Audi TT 2016 Introduction Manual page 45

Electro-mechanical power steering
(EPS)
In terms of its design, functional principle and service
operations, the electro-mechanical power steering
system is identical to the system already implemented in
the 2015 A3.
Operation
Depending on whether auto, dynamic or comfort mode is
selected, the system activates steering maps which provide
universal, dynamic or comfort-oriented power steering.
When individual mode is selected, the driver can freely
select one of three maps.
Progressive steering
The Audi TT receives progressive steering as standard.
Progressive steering is provided by a variable steering ratio
using a special rack spline geometry. The steering ratio is at
its highest when driving in a straight line and during minor
steering inputs around the center position. Rotation of the
steering wheel through an angle of about 14° produces a
steering angle of about 1° at the front wheels (steering
ratio of approximately 14). The ratio decreases with
increasing steering angle, and thus becomes more direct.
This gives the Audi TT agile and precise handling in city
traffic and on windy country roads with little steering
effort.
At large steering angles (for example, in inner-city areas or
when parking), the steering ratio is reduced to significantly
reduce steering effort for the driver. The diagram below
clearly shows that with progressive steering, the steering
wheel has to be moved much less in order to turn the front
wheels to full lock.
Reference
For more information about the electro-mechanical power steering (EPS), refer to
Audi A3 Running Gear and Suspension System.
Pinion angle (°)
Vehicle: Audi drive select
comfort
auto
dynamic
individual
This reduces amount of steering input required and gives
significantly better dynamics during sporty driving maneu-
vers.
Rack
Key:
Steering lock with progressive steering
Steering lock with conventional steering
Progressive steering in the Audi TT
Conventional steering in the Audi A3
eSelf-Study Program 960143, The 2015
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Steering pinion
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