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 Post subject: "Titan" air jack
PostPosted: December 22, 2010, 4:25 pm 
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Yo!
In another thread, we got into a discussion of air jacks for a Locost. I was sorta half-heartedly researching these things, and came upon this:
http://www.airjackusa.com/
I remember reading about these things somewhere, years ago. My question is, does anybody in the group have any "real" experience with such a device? As in, have you actually used it, or been present when one was used? If so, do they work? Seems like a cool way to lift a low-slung car, a race car, or any other car for that matter.

Or, more in line with the original thread, does anybody know a source for cheap pneumatic cylinders that could be attached to the frame to lift the car, like the ALMS guys do?

Any input, anybody?

Peace, Love and Air Jacks-
JDK

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 Post subject: Re: "Titan" air jack
PostPosted: December 22, 2010, 5:56 pm 
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Proper air jacks aren't cheap and you have to have a big nitrogen cylinder with you at the track to hook the car too.
Are you planning on running races that will require the speed of lifting that air jacks offer or you just want something that lifts the car?

Moti

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 Post subject: Re: "Titan" air jack
PostPosted: December 22, 2010, 10:17 pm 
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Those Titan exhaust powered airbag jacks are cool, look like a must have in a 4 wheeler or possibly even a rally car.

Cheap disposable air cylinders abound at industrial supply joints. Do a search for "Bimba", they're one of the common brands. You'll want one-way, spring-retract, they'll be available with a threaded rod so you can screw on some UHMW lifting pads.

Ballpark lifting capacity can be figured out using:

Lifting Capacity = (PSI) πr²

You'll want to give yourself some safety factor (1.5x - 2x is a good place to start).

If you're running a nitrogen or carbon dioxide cylinder with a regulator you can run 200+ psi and get away with little cylinders, if you're running 100ish psi shop pressure you'll need bigger cylinders which will get heavy and expensive.

Figure your "heavy" corners will be about 600lbs, you'd need a 2.75" bore cylinder for shop air, 2" bore for 200psi.

t


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 Post subject: Re: "Titan" air jack
PostPosted: December 22, 2010, 10:36 pm 
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Cool topic, i was planning the same thing, just hadn't got to the research point yet... so nitrogen and co2? Didn't expect that...


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 Post subject: Re: "Titan" air jack
PostPosted: December 22, 2010, 11:48 pm 
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Blackbird wrote:
Proper air jacks aren't cheap and you have to have a big nitrogen cylinder with you at the track to hook the car too. Are you planning on running races that will require the speed of lifting that air jacks offer or you just want something that lifts the car?


Hi Moti-
Not planning to do any "NASCAR Style" pit stops, just kinda thinking that if I have a front splitter, side pods (likely fiberglass) and a rear diffuser, that doesn't leave any obvious places to slide a jack under the car. Plus, the car is going to be kinda low to the ground, making it more difficult to get a jack under it.

I was thinking that a fairly flat "air cylinder" (as Ted put it) could slide under the low clearance, be easy to push under the sidepods to the frame, then open a valve and raise the car. As you point out, the problem is having either a compressor or a big bottle for supply.

The "Titan" style air jack might work, but it looks like it's kinda slow, like 2 to 3 minutes to raise the car using exhaust. (Might be faster with compressed gas, but that leads to the supply problems like the other air jack.

I might look into the "Titan" style a bit more. Found one earlier tonight called "Bush Ranger" or something, looked very similar, bigger, and more expensive. It's more to lift your stuck 4X4 out of the sand as opposed to changing tires on your Honda. Overkill for a Locost.

I also will look into the leads that Ted gave us, air cylinders and such. Perhaps there's another method in there somewhere.

Hmmmmm..... Mostly just thinking out loud. Stay tuned!
JDK

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 12:54 am 
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A friend of mine is building a desert racer on a tight budget but does need the ability to lift the car quickly if he pops a tire.
The idea that he came up with was brilliant - 3 acme threaded rods mounted inside couplers that are welded to the car where you would mount air jacks, with a 1/2" drive socket welded on top of each threaded rod (meaning you need top access).
So, when comes the time to lift the car, you can run around it with a good cordless 1/2" impact gun and quickly lift the entire car or the corner that you need to work on.
It's not super cheap, but it is a nice solution on a budget.

