Ravigneaux planetary gearset

A Ravigneaux gearset is a special double planetary gear, which is commonly used in automatic transmissions. It is named after the French inventor pole Ravigneaux who introduced it mid-1930 in Neuilly -sur -Seine.

Components

It consists of:

• A common ring gear ( gray), which is connected via the differential to the driven wheels
• A common carrier ( red)
• Two different sized sun gears (green and dark green)
• Short ( dark red ) and long (light red ) planetary

Function

The Ravigneaux set is the basis for most four- speed automatic transmission. With additional planetary he can also be found in many automatic transmissions with 5,6,7 or 9 gears. The different gear ratios can be achieved as in the simple planetary gear by driving and hard braking certain parts or by Beblockung the entire planetary gear set. The output can be performed either via the ring gear or the planet. The drawing shows an output on the ring gear. For shifting gears must the motor shaft (white gear ) are connected with one of the sun gears or the planet over the large brakes (green ) sun or the Planetenradträgerring (red) are held and couplings. This results in the transition table after six meaningful combinations according to the four forward gears, one reverse gear and give an idle.

By varying the number of teeth of the gears involved in the translation can be achieved changed. A special feature is the third gear dar. where any two couplings are switched simultaneously, so that the transmission is locked, regardless of the number of teeth still the translation results one.

Usually, three short and three long planet gears are used. But it would also be conceivable for other numbers. The number of planet does not affect the translation, but rather an effect on the maximum transmissible torque.