2.  Hydro pneumatic suspension system
 Use of additional electronic sensors and driver
control of suspension performance
 Softer springs – better damping of road forces and
superior driver comfort
 But it also leads to collapse under given weight in
case of heavy vehicles.
 Balancing of Both Handling & Comfort.

3. When The Vehicle goes into potholes or bump, the
Suspension geometry changes.
On loading ground clearance decreases.
Unequal braking effort generated.
Resonance frequency vary as per the changing
stiffness of the suspension system.
While cornering, vehicle rolls about its longitudinal
axis.
Cant keep the tyre contact with ground at all time.
Loss of traction on bump and dips.
Vehicle becomes dynamic unstable at high speed.

4.  To overcome problems of conventional
suspension system
 Better load distribution per axle
 Decreases overload problem
 Increases ride comfort

5. 1] A standard Citroën sphere
2] A hydraulically controlled isolation valve
3] A ball and piston valve
4] Two damping elements
5 ]An electrically controlled valve

6. 1. uses an inert gas, nitrogen (colored
blue) as spring medium
Principle- Exactly the opposite of Boyle’s Law!
2. The flexibility of gas decreases as
What does Boyle’s Law Say?
increasing load compresses
By keeping the mass of the gas constant and changing the volume
suspension pistons
of its container, its pressure can be controlled.
3. Leading to reduction in volume of gas
and adding to its pressure
For a pneumatic system- Air/gas is admitted or withdrawn from
the system by compressors and exhaust valves, modifying its mass 4. Damping effect is obtained by forcing
while keeping the volume constant.
fluid through two way restrictor
between cylinder and piston

8. ADVANCEMENT IN SUSPENSION
Coming soon….
Conventional Spring System
HYDRACTIVE 1
Hydro pneumatic
HYDRACTIVE 2
Hydractive
HYDRACTIVE 3
HYDRACTIVE 4

9. FIRST GENERATION- HYDROACTIVE 1

10. SECOND GENERATION- HYDROACTIVE 2

11. THIRD GENERATION- HYDROACTIVE 3
HYDROACTIVE 3 +
Features
• guarantees a constant ride height regardless of
the load or number of passengers
1.Fluid pump independent of engine and
electric
• lowering the car at speeds above 110 kmh to
optimize stability and fuel economy.
2. Computer supervises the car body height
selection
• On rough roads, it automatically raises for
increased clearance and comfort.
• The Hydractive III+ suspension system is
maintenance free for 5yrs/200,000kms.
• Similar to hydractive 2.

12. NEXT GENERATION- HYDROACTIVE 4
Hydractive 4 will offer
1. Dynamic Leveling
2. Each wheel will have separate height
corrector & Pair of sphere.
3. Each wheel be able to independently switch
between a firm and soft setting.
ADVANTAGE
Body roll is kept to an absolute minimum
leading dynamic leveling, preventing pitch , yaw
& roll.

13. ADVANTAGES
 Ground clearance can be kept constant under any load
variation.
 Suspension geometry of the vehicle remains same in
dynamic condition.
 Because of this system, it keep the vehicle in contact with
the road at all time.
The failure of sensor can cause uneven vehicle
dynamics
Major Precaution should be taken while changing
the tyres.
Costly compared to conventional suspension
system.
 No need of Anti-Roll bar in vehicle.
 Hydractive suspension system is maintenance free till 5
years.
 Increases the dynamic stability of vehicle by lowering the
ride height when the vehicle speed increases above 110
km/hr.
 Well packaged system leading to optimum space utilisation
 Hydractive Suspension is the need of todays automobile.
 Handling & comfort can be achieved in todays need.

14.  Citroen Technical Guide.
 http://en.wikipedia.org/wiki/Hydropneumatic_suspension
 http://www.carbibles.com/suspension_bible_pg3.html
 http://www.citroencarclub.org.uk/drupal/node/36
 http://www.citroenet.org.uk/miscellaneous/hydraulics/hydraulics-16.html
 http://www.citroen.com.au/citroen-universe/technology/comfort/hydractive-iii-plus-suspension
 http://www.autozine.org/technical_school/suspension/tech_suspension3.htm
 http://citroen.tramontana.co.hu/suspension/various-suspension-systems
 http://www.myweb.com.au/citroen/cit_tech_hydropneu.htm