Air Jack

[Ron B]

Ah, when you originally said a 5lb tank, I assumed you meant it was a CO2 type tank, which is quite a bit less than a gallon in volume, but more like 2000psi...

A 5lb (2.5 litre) tank at 200psi (14kg/sq.cm) can provide only 32 litres of air at atmospheric pressure, so it couldn't even inflate the bag (must be well over 100 litres) to atmospheric in the first place, let alone pressurise it enough to lift half your vehicle (2000kg?)!

With CO2 at 2000psi, it could do so easily, since at that pressure, a 2.5L tank can provide around 1200 litres of C02. And of course, so could your 5gal (20 litre) 200psi as it can provide around 260 litres of air.

The speed with which it inflates the bag it is presumably just a function of the pipes and fittings you are using - are they standard? And when did you start measuring the time? (i.e. bag completely empty? Or inflated, but not under any load? Or weight already taken?)

I've used air jacks quite a bit, but always using the exaust, which can be tricky if the exhaust is inaccessible or leaking. It is also a dirty job when the vehicle is a diesel! So I am interested in trying it with compressed air instead - seems to me one can control the whole operation better with an air hose, than when one is trying to hold the end of the pipe over the exhaust.

holding the hose over the pipe was, uh, not fun -- the hissing and whistling nearly deafened me (not to mention torturing every dog in the 'hood) a the bag barely inflated. It just didn't work with my pipe. The dirty nature of diesel is a good point you make so maybe I'm glad it doesn't work. The compressor fitting has a lever on it so the inflation can be easily -- unfortunatley the only way to deflate is to unscrew the whole hose which again risks deafness.

As far as the bag inflating from my tank...it happened exactly as I explained it. Bag freshly out of the box (zero air in it), unrolled it under rocker panel, plugged it into my ob 5 gal tank (filled to 200 psi with ob viar 480c), turn knob, rear tire of 7500 lb truck 4" off ground (and front tire also nearly off) in under 10 seconds. After about a minute or so of recharging the tank to 90-ish psi, another 3 or 4 second blast of air lifted it another 1.5-ish inches to the 5.5 inches pictured. I am using standard air fittings (in the picture you can see my tank above the rear tire as well as a 6x6 block of wood on the ground next to the tire for reference) and didn't have regulator in-line. I'm sure that would have slowed it down a bit.

rb

 

[Ron B]

I've got an airjack that I've had for yonks but have never used. It's only got a fitting for an exhaust. Do you think it's feasible to convert it for use with a compressor?

I bought my fitting with the bag -- I'm sure the manufacturer of yours has that accessory. It was about $30 for mine, glad I got it as mine won't work with my exhaust tip.

rb

 

[michaelgroves]

Bag freshly out of the box (zero air in it), unrolled it under rocker panel, plugged it into my ob 5 gal tank (filled to 200 psi with ob viar 480c), turn knob, rear tire of 7500 lb truck 4" off ground (and front tire also nearly off) in under 10 seconds. After about a minute or so of recharging the tank to 90-ish psi, another 3 or 4 second blast of air lifted it another 1.5-ish inches to the 5.5 inches pictured.

I've just been looking at the specs of the Titan - assuming you have the 3-ton version, it's got a fully inflated volume of 183 litres. To be able to lift 3,000kg, this air must be at a pressure of 1kg/sq.cm (the jack's base has a radius of 30cm, so its footprint is around 3,000sq.cm).

1kg/sq.cm = 1 Bar =1 atmosphere, so we need 183 litres to inflate the bag, and another 183 litres to pressurise it. So at the extreme, you need 360 litres to lift a full 3 tons to the maximum height. Your 20 litre tank is at 14 Bar (200psi), so you have 280 litres. I guess you're not lifting a full 3 tons, nor are you filling the bag completely (any idea how much lift there is still to go after the 5.5 inches?).

The reason I am trying to work it out, is to see what sort of tank capacity makes using OBA instead of exhaust a viable option. Without a big holding tank, none of the OBA compressors can provide the volume of air that an exhaust jack needs - they are high pressure, low volume compressors. I'd think 20L would be at the lower limit of what's required.

Anyone else have thoughts on /experience with this?

 

[Ron B]

I have the 4 ton version -- I think on the box it says the lifting capacity is about 4500 lbs. I may have been able to go a bit higher but the top of my truck was getting close to my garage door. The inflated bag is 30 inches tall and I had it up to 26 inches.

Here the web page incase you don't have it:
http://www.airjackusa.com

rb

 

[michaelgroves]

It's interesting that the two "versions" of the Titan jack seem to differ a bit in their specifications. Airjackusa, Northern Tool and Amazon all describe the 3-ton jack as having a lifting capacity of 3 tons, whereas the Streamlineimport site (with a different product code), describes the lifting capacity as 1.54 tons, suitable for a 3-ton vehicle. And Northern Tool quotes the same base dimensions for the 3-ton as Streamline quotes for the 4-ton.

