Unlike simple mechanical transmission in which parallel shaft and gear wheels connecting among themselves are used in automatic transmissions planetary transfers are in the majority used.

Advantages of planetary transfer consist in its compactness, use of only one central shaft and in the way of gear shifting which is carried out by blocking of one and unblocking of other elements of a planetary row.

In the car with simple mechanical transmission the driver for gear shifting is forced to squeeze out constantly and consistently a pedal of coupling and to release an accelerator pedal. Automatic transmission automatically switches transfers in due time. For this purpose it is enough to driver to manipulate only an accelerator pedal, pressing or releasing it. Planetary transfer provides equal, without breakthroughs, switching of speeds of the movement of the car without loss to engine capacity, pushes and blows which are usually associated with the moment of switching of transfer in mechanical transmission. The solar gear wheel is in the center. Satellites rotate around a solar gear wheel while it rotates around an own axis. The Koronchaty gear wheel covers satellites which support drove. All satellites rotate at the same time and in one direction.

Fig. 9.1. Interrelation of components of the transmission: 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – drove planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – leading gear wheel of the main transfer; 9 – drove the lowering main transfer; 10 – the satellite of the lowering main transfer; 11 – the conducted gear wheel of the main transfer; 12 – the conducted counter drive gear wheel; 13 – a solar wheel of the lowering transfer; 14 – forward gear wreath of planetary transfer

Fig. 9.2. Work of components of the transmission in a position of the D-3-2 selector (the 1st transfer): 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – drove planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – the satellite of the lowering main transfer; 9 – counter drive gear wheel; 10 – a solar wheel of the lowering transfer; 11 – forward koronchaty wheel of planetary transfer

Fig. 9.3. Work of components of the transmission in a position of the D-3-2 selector (the 2nd transfer): 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – the satellite of the lowering main transfer; 9 – the conducted counter drive gear wheel; 10 – a solar wheel of the lowering transfer; 11 – forward koronchaty wheel of planetary transfer

Fig. 9.4. Work of components of the transmission in a position of the D-3-2 selector (the 3rd transfer): 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – drove planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – the satellite of the lowering main transfer; 9 – gear wheel of the main transfer; 10 – the conducted counter drive gear wheel; 11 – a solar wheel of the lowering transfer; 12 – forward koronchaty wheel of planetary transfer

Fig. 9.5. Work of components of the transmission in a selector D position (the 4th transfer): 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – drove planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – the satellite of the lowering main transfer; 9 – the conducted counter drive gear wheel; 10 – a solar wheel of the lowering transfer; 11 – forward koronchaty wheel of planetary transfer

Fig. 9.6. Work of components of the transmission in a selector R position: 1 – back koronchaty wheel of planetary transfer; 2 – back satellite of planetary transfer; 3 – forward satellite of planetary transfer; 4 – drove planetary transfer; 5 – leading drive of the counter; 6 – entrance shaft; 7 – solar cogwheel; 8 – the satellite of the lowering main transfer; 9 – the conducted gear wheel of the main transfer; 10 – the conducted counter drive gear wheel; 11 – a solar wheel of the lowering transfer; 12 – forward koronchaty wheel of planetary transfer

Switching of frequency of rotation in planetary transfer happens when 2 of 3 elements of planetary transfer (a solar gear wheel, a koronchaty gear wheel, drove) are in certain conditions – are blocked or unblocked in various combination (fig. 9.1, 9.2, 9.3, 9.4,9.5, 9.6).

Work of components of the transmission depending on a position of the lever of the selector is given in table 9.1.