(Park Pawl, Detailed Information - GF27.10-P-1103B)

Model All with transmission 700.420/421/422/423 

Park pawl, shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Engagement using selector drum 
  • Redundant engagement 
  • Emergency-P version 

General 

The park pawl secures the vehicle to prevent it from rolling away inadvertently.

Function requirements 

• Engine management ON (circuit 87M)

Function 

The park pawl is actuated via the dual-clutch transmission control unit. The dual-clutch transmission control unit actuates the even gears actuator motor. This moves the selector drum (5) into the corresponding position.

Engagement using selector drum 

Engagement sequence (from Not P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

To engage the park pawl, the actuator motor for the even gears actuates the selector drum (5). A guide for the P and Not P position with axial end stops are installed in the curve of the selector drum (5).

Actuation of the actuator motor for the even gears rotates the selector drum (5) by approx. 300° so that the sliding block (6) slides into the P position guide of the selector drum (5). The P position end stop locks the sliding block (6).

The sliding block (6) is attached to a pivoting lever (4). Rotating the selector drum (5) clockwise causes the sliding block (6) to leave the theoretical curve and reverses the lever action (4).

With the reversal of the lever (4), the emergency lock (11) is transported in the clockwise direction. The emergency lock (11) rotates the operating shaft (7) with attached cam. The cam pushes the park detent toward the parking lock gear (8).

Disengagement sequence (from P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

During the disengagement procedure, the selector drum (5) is turned counterclockwise by approx. 300° so that the sliding block (6) slides into the Not P position guide of the selector drum (5) and is locked by the Not P position end stop.

Redundant engagement 

Engagement sequence (from Not P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

The selector drum (5) is in the Not P position and the locking lever (2) is closed.

The locking lever (2) opens if the park pawl lift solenoid is not actuated. The preloaded spring (1) in the emergency lock (11) relaxes as a result and the park pawl is engaged.

Park pawl engaged (P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

Disengagement sequence (from P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

The locking lever (2) moves toward its original position if the magnet is energized. The selector drum (5) is turned to the P position. This guides the piston out of the emergency lock (11) and preloads the spring (1). The locking lever (2) closes while the position of the locking pawl (9) remains unchanged.

The selector drum (5) is turned further into the Not P position and the park pawl is disengaged.

Emergency-P version 

Disengagement sequence (from P position), shown on transmission 700.4 

Courtesy of MERCEDES-BENZ USA

The park pawl lift solenoid is energized and pushes the double ball joint with sleeve away from the park pawl lift solenoid.

The movement unlocks the emergency lock piston (3) as follows:

• The emergency lock piston (3) located in the emergency lock (11) is preloaded by a spring (1).
• The preloaded spring (1) is activated by moving the double ball joint with sleeve away from the park pawl lift solenoid, i.e. the spring (1) relaxes and pulls the emergency lock piston (3) into the sleeve of the emergency lock (11).
• The emergency lock (11) is connected to the operating shaft (7). If the emergency lock piston (3) retracts into the sleeve of the emergency lock (11), the operating shaft (7) rotates and P is engaged.

Disengagement sequence (from P position), shown on transmission 700.4