How Automatic Transmission Works?

Automatic Transmission

The automatic transmission looks relatively straightforward; after all, just put it in Drive and go. But like most things in the auto industry, there is a lot of complexity involved in making it more comfortable.


The engine has a heavy centre cylinder rotating crankshaft that provides rotational power to the wheels. “Engine speed” is the speed of the crankshaft, measured in revolutions per minute or “revolutions per minute”.

Most engines generate most of their power over a relatively narrow speed range, but a more comprehensive range is needed to drive a vehicle.

The transmission is a vital link, increasing torque to speed up stopping or preventing the engine from rolling excessively on the highway.

The automatic transmission uses sensors to determine when to change gears and changes them using internal oil pressure.

While several components are built into the drivetrain and its actual operation is a bit more complicated than the simplified version shown here, the key elements are the torque converter and planetary gears.

According to Meineke, most cars use a form of automatic transmission called hydraulic planetary automatic transmission, which is also used in a larger version in some industrial and commercial equipment and heavy vehicles.

A fluid clutch has replaced the friction clutches, and the system sets a set of speed ranges according to the needs of the car. When you park the vehicle, all gears are locked to prevent the car from rolling forward or backwards.

A less common option is an Automated Manual Transmission (AMT). Sometimes referred to as a semi-automatic transmission, this model combines manual clutches and transmissions with a range of actuators, sensors, processors and tires.

AMTs operate like automatic transmission while providing fuel savings and the economic advantages of a manual transmission. By this type of transmission, the driver can change gears manually or opt for an automatic transmission.

In any case, you do not need to use the clutch, which is operated by the hydraulic system.

History of the Automatic Transmission

General Motors and REO introduced semi-automatic transmissions for vehicles in 1934.

These models posed fewer challenges than a standard manual transmission but still had to use a clutch to change gears. GM’s transmission was the first of its kind to use a hydraulically operated planetary transmission, allowing speeds to vary based on the vehicle’s ground speed.

The planetary transmission was amongst the most relevant events on the way to a modern automatic transmission. Although GM was the first to use a version with hydraulic controls, this technology actually dates back to Wilson-Pilcher’s 1900 invention.

This innovation consisted of four gears on two trains which could be moved with a single lever.

Automatic Transmission Operation

The most typical type of automatic transmission uses hydraulic power to change gears. According to How Stuff Works, this device connects a torque converter or fluid clutch with gears that provide the desired speed range for the vehicle.

The torque converter combines the engine to the transmission and uses pressurized fluid to transfer power to the gears. This device replaces the manual friction grip and allows the vehicle to come to a complete stop without stopping.

The Art of Manliness data describes the operation of the automatic transmission. When the engine transmits power to the torque converter pump, the pump converts that power into transmission fluid that powers the torque converter turbine.

This device increases the power of the fluid and transmits even more power to the turbine, creating a rotating vortex that turns the turbine and the connected central shaft. The power generated by this rotation is transmitted from the shaft to the first epicyclic gear.

This type of transmission has what is termed hydraulic steering. The pressurized pump oil has an oil pump, which allows the speed to be changed depending on the vehicle speed, the speed of the tires per minute and other factors.

The gear pump is located between the epicyclic gear train and the torque converter, where it sucks and pushes the transmission fluid from the bearing.

The pump inlet leads directly to the torque converter housing connected to the flexible motor board. When the engine is not functioning, the transmission does not have the oil pressure required to work, so the vehicle cannot be pressurized.

A planetary gear train is a mechanical system in which a set of belts and clutches connects the gears. As the driver changes gears, the belts maintain a fixed gear while rotating the other to transmit engine torque and increase or decrease gears.

Different gears are sometimes referred to as planetary gears, ring gears, and planetary gears. The arrangement of the gears determines the amount of power that will be transferred from one stage to another and into the driving of the vehicle.

Automatic Transmission Gears

Automatic transmission gears include the list below:

  • As stated by How a Car Works, when you put the vehicle into gear, it includes all available forward gears. This means that the transmission can be shifted through the full range of gears as needed. Six-speed automatic transmissions are the most frequent number of gears, but older cars and compact beginner cars may have four or five automatic speeds.
  • The third gear locks the transmission into third gear or limits it to first, second and third gears. This gives the power and traction needed to go up a hill or tow a boat, caravan or trailer. When the engine reaches the set speed per minute (rpm), most vehicles will automatically lower the third gear to prevent damage to the engine.
  • The second gear locks the transmission in the second gear or the gear limit of first and second gears. This equipment is ideal for going up and down slopes in slippery conditions, as well as for driving on ice, snow and other types of bad weather.
  • First gear is utilized when you want to clasp the transmission in first gear, although some vehicles automatically disengage from that gear to protect the engine at certain rpm’s. Like second and third gears, this gear is best used for towing, driving uphill or downhill, and when travelling in slippery and icy conditions.

Benefits of an Automatic Transmission

According to How Stuff Works, the most significant benefit of an automatic transmission is the strength to drive without the requirement for a clutch, as is required with a manual transmission. People with many disabilities can drive automatically because the surgery only requires two useful limbs.

Clutch failure also eliminates the need to manually pay attention to gear changes and monitor the attachment to make necessary changes, giving you more attention to focus on the task of driving.

Many drivers also find it easier to operate an automatic transmission at low speed than a manual transmission. The hydraulic automatic transmission creates a creep phenomenon, which encourages the vehicle to move even at idle.

While the gearboxes don’t require as much maintenance as the engine, they still get a little love. Be sure to check the transmission fluid level with each oil change and, if your vehicle’s maintenance schedule recommends it, change the transmission fluid on demand.

Most transmissions include radiators to regulate the fluid temperature, but if you tow the vehicle frequently, consider adding a heavy-duty radiator if yours isn’t equipped for higher workloads.


Have your vehicle check if the transmission squeals or makes noise, if you feel yourself slipping, if you are hesitant to accelerate or change gears, if you see red fluid running under your vehicle, or if you notice a burning smell.

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