citroën technical training zf 4hp20 automatic transmission

37Chapter 6II -FUNCTIONTo transmit the movement supplied by the planet wheel carrier of gear train N° 1to the drive wheels.Movement is transmitted as follows:• The movement leaves the planet wheel carrier n° 1 and is received by the inputgear (12) of the step-down gear,• This transmits the movement to a secondary shaft (4) through the output gear(1) of the step-down gear,• The secondary shaft transmits the movement to the crown wheel (5) of thedifferential through its drive pinion (3).Final drive composition:Step-down gear: This transmits the output torque from the epicyclic gear train tothe return shaft (secondary line) and increases the movement(61 x 66 ratio). It is positioned in the middle of the transmissionso as to reduce gearing noises. Its secondary shaft is guided bytwo tapered bearings with adjusting shims.Final drive gear: This provides the link between the secondary return shaft andthe differential. In addition, it increases movement (20 x 69ratio).Differential:This is of standard design and has two planet wheels. Ittransmits the transmission movement to the wheels.The differential unit is guided by two X layout tapered bearingswith adjustments on the mechanism housing side.The sunwheels are used to seal the transmission on their outerdiameter and provide a seal inside by means of a plug.Assembly of the driveshaftsRight hand driveshaft → mounted on a bearingLeft hand driveshaft → locked by a springZF 4HP20 AUTOMATIC TRANSMISSION© AUTOMOBILES CITROËN Toute reproduction ou traduction même partielle sans l'autorisation écrite d'AUTOMOBILES CITROËN est interdite et constitue une contrefaçon