH COMBINATION DURING EACH SHIFT (SEE THE COLORED TEETH )
Manual Transmission : The manual transmission provides a means of varying the relationship between the speed of the engine and the speed of the wheels. Varying these gear ratios allows the right amount of engine power at many different speeds. Manual transmissions require use of a clutch to apply and remove engine torque to the transmission input shaft. The clutch allows this to happen gradually that so that the car can be started from a complete stop. Modern manual transmissions do not disengage any of the forward drive gears, they are simply connected to their shafts through the use of synchronizers. Reverse is achieved through reverse idler gears, which are engaged to move the car backwards. Some manual transmissions have an overdrive. An overdrive is a mechanical unit bolted to the rear of the transmission. It is usually known as fifth gear. When you use it, it will reduce the engine speed by about one-third, while maintaining the same road speed. Chrysler came out with the first overdrive transmission in 1934.
Automatic Transmissions :
An automatic transmission is much easier to drive than a manual transmission, because you don't have to use a clutch pedal or gearshift lever. An automatic transmission does the work all by itself. The first automatic transmission appeared in 1939. Automatic transmissions automatically change to higher and lower gears with changes in the car's speed and the load on the engine. These transmissions are also aware of how far down you have pushed the gas pedal, and shift accordingly. The system is operated by transmission fluid pressure; shift valves control the gear changes. A 'governor' controls the shifting
of the gears. It's linked to the output shaft and throttle valve and controls the transmission fluid supply, at different pressures, to the shift valve. Here's how it works: the output shaft turns the governor. The faster the car goes, the faster the governor turns. Oil is sent from the pump to the shift valves by centrifugal force from the governor. The shift valves move out, and send the transmission fluid to the gear shifting mechanisms in the transmission. When you slow down, the valves move in, and send the transmission fluid in the opposite direction. This action changes the gears. By routing the pressure to the clutches and brake bands, the different gears are selected.
HAPPY DRIVING !!!
