ground clearance AUDI A6 ALLROAD 1999 C5 / 2.G Pneumatic Suspension System

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The 4-level air suspension system in the allroad quattro is a logical development of the self-
levelling system in the Audi A6.
The principles of the suspension/air suspension system and the description of those system
components which are identical in the 4-level air suspension system are described in SSP 242.
The contents of this self-study program are supplementary to the contents of SSP 242.
The 4-level air suspension system in the Audi allroad quattro

Introduction
Designing a vehicle this perfect for on and
off-road use sounds like squaring the circle.
Usually the strengths of an off-road vehicle
are decided weaknesses when it comes to
road use.
A high ground clearance, crucial for rough
terrain, gives the vehicle a correspondingly
high centre of gravity.
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When it comes to fast cornering, however,
this is as disadvantageous as it is for driving
stability at higher speeds. In addition, the air
resistance is increased, which significantly
affects fuel consumption.
In contrast, the shorter spring travel and the
firmer running gear matching of an “on-road
running gear” offer inadequate driving
comfort off-road.
A variable ground clearance is the solution for
all road use and it’s called
4-level air suspension
.
The air suspension realised in the allroad
quattro is based on the familiar self-levelling
system of the Audi A6.

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The 4-level air suspension system is designed
as what is known as a pressure accumulator
system.
The pressure accumulator system increases
system availability, reduces noise
development and protects the power supply.One of the special features of the system is
the ability to alter the ground clearance by 66
mm in 4 stages. The 4 stages can be
controlled manually or automatically (see
page 7 onwards).
The levels are designated as follows:
Level 1 = low level (
LL)
Level 2 = normal level (
NL
)
Level 3 = high level 1 (
HL1)
Level 4 = high level 2 (
HL2)
Parking level
PL
= high level 1
High level 2 (HL2)
+41 mm from normal
level Ground clearance
208 mm
High level 1 (HL1)
+25 mm from normal
level
(=parking level)
Normal level (NL)
± 0 mm
Low level (TL)
-25 mm from normal
level Ground clearance
192 mm
Ground clearance
167 mm
Ground clearance
142 mm
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Description of the system
• The 4 level stages can be controlled
manually or automatically within defined
limits (see page 8 onwards).
• Individual automatic functions or the
entire system can be switched off via the
control system.
• LEDs in the operating unit indicate the
operating status and the control
procedures to the driver.
• Pressure accumulator system for
maximum comfort. The newly developed fully-supporting air
suspension system on all four wheels was
designed specifically for the allroad quattro .
As well as the advantages of air suspension-
based self-levelling, as described for the A6
(see SSP 242), this system offers additional
benefits.
• The 4-level air suspension is a
sophisticated electronically controlled air
suspension system at both axles. The
system enables variation of the floor level
by 66 mm and offers four defined height
levels with between 142 and 208 mm
ground clearance.
• Depending on the driving conditions and
requirements you can select greater
ground clearance or a low vehicle centre
of gravity and a good c
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value.
• The 4-level air suspension keeps the pre-
set vehicle level constant, regardless of
load and weight distribution.
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