Air Bags - What Do They Do?

[richf28]

I too have airbags on my half ton. I can tell a difference in the amount of sway since I installed them. I have tried different presdsures and have actually been able to see the difference in handling with even a 10 lb change in pressure.

[azlee56]

this is interesting. I read you all and then ask the bf (he hauled for oil companies) what a "payload" meant because when I talked to truck drivers I thought it meant something else and the bf assumed you all meant the gross weight on axles. For the life of me I am not getting this stuff. I sent my weights to one of you in a private message but never heard back but I am a little timid putting it out there for all to mull over. BF says we are good and so does all the friends, but I get nervous on stuff.

Keep up this debate, maybe all this will sink in my head yet!!!

[azlee56]

ps. I am really impressed what the air bags did on our truck, but man if you aren't towing it makes a ride stiff.

[SAD]

Originally Posted by azlee56

...I sent my weights to one of you in a private message but never heard back but I am a little timid putting it out there for all to mull over....

A little timid? It's not like it's your social security number and date of birth.. If you've got questions about your weights, post 'em up!

Originally Posted by azlee56

ps. I am really impressed what the air bags did on our truck, but man if you aren't towing it makes a ride stiff.

Deflate them. You don't need lots of psi in them when not towing or hauling. Some do have a minimum psi, like around 10psi, but that shouldn't make the ride very stiff.

[rhagfo]

Originally Posted by azlee56

this is interesting. I read you all and then ask the bf (he hauled for oil companies) what a "payload" meant because when I talked to truck drivers I thought it meant something else and the bf assumed you all meant the gross weight on axles. For the life of me I am not getting this stuff. I sent my weights to one of you in a private message but never heard back but I am a little timid putting it out there for all to mull over. BF says we are good and so does all the friends, but I get nervous on stuff.

Keep up this debate, maybe all this will sink in my head yet!!!

I have posted my numbers in a couple of threads, I run about 900# over GVWR but well under GAWR, so don't be bashfull

[azlee56]

I leave the airbags for him to mess with, so he knows what is going on with them at all times. Right now they are aired up because we just came back from a trip. Glad he didn't take the air out because I went and got some bricks that is super heavy. We keep about 7lbs in it when we aren't pulling (I think is what he said).

Ok, here it goes.....now if you will be so kind and tell me how you all get from these numbers what is safe and what is ok but remember to stop in time.

2008 3500RL Montana
shipping weight 11920
carrying cap 3560
hitch 1980

Truck ford 2000 250:
7.3l 3.73 tranny
gvwr: 8800
rear gawr: 6084
front gawr 4550
Towing package
drive 60mph - 65mph only and on flat land

[azlee56]

lol, I'd probably be more at ease pasting the other stuff. I cringe when you all tell ppl not to pull with their vehicles and they just spent a wad of money on the trailer! That is the timid part....but that is ok, I can bear good or bad news. honest :-)

[jsmith948]

azlee 56

Relaaax! we are all friends here!

[rhagfo]

Originally Posted by azlee56

I leave the airbags for him to mess with, so he knows what is going on with them at all times. Right now they are aired up because we just came back from a trip. Glad he didn't take the air out because I went and got some bricks that is super heavy. We keep about 7lbs in it when we aren't pulling (I think is what he said).

Ok, here it goes.....now if you will be so kind and tell me how you all get from these numbers what is safe and what is ok but remember to stop in time.

2008 3500RL Montana
shipping weight 11920
carrying cap 3560
hitch 1980

Truck ford 2000 250:
7.3l 3.73 tranny
gvwr: 8800
rear gawr: 6084
front gawr 4550
Towing package
drive 60mph - 65mph only and on flat land

So if you were to scale it with the trailer attached, you are likely well over GVW, but likely within GAWR.
As stated earlier while 900# over GVW with three adults and two dogs, I still am over 1,000# under my rear GAWR.
As I stated in an earlier post I believe that the stock 235 HP rating of my 2001 Cummins has a lot to do wit the 8,800 GVW of my truck.

[azlee56]

been away to the mountains for a couple of days. I sighed a breath of relief, but what you all said that insurance companies can deny on the load stuff really sent me to thinking.


I do like the airbags (back on topic), I had gotten those bricks and so he could reach to unload them he let the air out of the bags (not all the air) and said it dropped the truck like 3 inches. I didn't realize those bricks were that heavy. Heavy yes, but not that heavy.

[TDF5G]

This what I found on the Air Lift website, They claim air bags do distribute weight and increase spring rate.

Air Lift air springs help:

Eliminate squat – Proper weight distribution to all tires eliminate squat and improves steering, braking and tire wear.

Improve headlight aim – Only level and stable vehicles provide safe and proper headlight aim which is critical for driving safely at night.

Increase handling and ride quality – Air Lift’s progressive spring rate absorbs road bumps and keeps your tires on the road for better handling.

Reduce bottoming out – Air Lift air springs restore normal ride height, reducing suspension wear and eliminating bottoming out on road bumps.