Moti

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 12:55 am 
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Can't you just use your air compressor rather than nitrogen or C02 bottles?

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 12:59 am 
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carguy123 wrote:
Can't you just use your air compressor rather than nitrogen or C02 bottles?

Sure, you just need to take your air compressor to the track every time..

Moti

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 1:05 am 
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A lot of us do, plus there are usually more than a few around.

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 2:09 am 
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It also depends on the diameter of the pistons and the weight each is lifting. A 90 psi air compressor isn't going to do the job if it's a 1" diameter piston with 500 lbs on it. OTOH A 3000 psi nitrogen tank can launch the car to the moon without a regulator...

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 2:54 am 
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carguy123 wrote:
A lot of us do, plus there are usually more than a few around.

If you're talking about little tire compressor that plugs to your cig lighter it ain't going to cut it.
If you're taking a real compressor to the track with you, you need power to run it, so you have to take a generator which takes more space in your tow vehicle and adds more weight in addition to the weight and space that the compressor itself takes.
Or an inverter box that will force you to run your tow vehicle's engine every time you need to lift your car.

I'd rather drag around a nitrogen bottle with me at this point, even a smallish bottle would lift the car a bunch of times (in a second) and I'll have nitrogen for the tires too 8)

Moti

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 3:25 am 
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They do sell those Bimba air cylinders cheap on Ebay. Less then $50 for something like 2" x 8" stroke.

Gonzo maybe you put some jack points into your build. If your going to have pontoons (really?) then make a strong support in the middle that a standard low profile HF aluminum floor jack would fit. Or bring it into the pits up on two wheels and have a nimble crew member with a jack stand ready when you stop. If you have the nimble crew member you could just use a can of ether and those big inflatable bags you gave a pointer to.

They have plumbed air to all the garages here at our local track, thanks to NASCAR...

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 8:57 am 
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You could also weld some rally style jacking points in which would let you use an old VW/Porsche Bilstein jack. The jacks slide easily to the initial height and are fairly quick in use.

t

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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 9:25 am 
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Hey Ted-
Those look very much like the jack points for an MG Midget, and the jack is very much like the OEM jack for Midgets and MGB's. (Difference is the MG jack was a threaded "screw" type, not a ratchet.) On the MGB, the jack point was a tube welded under the door sill. They were notorious for rusting, and taking the sill with 'em.

Marcus-
I'd considered building jack points on each side, basically extensions of a cross rail of the lower frame, with a triangulation piece up to the upper frame rail. But, since I'm still kinda thinking the sidepods would be removeable, that'd leave the jack point stickin' out there when the 'pods were off the car. Hmmm... maybe just make the pods permanent...

But, what intrigues me are the air cylinders that Ted mentioned. I looked on Ebay and they're for sale all over the place, varying bore and stroke dimensions and I don't know what size I'd need. With a car 3 inches off the ground with about 3 inches of droop, seems like I'd need more than 6 inches of travel on the cylinder. Right??? The bore would only be a matter of having the rod big/strong enough to hold the weight of the car. Right??? (Y'all chime in here, iffen ya know!) The combination of a nitrogen cylinder for tires and jacks is interesting, too. (Thanks for that one, Moti!) Again, seems like a big cylinder with high pressure (1000 psi?) would fill tires and lift cars for a while. Airgas's website didn't have prices, still checking...

And, I haven't seen a weight listed for these "Bimba" (or equivalent) cylinders that would get mounted on the car. I guess with a Ford V8 and my fat arse in it, I shouldn't worry, but still....

Peace, Love and Pneumatics!
JDK

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Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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 Post subject: Re: "Titan" air jack
PostPosted: December 23, 2010, 9:51 am 
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The Bimba's are fairly light, aluminum bodied, aluminum endcaps, maybe throw some droop limiters on the car (old seatbelts?) so you don't have to use long cylinders.

Yeah, Mini's had those square peg jacking points in the sills as well -- the BMC jack (joke?) was awful though, the "Jam trousers" of jacks :)

t


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