Automatic Transmission Power Flow, Basic Function - GF27.10-P-1002A

Model all with transmission 725.0/1 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The designation "power flow" refers to the transmission paths of torques. The torque is transferred to the drive wheels through the mechanical-hydraulic connection between the combustion engine, electric machine (integrated starter alternator/hybrid vehicle electric motor), torque converter, downstream automatic transmission and the differential. Power is transferred in the torque converter via the driven impeller by diverting hydraulic fluid to the turbine wheel which is connected to the drive shaft. When the torque converter lockup clutch is engaged, power is transmitted via this mechanical connection. The gear wheels of the individual planetary gear sets forward the torques generated by the torque converter to the output shaft with the help of the multidisk clutches and multidisk brakes to match the transmission ratio and actuated shift elements. A reduction of the output speed in lower gears results in lower vehicle speeds with simultaneously higher tractive forces and torques at the drive wheels.

All planetary gear sets consist of the following elements: sun gear, planetary gears, planet carrier and annulus gear.

Function requirements 

• Ignition ON (circuit 15)
• Engine in operation

Function 

The function sequence is described in the following steps:

• 1st gear power flow 
• 2nd gear power flow 
• 3rd gear power flow 
• 4th gear power flow 
• 5th gear power flow 
• 6th gear power flow 
• 7th gear power flow 
• 8th gear power flow 
• 9th gear power flow 
• Power flow in reverse gear 

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 1st gear 

1st gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B05 multidisk brake
• B06 multidisk brake
• K38 multiplate clutch

  In 1st gear, the power flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP3

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of the planetary gear set P1 is connected through the multidisk clutch K38 (E) with the annulus gear of the planetary gear set P2. The multidisk brake B05 (B) brakes the sun gear of the planetary gear set P2. As a result, the torque increases and the rotational speed is decreased. The ring gear of the planetary gear set P2 has a mechanical connection to the sun gear of the planetary gear set P3. The planetary gears rotate in the ring gear of the planetary gear set P3 braked by the multidisk brake B06 (C) and the planet carrier of the planetary gear set P3 transfers the resulting increased torque and the reduced engine speed to the output shaft.

The output shaft thereby rotates with a reduced input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 2nd gear 

2nd gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B06 multidisk brake
• Multiplate clutch K81
• K38 multiplate clutch

  In 2nd gear, the power flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP3

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The multidisk clutch K81 (D) connects the drive shaft with the planet carrier of the planetary gear set P1 so that these revolve in the block. The multidisk clutch K38 (E) makes a mechanical connection with the sun gear of the planetary gear set P3. The multidisk brake B06 (B) brakes the ring gear of the planetary gear set P3. The planet carrier of the planetary gear set P3 transfers the resulting increased torque and reduced engine speed to the output shaft. The output shaft thereby rotates with a reduced input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 3rd gear 

3rd gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B05 multidisk brake
• B06 multidisk brake
• Multiplate clutch K81

  In 3rd gear, the power flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP3

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The multidisk clutch K81 (D) connects the drive shaft with the planet carrier of the planetary gear set P1 so that these revolve in the block. The ring gear of planetary gear set P1 is driven by the planet carrier of planetary gear set P1. In turn, the ring gear drives the planet carrier of the planetary gear set P2. The multidisk brake B05 (B) brakes the sun gear of the planetary gear set P2.

Consequently, power is transmitted to the sun gear of the planetary gear set P3 through the ring gear of the planetary gear set P2. The multidisk brake B06 (C) brakes the ring gear of the planetary gear set P3. The planet carrier of the planetary gear set P3 transfers the resulting increased torque and reduced engine speed to the output shaft. The output shaft thereby rotates with a reduced input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 4th gear 

4th gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B05 multidisk brake
• B06 multidisk brake
• K27 multiplate clutch

  In 4th gear, the power flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP3
• Planetary gear setP4

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of the planetary gear set P4 is also driven. The sun gear of the planetary gear set P2 is braked by the multidisk brake B05 (B). The ring gear of the planetary gear set P2 supports the sun gears of the planetary gear sets P3 and P4. The multidisk brake B06 (C) brakes the ring gear of the planetary gear set P3. The multidisk clutch K27 (F) is closed and the planetary gear set P4 is switched in. The planet carrier of the planetary gear set P3 and the ring gear of the planetary gear set P4 transfer the resulting increased torque and the reduced engine speed to the output shaft.

