Using Air Bags to lift ramps

I have never used air bags before (the lifting type), but I think my latest project would benefit from them.
I have a "chassis dyno" in the shop, and it uses two ramps that you
drive the car up, then once the drive wheels are on the dyno rollers, I lift the ramps up with floor jacks to be level, and place stands under the ramps. Once the car is in place, only the non-drive wheels are on the ramp, so the lifting load is easily manageble with a floor jack on each ramp, lifting them each evenly. I would estimate the max load the air bags would EVER see to be 2500 lbs.
The problem with using the floor jacks is... quite simply it is clumbsy, and can be slow.
Here are my obsticles. The ground clearance is about 4" where the lifting must occur, and the distance it must lift is about 14" total, or 10 inches from the lift point.
As far as I know, this would eliminate any hydraulic bottle type jack because of the stroke required.
I googled "lifting air bags" and have contacted a couple of companys for some initial pricing info, but I suspect it will be expensive. I can live with the jacks if it is priced out of my league, but I need to investigate this fully before I abandon it.
So, does anyone out there have some positive advise, of HELPFUL pointers of things I might be overlooking? Maybe some resonably priced vendors, or applications that may work also?
Thanks for the interest!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jul 27, 12:30 pm, snipped-for-privacy@hotmail.com wrote:

Sounds like you need a custom assembly that would be just like a floor jack, except maybe the bottle could be vertical. The jack bottle could go near the high end of the ramp, and a linkage could extend out to the 4-inch clearance part of the ramp.
Single controller/pump, some hydraulic line, and you'll have a very slick professional-looking setup.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The ground clearance is about 4" where the

Could you adapt a pair of scissor jacks? The type that are OEM on GM pickups come to mind. Maybe tie a pair together with a common shaft and motor drive it?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hunter front-end alignment racks have used air bags for years. Go to a chassis/tire shop and look one over.
-Carl
--
The future isn't what it used to be.



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Another thing you might look into is hooking in a hydraulic cylinder on each ramp to lift them at the same time. They make manual hand pumps if you don't want to use an electrical one. I believe that the mobile dynos (i.e. Mustang?) use this kind of system, but with a rather extensive system to life more than the ramps.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Perhaps some type of linkage that would allow you to use a hydraulic or pneumatic cylinder laid horizontally or at an angle.
Shawn
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com wrote:

Air bags from a semi suspension will go nearly to 4", without the regular gear that goes with them. There's also smaller airbags for cab suspension, I believe they'd do what you need. And there's in-between bags that are intended as helper springs for medium duty trucks, a friend of mine put a set on a truck for about $250. If you want the name of those, I'll give him a call.
John
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@hotmail.com wrote:

Well, you could always chew a hole in the floor to mount hydraulic jacks or cylinders in. You could also just buy a pair of air-over hydraulic floor jacks, which should be faster and able to work in tandem, and might even be able to be set in place semi-permanently. I don't know if there are any short/small bottle jacks that make use of telescoping cylinders - seems unlikely.
--
Cats, coffee, chocolate...vices to live by

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 27 Jul 2007 09:30:40 -0700, snipped-for-privacy@hotmail.com wrote:

http://www.firestoneindustrial.com/north_america/industrial/product_description/airstroke_actuators.shtml
--
Ned Simmons

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.