The EPB (Electric Park Brake) uses electric signals to individual brake caliper motors rather than a cable system. It has functions like Drive Away Assist and Automatic Hold. The EPB actuator has three main parts - an electric motor, gear train, and spindle drive.

1. The EPB (Electric Park Brake) is an alternative
system to the conventional manual park brake.
Rather than using a lever or pedal to pull a
cable, putting the vehicle in park, an EPB sends
an electric signal to individual motors in the
brake calipers to park the vehicle.
Fig. 3: EPB actuator (with caliper), and switch
Some EPB functions are:
• Drive Away Assist
• Automatic Hold
• Emergency Braking
• Exact Clamp Force Application
The actuator is comprised of three main parts:
electric motor, gear train, spindle drive
ZF TRW | Koblenz
Internship Experience Summary
Summer, 2016
John Lee
ZF TRW, a division under its parent company,
ZF, is a developer and producer of active and
passive safety systems:
Active Safety Systems:
• Technology used to assist the prevention of a
crash (brake assist, traction control, ABS, etc.)
Passive Safety Systems:
• Technology used to minimize damage to the
occupant during a crash (deformation zones,
seat belts, anti-shatter windshields, etc.)
ZF TRW provides driver-assist and semi-
automated safety functions such as:
• Adaptive cruise control
• Blind spot detection
• Lane keeping and change assist
• Emergency brake and steering assist
• Slip control
• Automatic parking break control
ZF TRW has facilities in more than 22
countries, with its headquarters in Livonia,
Michigan.
Fig.1 & 2: Examples of ZF TRW safety systems
Left: Electronic Slip Control
Right: Electrically powered hydraulic steering
Fig.4 & 5: EPB Actuator Components
Left: Motor and Gear Train
Right: Spindle Drive (not to scale)
Gear Train Ratio Analysis
•Performed gear ratio calculations and documented
accurate gear ratios of EPB actuators in production
Aliasing Analysis
•Assisted with calculations and virtual simulations to
estimate the effect of signal processing on the motor
Fig. 6: Affect of a sampling rate close to the signal’s frequency
(source: Indiana University Introduction to Computer Music Vol. 1)
Actuator NVH (Noise, Vibration & Harshness) Prediction
•Analyzed EPB actuators for potential noise from
rotation and gear meshing
Actuator Temperature Function Test Prediction
•Assisted in formation of analysis tools to predict
behavior of EPB actuators as the actuator temperature
changes
EPB DepartmentCompany Description My Projects
ZF Friedrichshafen AG
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WeightedSum(RelativeLoudnessEstimate)
Frequency Bands
1/3 Octave Band Frequency Analysis: Loudness Estimate
Audible Frequency Range (20Hz - 20kHz)