Power Flow In 1ST Gear, Function

Fig 1: Power Flow In 1st Gear, Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Principal of power transmission in 1st gear

The torque coming from the torque converter is increased and transmitted to the output shaft (5) via the input shaft (1), involving all three planetary gear sets.

The following are not engaged:

• Front multi-disc clutch (K1).
• Center multi-disc clutch (K2).
• Center multi-disc brake (B3).

Front Planetary Gear Set 

The input shaft (1) drives the internal gear (V4). In drive mode the sun gear (V1) is supported via the locked freewheel F1 and in overrun mode via the engaged front multi-disc brake (B1) in the housing (B1). The planetary gears (V2) roll over the fixed sun gear (V1) and provide an increase in torque between the internal gear (V4) and the planet carrier (V3). The planet carrier (V3) moves at reduced speed in the direction of engine rotation.

Rear Planetary Gear Set 

The internal gear (H4) turns at a reduced speed because of its mechanical connection to the front planet carrier (H3). The sun gear (H1) is supported via the engaged rear multi-disc brake (B2) and in drive mode via the locked freewheel (F2), in overrun mode via the engaged rear multi-disc clutch (K3) in the housing. The planet gears (H2) roll over the fixed sun gear (H1) and provide an increase in torque between the internal gear (H4) and the planet carrier (H3). The planet carrier (H3) moves at a reduced speed in the direction of engine rotation.

Center Planetary Gear Set 

The ring gear (M4) is driven at the same speed as the rear planet carrier (H3) as a result of a mechanical connection. The sun gear (M1) is supported in the housing via the rear multi-disc brake (B2) (M1). The planet gears (M2) roll over the fixed sun gear (M1) and provide an increase in torque between the internal gear (M4) and the planet carrier (M3). The output shaft (5) connected to the planet carrier (M3) turns at a reduced speed in the running direction of the engine.

1. Torque Converter, Location/Task/Design/Function
   
   See TORQUE CONVERTER, LOCATION/TASK/DESIGN/FUNCTION  .
2. Planetary Gearset, Location/Task/Design/Function
   
   See PLANETARY GEAR SET, LOCATION/TASK/DESIGN/FUNCTION  .
3. Multi-Disc Brake, Location/Task/Design/Function
   
   See MULTIPLE-DISC BRAKE, LOCATION/TASK/DESIGN/FUNCTION  .
4. Multi-Disc Clutch, Location/Task/Design/Function
   
   See MULTI-PLATE CLUTCH, LOCATION/TASK/DESIGN/FUNCTION  .
5. Freewheel, Location/Task/Design/Function
   
   See LOCATION/TASK/DESIGN/FUNCTION OF FREEWHEEL  .