The output shaft thereby rotates with a reduced input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 5th gear 

5th gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B05 multidisk brake
• Multiplate clutch K81
• K27 multiplate clutch

  In 5th gear, the power flow flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP4

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of the planetary gear set P4 is also driven by the drive shaft. The multidisk clutch K81 (D) connects the drive shaft with the planet carrier of the planetary gear set P1 so that these revolve in the block. The ring gear of planetary gear set P1 supports the planet carrier of planetary gear set P2. The multidisk brake B05 (B) brakes the sun gear of planetary gear set P2. As a result, the ring gear of planetary gear set P2 transfers the power to the sun gear of the planetary gear set P4. Via the closed multiplate clutch K27 (F), the ring gear of planetary gear set P4 transfers the resulting increased torque and reduced engine speed to the output shaft. The output shaft thereby rotates with a reduced input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 6th gear 

6th gear power flow 

The following multidisk clutches are engaged:

• Multiplate clutch K81
• K38 multiplate clutch
• K27 multiplate clutch

  In 6th gear, the power flow flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP4

The planet carrier of the planetary gear set P4 is driven by the drive shaft. The multidisk clutches K81 (D) and K38 (E) connect the respective elements of the planetary gear sets P1 and P2. As a result, these revolve in the block and support the sun gear of planetary gear set P4. Via the closed multidisk clutch K27 (F), the ring gear of planetary gear set P4 transfers the torque to output shaft. The output shaft rotates with the input speed in the of engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 7th gear 

7th gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B05 multidisk brake
• K38 multiplate clutch
• K27 multiplate clutch

  In 7th gear, the power flow flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP4

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of the planetary gear set P4 is also driven by the drive shaft. The ring gear of planetary gear set P1 supports the planet carrier of planetary gear set P2. The ring gear of planetary gear set P1 is driven by the planet carrier of planetary gear set P1. The multidisk brake B05 (B) brakes the sun gear of the planetary gear set P2. As a result, the ring gear of planetary gear set P2 transfers the power via the closed multiplate clutch K38 (E) to the sun gear of planetary gear set P4. Via the closed multiplate clutch K27 (F), the ring gear of planetary gear set P4 transfers the resulting reduced torque and increased engine speed to the output shaft. The output shaft thereby rotates with an increased input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 8th gear 

8th gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B08 multidisk brake
• K38 multiplate clutch
• K27 multiplate clutch

  In 8th gear, the power flows via the following gear sets:

• Planetary gear setP1
• Planetary gear setP4

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planetary gear carrier of the planetary gear set P4 is also driven by the drive shaft. The planet carrier of the planetary gear set P1 is braked by actuation of the multidisk brake B08 (A). The sun gear of the planetary gear set P4 is connected with the planet carrier of the planetary gear set P1 through actuation of the multidisk clutch K38 (E) and also braked. Via the closed multiplate clutch K27 (F), the ring gear of planetary gear set P4 transfers the resulting reduced torque and increased engine speed to the output shaft. The output shaft thereby rotates with an increased input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown is power flow in 9th gear 

9th gear power flow 

The following multidisk brakes and multidisk clutches are engaged:

• B08 multidisk brake
• B05 multidisk brake
• K27 multiplate clutch

  In 9th gear, the power flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP4

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of the planetary gear set P4 is also driven by the drive shaft. The planet carrier of the planetary gear set P1 is braked by actuation of the multidisk brake B08 (A). The power flow runs via the ring gear of the planetary gear set P1 to the planet carrier of the planetary gear set P2. The multidisk brake B05 (B) brakes the sun gear of the planetary gear set P2. The ring gear of the planetary gear set P2 drives the sun gear of the planetary gear set P4.

Via the closed multiplate clutch K27 (F), the ring gear of planetary gear set P4 transfers the resulting reduced torque and increased engine speed to the output shaft. The output shaft thereby rotates with an increased input speed in the engine's rotation direction.

Courtesy of MERCEDES-BENZ USA

Shown power flow for reverse gear 

Power flow in reverse gear 

All planetary gear sets consist of the following components: Sun gear, planetary gears, planet carrier and ring gear.

The following multidisk brakes are engaged:

• B08 multidisk brake
• B05 multidisk brake
• B06 multidisk brake

  The power flow in the reverse gear flows through the following gear sets:

• Planetary gear setP1
• Planetary gear setP2
• Planetary gear setP3

The sun gear of the planetary gear set P1 is part of the drive shaft and is driven by this. The planet carrier of planetary gear set P1 is braked by the multidisk brake B08 (A). The power flow runs via the ring gear of the planetary gear set P1 to the planet carrier of planetary gear set P2. The planet carrier of planetary gear set P2 roll on the sun gear of planet carrier of planetary gear set P2 braked by the multidisk brake B05 (B). The ring gear of the planetary gear set P2 drives the sun gear of the planetary gear set P3. The multidisk brake B06 (B) brakes the ring gear of the planetary gear set P3. The planet carrier of the planetary gear set P3 transfers the resulting increased torque and reduced engine speed to the output shaft. The output shaft subsequently rotates with reduced input speed against the direction of engine rotation.