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200335091_200335091
http://www.streamlineimport.com/Order.htm
http://www.airjackusa.com/features.htm

But Airjackusa and Streamlineimport agree that the maximum pressure is 0.7 bar. So for a jack with a base diameter of 60cm, the area is 3000sq.cm, and at a pressure of 0.7bar (0.7kg/sq.cm), that yields a lifting capacity of 2100kg. Which gels with Streamline's specifications for their nominal 4-ton model.

That changes my calculation somewhat, because to lift 2000kg (the actual maximum) obviously requires less air than to lift 3000kg. Perhaps oddly enough, the diameter of the jack makes no significant difference to the amount of air needed to lift any given load, once the bag is filled to atmospheric pressure. Basically, from that point on, you need 10 litres of "free" (atmospheric pressure) air per ton per centimetre of inflation height, regardless of the dimensions of the bag. Once you've stuffed the required amount of air in, a small air jack will be at high pressure and a big air jack will be at lower pressure, but both will lift the same load to the same height.

If you ever get the chance, Ron, it would be interesting to know how many times you can inflate (but not pressurise) a fully deflated bag from your full 5gal, 200psi air tank, with the compressor switched off. I'd estimate it will fill the bag about one and a half times?

 

[Spikepretorius]

It's interesting that the two "versions" of the Titan jack seem to differ a bit in their specifications. Airjackusa, Northern Tool and Amazon all describe the 3-ton jack as having a lifting capacity of 3 tons, whereas the Streamlineimport site (with a different product code), describes the lifting capacity as 1.54 tons, suitable for a 3-ton vehicle.

Is that not maybe just confusion between metric and imperial tons?

 

[michaelgroves]

Is that not maybe just confusion between metric and imperial tons?

I think it's a marketing thing - a way of making the jack capacity sound higher than it is. A metric ton is 1000kg, a long ton (UK) is 1016kg, and a short ton (USA) is 907kg, so they are all pretty close.

 

[Guinness44]

Whatever jack is used: DO NOT forget a backup when you pull a wheel. What worries me with the airjack is that they are shown on flat ground, on sand. Wondering if that jack rolls like a ball if not perfecly balanced, or someone jumps into the truck to look for a tool. If tires get poaked by Mesquite bushes, beyond repair, how would that do to the jack. (O.K. I am paranoid, but I lost a dear friend in a jacking accident).

 

[michaelgroves]

Whatever jack is used: DO NOT forget a backup when you pull a wheel. What worries me with the airjack is that they are shown on flat ground, on sand. Wondering if that jack rolls like a ball if not perfecly balanced, or someone jumps into the truck to look for a tool. If tires get poaked by Mesquite bushes, beyond repair, how would that do to the jack. (O.K. I am paranoid, but I lost a dear friend in a jacking accident).

:iagree:

They do tend to roll around. With regard to punctures, they are pretty hardy, but they can easily get holes from sharp stones or thorns, or jagged bits on the bottom of the car. In principle, they don't actually burst, even with a knife thrust into them at full pressure, but I wouldn't like to try that!

 

[jfarsang]

Bump :coffeedrink:

Any comparisons between the ARB and Titan ?

Also, you guys that are using them...

out in the field... how are they so far ?

 

[cnskate]

Are you air jack owners just leaving the Hi-lift at home now? I'd like to lose the weight of the Hi-lift. Using something that dangerous in the middle of nowhere kind of seems like a bad idea.

 

[HenryJ]

Are you air jack owners just leaving the Hi-lift at home now? I'd like to lose the weight of the Hi-lift. Using something that dangerous in the middle of nowhere kind of seems like a bad idea.

My high-lift has been shop bound since the purchase. I have journeyed out many times, but just toss in the airjack. I have not needed either jack and I have a winch that has been used, so I may not be the best test.

 

[Gone2Baja]

I have a 3 ton titan with the co2 fitting, It works great! With my powertank It lifts both tires in about 15 seconds, my hi-llift just sits in the garage. The hi-lift is a great tool but it's heavy and could be dangeres.

 

[Tony LEE]

Whatever jack is used: DO NOT forget a backup when you pull a wheel. What worries me with the airjack is that they are shown on flat ground, on sand. Wondering if that jack rolls like a ball if not perfecly balanced, or someone jumps into the truck to look for a tool. If tires get poaked by Mesquite bushes, beyond repair, how would that do to the jack. (O.K. I am paranoid, but I lost a dear friend in a jacking accident).

I would never use it to change a tyre unless the vehicle was properly blocked. Have used it several times to lift a vehicle out of deep thick mud and sand enough to pack under the wheels .

Yes, they will roll like a ball and this is one of the uses for it - jack up under the rear centre of the vehicle and push it sideways to get the wheels onto firmer ground. You can also angle the bag to make sure it pushes in the right direction

 

[Dave Bennett]

Any update on the comparo???