Power flow in reverse gear, transmission mode "S", function - GF27.10-P-3030AHO

TRANSMISSION 724.2 in MODEL 212 

Fig 1: Transmission Reverse Gear Power Flow Diagram

Courtesy of MERCEDES-BENZ USA

Function requirements for power flow in reverse gear in transmission mode "S", general 

• Circuit 87 (connected circuit 15) ON
• Internal combustion engine running and/or electric machine (A79/1) ON

Power flow in reverse gear, transmission mode "S", general 

The following multidisk brakes and multidisk clutches are engaged:

• Multidisk brake BR (41)
• Multidisk brake B1 (42)
• Multidisk clutch K3 (48)

In reverse gear with transmission mode "S", the power flows through the following gear sets:

• Ravigneaux gear set 
• Rear single planetary gear set 
• Front single planetary gear set 

Ravigneaux gear set 

The small ring gear (5) is driven via the transmission input shaft. The long planetary gears (50) roll over the stalled sun gear (7) and transmit the increased torque and reduced rotational speed as a result to the dual planet carrier (6).

Rear single planetary gear set 

The ring gear (9) rotates at the same speed due to the mechanical connection to the dual planet carrier (6). The planetary gears (51) roll on the sun gear (11). Due to the stalled planet carrier (10), the rotational direction of the sun gear (11) reverses.

Front single planetary gear set 

There is a connection between the sun gear (14) and sun gear (11) via the engaged multidisk clutch K3 (48). As a result sun gear (14) rotates at the same speed and direction of rotation as sun gear (11) and drives the planetary gears (52). The increased torque and reduced rotational speed as a result are transmitted via the planet carrier (13) to the transmission output shaft. The transmission output shaft thus rotates at reduced transmission input speed opposite to the direction of the engine.