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Example illustration |
1 | Electric parking brake actuator motor |
Overview
This document contains information on:
General
Function
General
The left and right electric parking brake actuator motors push each of the brakepads against the corresponding brake disk after activation of the electric parking brake (EFB). The vehicle is therefore secured against rolling away.
The left and right electric parking brake actuator motors are located on each brake caliper towards the vehicle center.
Overview of electric parking brake actuator motor |
1 | Left electric parking brake actuator motor |
2 | Spindle drive with thrust nut |
3 | Brake piston |
4 | Dust boot |
5 | Brake disk |
6 | Frame |
7 | Brake linings |
8 | Brake caliper |
9 | Brake piston seal |
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Power is transmitted from the actuator motor (1) to the epicyclic gear system (12) of the spindle drive via a toothed belt (11) between the actuator motor (1) and the epicyclic gear system belt pulley (10).
Function
Overview of electric parking brake actuator motor |
1 | Electric parking brake actuator motor |
10 | Planetary gear system belt pulley |
11 | Toothed belt |
12 | Planetary gear system |
13 | Electrical connector |
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Parking brake in applied state |
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Parking brake in applied state
After activation of the electric parking brake, the left and right electric parking brake actuator motors are supplied with voltage. Via the spindle drive with thrust nut on the respective brake piston, the brakepads press against the corresponding brake disk. The spindle drive's self-locking feature prevents any reduction in application force and therefore any reduction in brake force after activation of the actuator motors is over.
Parking brake in released state |
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Parking brake in released state
To release the EFB, the polarity of the actuator motor operation is changed. The respective spindle drive with thrust nut rotates in the opposite direction. In doing so, the required clearance is adjusted and brake pad wear is taken into account.
Brake piston fully extended (brakepads and/or worn brake disks) |
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Brake piston fully extended (brakepads and/or worn brake disks)
If the brakepads and/or brake disks on the rear axle are worn, the piston is almost fully extended via the spindle drive with thrust nut. This guarantees that the contact pressure between brakepads and brake disks is sufficient in the locked state.
To change the brakepads or brake disks, the left and right electric parking brake actuator motors are actuated by the ESP® control unit until the brake pistons are in the assembly position. The brake pistons are then completely is retracted.
The "EFB assembly position" function can be activated or deactivated using Xentry Diagnostics or via the workshop menu in the instrument cluster.