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Old 30th July 2007, 12:15   #1
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Default Why don't we have air suspension in cars ?

(Moderators please move the thread to appropriate group if this is not the correct group.)

Many of us must have been traveled using volvo buses, the air suspension provided by those buses is much better than our normal cars.

My question is , what is stopping all the car manufactures to put it in car? Looking at the current road conditions , it will be definitely boon for most of the people.
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Old 30th July 2007, 12:29   #2
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I am not too sure but then it will affect high speed handling of the car.. Sturdy suspension helps in handling..
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Old 30th July 2007, 12:35   #3
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Originally Posted by neoonwheels View Post
I am not too sure but then it will affect high speed handling of the car.. Sturdy suspension helps in handling..

But those buses easily cross 140+ mark , so may not be security issue. If I am not wrong cadillac also has air suspension.

So why not in india ?
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Old 30th July 2007, 12:37   #4
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I think the primary reasons are cost & complexity. Given our extremely price conscious market it doesn't make much sense for manufacturers to give us air suspension since this will drive the cost of cars much higher.

Secondly, these suspension systems are quite complex at best & it would be pretty hard to find good engineers to repair them if something goes wrong, which would mean additional training etc. to mechanics which is easier said than done.

Also, even worldwide small cars do not feature air suspension, it is still a realm of cars like the E-class & above, so don't expect our City's or SX4's to feature air suspension anytime soon.

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Originally Posted by neoonwheels View Post
I am not too sure but then it will affect high speed handling of the car.. Sturdy suspension helps in handling..
Then why do you think cars like the S63 AMG feature air suspension when they can go upto 300kmph (unrestricted)?
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Old 30th July 2007, 13:08   #5
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The Merc S-Class (W220 onward) featured an air-suspension. As iraghava pointed out, cost and complexity are the primary reasons for the majority of cars not having it.
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Old 30th July 2007, 13:10   #6
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What about gas filled shock absorbers? (innova, I think...)
Are they a flavor of air suspension?

And which gas do these use?
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Old 30th July 2007, 13:22   #7
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Quote:
Originally Posted by hrishig View Post
But those buses easily cross 140+ mark ,
No way.... As far as I know the top speed of Volvo B7R is between 100-110km/hr.

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Originally Posted by neoonwheels View Post
I am not too sure but then it will affect high speed handling of the car.. Sturdy suspension helps in handling..
I think its more to do with the weight the buses carry.Normal suspensions like leaf plates will certainly take the weight, but will give a bumpy ride.

Last edited by mail4ajo : 30th July 2007 at 13:23.
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Old 30th July 2007, 13:25   #8
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Quote:
Originally Posted by anandpadhye View Post
What about gas filled shock absorbers? (innova, I think...)
Are they a flavor of air suspension?

And which gas do these use?

i think gas filled shocks may not be same as air suspension bcos even bikes like pulsar and enfied have those..

i think air suspension refers to an air balloon/membrane on which the body floats . this holds air and the air itself acts as the spring unline a gas filled shocks where the gas provides the damping alone...
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Old 30th July 2007, 13:26   #9
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I guess gas-filled shocks don't count, since the 'suspension' is still a good old coil spring one.

Yes, the air suspension would add too much complexity (compressor system + electronics) to upset the cost-benefit ratio of a small/mid-size car. For buses, trucks and Mercs/AMGs that cost is a very small percentage.

Citroen had justified air suspension by the "ride height" logic (roads in rural France were not that good then) - low for stable high-speed handling, high for bumpy undulating roads. "Ride comfort" was a fringe benefit (not that conventional spring-shock combo cannot be tuned to give that).

Air suspension in buses and trucks have a different justification (again, ride comfort is only a fringe benefit):
* "Kneeling" function - to bring the lowest step down to curb level to make it easy for elderly and physically-challenged to climb in easily
* Chassis / Load-bed levelling in assymetrical loading situations, to improve vehicle handling
* Matching the Load-bed to loading platform height for easier RO-RO of loads
* Reducing chassis height for lesser air-drag while cruising at 90-110Kmph (no, not valid for Indian highways - only a Bose electric suspension would help there)

Last edited by DerAlte : 30th July 2007 at 13:32.
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Old 30th July 2007, 13:44   #10
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Quote:
Originally Posted by anandpadhye View Post
What about gas filled shock absorbers? (innova, I think...)
Are they a flavor of air suspension?

And which gas do these use?
I don't think gas filled shock absorbers comes under air suspension.


Regarding the cost factor,

But I remember talking to one person in auto exhibition in pune ( 2006 near RTO ) , He had air suspension even for almost every vehicle even for bicycle.

Don't know what happend that. But looking at the technical advancements that are happening round the clock , I think this should be comparatively easy
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Old 30th July 2007, 16:00   #11
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Quote:
Originally Posted by DerAlte View Post
Citroen had justified air suspension by the "ride height" logic (roads in rural France were not that good then) - low for stable high-speed handling, high for bumpy undulating roads. "Ride comfort" was a fringe benefit (not that conventional spring-shock combo cannot be tuned to give that).
Yes sir, but we both know the associated problems with Citroen suspensions where long-term life was concerned. Even today they are not 100% reliable when compared to the good old coil springs.

And it was a Hydropneumatic system, first introduced on the DS, which I love, as can be seen from my avatar!

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Originally Posted by hrishig View Post
Don't know what happend that. But looking at the technical advancements that are happening round the clock , I think this should be comparatively easy
It's not that easy Girish, there are a lot of electrics involved which can & do go wrong.
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Old 30th July 2007, 16:37   #12
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How fool I am ... . I thought only the handling would be an issue... About Volvo bus, max speed is 100 KMPH i guess.. ya but then thanks guys for correcting me..
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Old 30th July 2007, 17:54   #13
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Quote:
Originally Posted by DerAlte View Post
Air suspension in buses and trucks have a different justification (again, ride comfort is only a fringe benefit):
* "Kneeling" function - to bring the lowest step down to curb level to make it easy for elderly and physically-challenged to climb in easily
* Chassis / Load-bed levelling in assymetrical loading situations, to improve vehicle handling
* Matching the Load-bed to loading platform height for easier RO-RO of loads
* Reducing chassis height for lesser air-drag while cruising at 90-110Kmph (no, not valid for Indian highways - only a Bose electric suspension would help there)
Trucks have air brakes which means a compressor already exists onboard. Makes the tradeoff much easier to justify. A huge weight savings compared to leaf springs as well.
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Old 30th July 2007, 21:02   #14
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Quote:
Originally Posted by Mpower View Post
Trucks have air brakes which means a compressor already exists onboard. Makes the tradeoff much easier to justify. A huge weight savings compared to leaf springs as well.
All trucks anywhere have mechanical suspension rather than a pneumatic one. Instead the cab is actually suspended on Pneumatic stilts.
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Old 30th July 2007, 21:11   #15
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Quote:
Originally Posted by 1100D View Post
All trucks anywhere have mechanical suspension rather than a pneumatic one. Instead the cab is actually suspended on Pneumatic stilts.
All Class 8 trucks in the US and Western Europe are 100% air suspension in the rear tandem axle and all trailer axles. Only the front suspension is mechanical. Intercity coaches and large RV are also air. Next time you see a big rig, take a peek
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