Airlift has a new 7" airbag system for pickup trucks with a 7500 lb load rating at 100 psi. I wonder if these would have more or less bounce than the smaller 5000 lb rated bags available. I'm not affiliated with this company and generally steer people away from bags under a truck camper, but others may be interested in this new LoadLifter 7500 XL.

Thought number one is I hope they have upgraded the bracketry, since the 5000 brackets break with some regularity.Thought number two: how much "bounce" is primarily related to spring rate. The spring rate of an air spring is proportional only to the height of the spring, and independent of the diameter. That may seem non-intuitive, but it is true. So unless they are taller than their 5000 product, the spring rate will be the same, and the "bounce" will be the same.

No more mistaking air bag for air spring. First one is spring the 2nd one bag Different construction, different principals, different characteristics. I was driving F450 with 5000 lb air bags and even with 10,000 lb payload, I not always inflate them fully. Meaning you might have no use for bags that will lift the bed higher than normal level.

HMS Beagle wrote:The spring rate of an air spring is proportional only to the height of the spring, and independent of the diameter. That may seem non-intuitive, but it is true. So unless they are taller than their 5000 product, the spring rate will be the same, and the "bounce" will be the same.7500lb. bags at the same PSI as the 5000lb. bags are going to have a higher spring rate. To get the same spring rate in a larger diameter bag, you won't need as much pressure, which will lower the spring frequency, FWIW.Personally, I've never noticed the dreaded bounce with airbags and good shocks.

I have had Air Lift Systems 5000 lb airbags on every one of my 2500 and 3500 GM pickups since 1993 both for my business and my personal trucks and NEVER had any bounce from any of them. That's what good truly adjustable to the load shocks are for but so many cheap out and buy set load dampening shocks and it's a head scratcher! Like one size does NOT fit all nor all conditions! Good adjustable shocks dampen to almost totally eliminate any bouncing. I have no financial interest in Air Lift at all other than being a very happy well satisfied long time customer. All truck brands suspension designs are not the same which means different results with using the very same airbags. I have yet to have or see an Air Lift System airbag bracket fail or break and not even on our first which was later sold to an asparagus farmer neighbor of property we own and at over 440,000 miles and 24 years of being on the truck, the bags still are working fine but he sure has beat up the body of the truck and the bed the last 3-4 years. He's run into it with his front loader bucket and dropped gobs of very heavy stuff on the bed. We see the 1993 truck many times a year and are good friends with the farmer/owner. He has a newer truck for personal use now and just uses the 1993 for beat the heck out of it things. O'well, it's his truck and has been for 12 years now so why should I really care what he does with it? Basically, I wouldn't have a truck carrying a heavy load like a big TC or a heavy 5th wheel pin weight without having airbags. Air Lift System air bags properly inflated for sure and I'm all for the 7500 lb bags as with 5000 lbs on'em, that would only be 2/3 of their capacity! Smart people won't use a boy to do a mans job!

Tom_Anderson wrote:HMS Beagle wrote:The spring rate of an air spring is proportional only to the height of the spring, and independent of the diameter. That may seem non-intuitive, but it is true. So unless they are taller than their 5000 product, the spring rate will be the same, and the "bounce" will be the same.7500lb. bags at the same PSI as the 5000lb. bags are going to have a higher spring rate. To get the same spring rate in a larger diameter bag, you won't need as much pressure, which will lower the spring frequency, FWIW.Personally, I've never noticed the dreaded bounce with airbags and good shocks.It will in fact lower the spring rate to exactly that of the smaller bag bag. To be clearer, I should have said "supporting a given load" spring rate is proportional to installed airbag height, and independent of diameter. The force is pressure times area, but the rate at a given load is simply the rate of change of volume - and that is proportional only to the installed height. The spring frequency is a function of the rate and supported load - this will also be identical between the two in a given installation. The only way to soften the rate of an air spring supporting a given load, is to make it taller.

7500 lb Rated Bags | Good Sam Community

Tom_Anderson
Explorer
Dec 11, 2016
HMS Beagle wrote:

The spring rate of an air spring is proportional only to the height of the spring, and independent of the diameter. That may seem non-intuitive, but it is true. So unless they are taller than their 5000 product, the spring rate will be the same, and the "bounce" will be the same.

7500lb. bags at the same PSI as the 5000lb. bags are going to have a higher spring rate. To get the same spring rate in a larger diameter bag, you won't need as much pressure, which will lower the spring frequency, FWIW.

Personally, I've never noticed the dreaded bounce with airbags and good shocks.
Kayteg1
Explorer II
Dec 10, 2016
No more mistaking air bag for air spring.
First one is spring

the 2nd one bag

Different construction, different principals, different characteristics.
I was driving F450 with 5000 lb air bags and even with 10,000 lb payload, I not always inflate them fully.
Meaning you might have no use for bags that will lift the bed higher than normal level.
HMS_Beagle
Explorer
Dec 10, 2016
Thought number one is I hope they have upgraded the bracketry, since the 5000 brackets break with some regularity.

Thought number two: how much "bounce" is primarily related to spring rate. The spring rate of an air spring is proportional only to the height of the spring, and independent of the diameter. That may seem non-intuitive, but it is true. So unless they are taller than their 5000 product, the spring rate will be the same, and the "bounce" will be the same.

Forum Discussion

7500 lb Rated Bags

About Travel Trailer Group

Related Content

7500 Onan

7500 cummins onan

Onan 7500 removal question

Onan 7500 stator replacment

air bags