The principle of operation and the automatic transmission (automatic gearbox)

Automatic transmission is one of the varieties of automotive transmissions, which provides the transmission of the motor torque to the wheels. The main feature of this box is that it selects and switches gears without driver intervention, according to the current driving conditions. In today's article, we will try to find out all the features of automatic transmission, the device and the principle of operation.

The classic automatic transmission consists of the following parts:

• Hydraulic coupling. This detail is the most complex and indispensable in the operation of the automatic box. It is she who passes the torque from the ICE to the wheels. It is located between the transmission and the engine.
• Planetary gearboxes. Their function is also to transfer the engine power to the car's drive. The only difference is that the planetary gearboxes carry out an indirect transfer of the power moment (the hydraulic coupling acts directly).
• Friction clutch. Switches the transmission by disconnection and communication of the automatic transmission elements.
• Overtaking clutch. It is designed to reduce the impact in the previous mechanism when switching the car's speeds.
• Connecting shafts and drums.

Principle of operation and device automatic transmission

This transmission consists of a set of spools, directing the flow of transmission oil to the friction clutch and the pistons of brake bands. The spool position is set using the selector lever. Thus, after switching on a certain mode ("Drive" for example) of the gearbox and pressing the accelerator pedal, the engine transfers its power to the wheels, while a number of gears are involved in the operation (in the section on the second photo, their construction is visible). This is the principle of operation and the device automatic transmission.

It is also worth noting that the automatic box is divided into two categories according to the principle of action:

• Hydraulic devices.
• Electronic.

The first type has the following operating principle and the automatic transmission device. Here, the oil pressure is used from the centrifugal regulator by hydraulic automatics. The regulator, in turn, is connected to the output shaft of the automatic transmission. In addition, in hydraulic oil supply is activated when the driver presses the gas pedal. The gearbox then receives information about its position, as a result of which the spools are switched and further movement or stoppage of the car.

As for electronic automatics, here the principle of operation and the automatic transmission device is the use of solenoids that move the spools in the transmission housing. The cables for these parts go to the electronic gearbox control unit. The last element decides to move the solenoid, taking into account the position of the gas pedal, the current vehicle speed and the position of the selector lever.

As you can see, both transmissions have a similar operating principle and device. And repair of automatic transmission, by the way, is also equally expensive for both boxes.