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Old 2nd May 2011, 19:38   #1
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Default Air vs Leaf suspension for Buses

Is it a bad idea to use air suspension on bad roads? (unpaved, potholes).

Iíve always been told that using air suspension buses on bad roads is asking for troubles because the air suspension system would get damaged very soon.
Air suspension would only be suitable for good roads. But is this really true? If you would just slow down (to 25-35 km/hr), on bad stretches, would there still be the risk of damage?

One thing I can imagine is that air suspension tends to have a larger amortization stroke than the more rigid leaf springs? So the risk increases that the chassis hits the ground, also because the ground clearance is generally less on buses with air suspension (correct me if Iím wrong here). But that would be a side effect. My question really is whether an air suspension system can be used on bad roads without getting damaged, or if itís really not designed for that.

My dilemma is that Iím looking for a bus that needs to run on a 600 km stretch, 500 of which is perfectly paved, but 100 km is unpaved and bumpy! Appreciate your expertise on this!
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Old 2nd May 2011, 22:42   #2
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Default re: Air vs Leaf suspension for Buses

They are obsoletely trouble free. As you will have mentioned around 100KM is bumpy this may slightly reduce the useful life but only marginally- as something to be paid off. But this is not to the extent that they completely damage the suspension/
The point of GC less in Air suspension buses is not true as suspension has nothing to do with this.
My view is you can Go head with Air suspension!
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Old 3rd May 2011, 07:10   #3
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Default re: Air vs Leaf suspension for Buses

@jeff

At the outset let me say, dont even think about not going for the air suspension. They just provide too much comfort especially on the worse sections of the road to leave out.

Your fears about air suspension life worsening as it gets used on bad roads, is true pretty much for all kinds of suspension. And true, air suspension may cause bottoming out and something from the underbody hitting the ground more often then with leafs, but happens only if you go very hard of a sharp bump/ditch.

It all depends on your driver. Just having air suspension does not meant that you can equate the bad road to a smooth road and just drive straight on going through pot holes at upto 70-80kmph. Which is what I have seen most drivers do. The air suspension will allow you to get a lot more comfort. But they tend to react much worse to heavy abuse. Take care a little, and you wont find any trouble at all.
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Old 3rd May 2011, 12:06   #4
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Default re: Air vs Leaf suspension for Buses

If I were a passenger in your bus, I would definitely like you to have air suspension better.

Unless the road is so bad that you end up bottoming up the suspension, the air suspension may actually last more (and cause the other systems in the bus to last more by reducing shock transferred to them) than any of its other brethren.

The problem will be getting a good driver who wouldn't take the improved suspension as a license to driver rashly even on good roads. I understand hiring and keeping good CV drivers is very hard, but if you're already in business you would know how to do that
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Old 3rd May 2011, 15:41   #5
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Default Re: Air vs Leaf suspension for Buses

Thank you very much Ashley, Julupani and Vina for sharing your thoughts! I pretty much hoped for such answers to be honest... This makes the decision to go ahead with air suspension a lot easier! Two questions about the air bellows though: do they have a typical life-cycle? Much depends on quality and on how the bus is used of course, I know, but just to get a rough idea: is this a component that should be (preventively?) changed every year or so, or should they last much longer? And 2nd: in case of a blow-out, can a trained mechanic replace an air bellow on the spot beside the road? Regards, Jeff
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Old 3rd May 2011, 17:23   #6
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Default Re: Air vs Leaf suspension for Buses

Cant really say how long a bellow would normally last, and how often you should change it. But I think they can be changed out on the road itself if you have a spare. It should not be a very big job at all.
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Old 3rd May 2011, 17:41   #7
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Default Re: Air vs Leaf suspension for Buses

No air suspension : You feel every imperfection on the road.
Air suspension: You feel imperfections on road are perfected .