Control sway & body roll – Air springs increase spring rate and vastly improve vehicle stability. When towing a trailer, the air springs maintain your vehicle’s height which reduces trailer sway. Less roll and sway means a safer and more comfortable ride. This is also critical for motor homes or pickups with slide-in campers. These types of vehicles have a high center of gravity and a large surface area, and are heavily impacted by strong winds.

Now this is me talking; If you raise the rear of a 4 wheeled vehicle (truck, car, van, bus, motorhome, tractor, lawn mower, atv, golf cart, kiddie car, etc,) by whatever means, such as a WDH, air bags, a jack, a crane, or laying under the bumper and bench pressing it yourself, it seems to me that you will lower the front of the vehicle. Wouldn't that shift weight from the rear wheels to the front wheels?

[SteveC7010]

Raising the rear end with air bags does not change the amount of weight on that axle. It also does not change the weight on the front axle. It only levels out the vehicle.

[rhagfo]

Originally Posted by mrxlh

I have had air bags on my trucks for 5 years now. You are incorrect.

There is no difference between a WDH and air bags, the only thing you are physically changing with WDH and air bags is the height between the axle and frame. Thus leveling the vehicle and trailer. Which no matter how this is achieved, you still transfer weight to the front of the vehicle and to the axles of the camper.

The statement above is totally wrong.
The spring arms in a WDH work much like lifting the handle on a wheel barrow, you are now sharing the weight that was on the legs, between the handles and front wheel.

The best demonstration of this I have ever seen was back in the late 60's when they installed a WDH on an Oldsmobile Tornado, then removed the rear wheels and the WDH held the rear of the car in the air.

If your assesment was correct, simply airing up my air bags would have not changed the tension on my WDH. However it did so much that the tension was not there at all, hence no longer the need to use them.


As far as your statement about air bags not increasing the capacity of the springs, that is dead wrong, so much that most newer semi trailers do not use springs at all any more and use strictly air bags.

Not increasing the springs, they don't increase the GAWR nor do they add to the weight the axle can carry.

The secondary reason for air ride suspension in class 8 trucks (primary is much better ride) is it is far easier to change ride height of individual axles to achieve correct axle weights than it is to slide axles and hitches around.

Originally Posted by Bob Landry

Steve is correct. Airbags do nothing more than raise the rear of the TV for asthetic appearance and to keep the rear from botoming out with heavy loads. They do nothing for weight distribution forward or to the rear. A trip to a Cat scale will verify this. Hitch your trailer and weigh the front axle with no WD, airbags deflated, then inflated. You are doing nothing to alter the weight on either axle, you're just making for a cushy ride.
As far as the big trucks, air suspension can lessen the rough ride for the contents in the trailer, but I fail to see how changing the height of the load shifts ant weight or has any effect of the load on the axles.

All air bags do is level and soften (smooth) the ride. They do NOT move weight around, nor do they change the GAWR of the truck.

[TDF5G]

OK, if airbags level out a vehicle, that would mean the rear is raised and the front is lowered. So how would that not move some weight from the rear axle to the front axle? Or are you saying the front is not lowered after raising the rear and the front stays at the same height as it was before?

[sagebel]

I use my air bags to level the truck once loaded +1" and then hook the trailer and set the WD bars. Keeps the headlights on the road and takes out any bounce/seasawing. It would be interesting to see if any weight is transfered front to rear with the bags inflated. If I have time I'll try it the next time I am at the scales.

[Jim W]

Originally Posted by TDF5G

OK, if airbags level out a vehicle, that would mean the rear is raised and the front is lowered. So how would that not move some weight from the rear axle to the front axle? Or are you saying the front is not lowered after raising the rear and the front stays at the same height as it was before?

You may need to do some physics to understand this correctly.
Remember Newton's third law: For every action, there is an equal and opposite re-action.
What this means is when towing a trailer there is the mass of the trailer (pin weight, tong weight) which is pushing down on the rear axle, springs, wheels and tires. The Air bags are supplying and equal and opposing force in the opposite direction to provide equilibrium with all components. The rear axle, springs, wheels and tires are still supporting the same mass of this trailer, but using air bags to help support this load. Since the springs are flattening out in support of the load that is being placed on them. Springs will collapse when loaded but will supply an equal force in the opposite direction. They are just compressing to support this load and this is why the vehicle will sag.
Make sense to you?
Jim W.

[Jay D]

I would think that some weight would move!!!! I work on a race car and with the car on the scales when ever you turn any of the 4 springs up or down (raise or lower the chassis) you could see on the scale the #'s (weight ) being moved to the opposite side. LF - RR and RF - LR or both rears would move weight to both fronts and same would go for the fronts. Does that make sense to all. Jay

[rhagfo]

Originally Posted by Jay D

I would think that some weight would move!!!! I work on a race car and with the car on the scales when ever you turn any of the 4 springs up or down (raise or lower the chassis) you could see on the scale the #'s (weight ) being moved to the opposite side. LF - RR and RF - LR or both rears would move weight to both fronts and same would go for the fronts. Does that make sense to all. Jay

If you are only changing one corner, then you will move weight as the diagonal wheels act as a pivot point, but if you raise both on either the same end or side you will not likely see any weight movement, unless you raise it several feet.

[Jay D]

No even a turn or two would so