Pic. 6.11. Planetary gear automatic transmission: 1 - driven element; 2 - blocked element
The basis of the automatic transmission is the so-called planetary mechanism. It consists of a gear (sun gear), around which three other gears revolve (satellites). The design is closed by an external gear wheel with an internal arrangement of teeth (ring gear). Unique way to connect gears. In a planetary gear, all gears are in constant mesh. Stepped transmission occurs without breaking the flow of torque due to the blocking and inclusion of free play of satellites, sun and ring gears (pic. 6.11).
Gear shifting thus takes place without interruption in the power flow. Blocking and starting are carried out by multi-disc brakes and hydraulic clutches. On a multi-stage automatic transmission, three planetary gears are installed in a row. This is how the automatic transmission is arranged with three forward and one reverse gears.