Automatic transmissions used to only be an option in certain luxury vehicles. Today most vehicles come standard with it in all price ranges. An automatic transmission is a transmission that shifts gears accordingly without the driver having to do anything.
An automatic transmission comes with pre-selected gear ranges. Some vehicles use what is called the CVT (continuous variable transmission). The CVT can change ratios over versus the set gear ratios.
Standard transmissions compared to the automatic transmission have certain differences. A standard transmission has an extra pedal that is called the clutch, and needs to be manually pushed down by the foot of the driver each and every time the transmission is shifted between gears. With an automatic transmission there are no extra pedals needed because the engine shifts on its own without a needed prompting from the driver.
There is no gearshift in an automatic transmission. All the driver needs to do is put the car in drive, and the engine does the rest of the work.
There are standard sets of gears that come with an automatic transmission vehicle. The driver has to move the shifter in motion to any of the below:
Park-P this will lock up the transmission, and keep it at a standstill until it is disengaged.
Reverse-R this gear gives the vehicle the ability to move backwards. The automobile must be at a standstill before you engage this gear.
Neutral-N in this position the vehicle is technically not in any gear. In this mode the transmission is disconnected.
Drive-D when put into this gear, it allows the vehicle to move forward and to increase speed.
Overdrive- the vehicle is only using minimal transmission in this gear. Typically the only time the vehicle is in overdrive is when going at a steady speed of around 40 mph (miles per hour)