Personal experience ^^^.
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Old 3rd May 2011, 18:38   #8
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Default Re: Air vs Leaf suspension for Buses

Quote:
Originally Posted by Jeff_3 View Post
Thank you very much Ashley, Julupani and Vina for sharing your thoughts! I pretty much hoped for such answers to be honest... This makes the decision to go ahead with air suspension a lot easier! Two questions about the air bellows though: do they have a typical life-cycle? Much depends on quality and on how the bus is used of course, I know, but just to get a rough idea: is this a component that should be (preventively?) changed every year or so, or should they last much longer? And 2nd: in case of a blow-out, can a trained mechanic replace an air bellow on the spot beside the road? Regards, Jeff
You can check the lifecycle with the manufacturer - these are two of them that provide aftermarket for small vehicles (also for large vehicles):

Air Lift - Suspension Innovation Since 1949
Airide ™ spring air suspension - Firestone Industrial Products

the first actually provides a "helper bellow" to be put inside of coil springs to smooth out the ride and regain the ride-height in case of rear-loading. That one carries a lifetime warranty.


You'll probably have to do periodic checks and take some precautions (cleaning, visual inspections, no corrosive material or stones lodged) but the material used is as tough as use in tyres - it'll last.


The bellows themselves are simple enough to replace - I don't know about roadside but they can be replaced as easily as a shock absorber for example, or a coil spring. (Jack the vehicle up an go to work).
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Old 3rd May 2011, 19:57   #9
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Default Re: Air vs Leaf suspension for Buses

Air bellows often last for 1lakh KMS.
For a replacement it needs a trained mechanic and definitely not advisable in road side.
If not fitted properly it may cause some height difference between the two fitted bellows.
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Old 3rd May 2011, 20:14   #10
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Default Re: Air vs Leaf suspension for Buses

Quote:
Originally Posted by Ashley2 View Post
Air bellows often last for 1lakh KMS.
For a replacement it needs a trained mechanic and definitely not advisable in road side.
If not fitted properly it may cause some height difference between the two fitted bellows.

I think he was asking about emergency situations (bellow blown, got to move the vehicle back - can you do it with some emergency repair).

He talked about a trained mechanic himself.
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Old 3rd May 2011, 22:43   #11
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Default Re: Air vs Leaf suspension for Buses

air bellows can be changed by any mechanic with basic tools and of course the mechanic should know how to ? besides that nothing to worry. also the air suspension kits are made such that incase of bellow puncture, you can lock that side, and ride to the destination. the locked side would be rigid, thats all.
daily checks and cleaning with water, will make the air bellows to work longer. this daily cleaning will show you any cracks or exterior damage, which can make you reduce the risk of puncture on the highway runs.
average air bellows life is approx. 1 lakh kms or 3 years. but my buses have run a full 2 lakh kms within 5 years with not a single fault in the air suspension. yearly changing of the bushes, periodic air valve checks are the maintenance needed often - once every 15-20 days.
best regards.
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Old 5th May 2011, 00:27   #12
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Default Re: Air vs Leaf suspension for Buses

Thanks for all your responses on the air bellows, this gives me even more confidence to go ahead with air suspension!
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Old 5th May 2011, 12:52   #13
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Default Re: Air vs Leaf suspension for Buses

Just linking to something related. For those who want to see these bellows up close :

(Component & Equipment Manufacturers at Auto Expo 2010)


More pics & details here (Component & Equipment Manufacturers at Auto Expo 2010)

cya
R
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Old 7th May 2011, 16:40   #14
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Default Re: Air vs Leaf suspension for Buses

I think leaf-spring suspension was made for Trucks. The Busses were always meant to have air-suspension.

A Bus with a leaf-spring suspension is nothing more than a truck with seats. Like the FORD ENDEAVOUR
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Old 7th May 2011, 16:54   #15
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Default Re: Air vs Leaf suspension for Buses

Quote:
Originally Posted by TheARUN View Post
I think leaf-spring suspension was made for Trucks. The Busses were always meant to have air-suspension.

A Bus with a leaf-spring suspension is nothing more than a truck with seats. Like the FORD ENDEAVOUR

well your post would make a lot of sense if air-suspension was invented/productised before leaf-springs. Unfortunately leaf springs have been around for centuries.


also leaf springs are much more robust than most other systems - though they compromise ride comfort. therefore trucks use them.
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