SpudFiles

Well, I've been thinking of running over Sh!t with a car again...

But only in a good way this time. I was thinking of this product :
Air Bag Car Jack


I'm daydreaming of a thick wood ramp with two parts and a hinge shaped like a ramp.
The bag would go in the middle, filled with just enough air to inflate.(or 125PSI).
Then a pneumatic hose with a ball valve would be attached and an air tank.
The car driven on top and the ball valve closed.
Also, With two tanks and two valves the process would be repeated (over and over) for higher pressure.
Any thoughts? Thanks in advance.

BTW, I was searching for link and also found: This Better air-jack
EDIT: it lifts "4500 lb.s" on 100 PSI.
I'm Also thinking that might be useful and more sturdy. (or just parts of it because it's expensive). 8) EDIT: (Fixed the links).

Sorry bud,


The average car weighs around 3000pounds (I think?).

There is a weight bias so let's agree that 65 percent of the weight will be carried by the front tires. That works out to 1950 pounds total and 975 pounds on each front tire.

The contact patch (of the tire) is going to be "roughly" 8" x 6" or 56 in2.

That works out to a contact pressure of 17.4psi. Not worth the effort in my book.

Feel free to try it out, maybe I'm wrong.

Why does the lady in the pictures look like she herself has been inflated?

*ahem*

I think you'd be better off hooking up the flywheel from a normal compressor to your car tire by simple friction drive.

@Gippeto, By using a ramp I mentioned, both wheels or even the full weight of the car would be on top of the air bag.
The volume of air in it would be compressed into a small metal chamber, and the ball valve closed. Then valve on other side opened into a larger tank.
High pressure hose or pipe would be needed. (I forgot to mention).

Also I find it interesting because the 100-125psi volume needed to lift 4500lb.s or so...
If used to compress a smaller volume (rather than lift a car) it's sort of like the concept of converting amperage to voltage. Only it's High volume low pressure TO High pressure low volume.

This concept is interesing to me because it could use air pressure itself to achieve that. (Air jack)
But I've really just started thinking about the possibilities. 8)

EDIT:

jackssmirkingrevenge wrote:Why does the lady in the pictures look like she herself has been inflated?

*ahem*...

I forgot to mention woman in pic is NOT my GF (or relation). (That's mean though)

THUNDERLORD wrote:I forgot to mention woman in pic is NOT my GF (or relation). (That's mean though)

The thing is people trying to sell stuff normally associate it with beautiful people, I though it was either an advertiser with an ironic sense of humour, or simply trying to appeal to America's growing population of obese people who lack the stamina to operate a conventional jack.

jackssmirkingrevenge wrote:...
*ahem*

I think you'd be better off hooking up the flywheel from a normal compressor to your car tire by simple friction drive.

Something like that should have awesome filling speed.
I wonder how much pressure a standard compressor could handle putting out though. Also heat might be an issue at those speeds.

I was wondering about those air bag car jacks for a long time.
I was thinking of an air chamber I could stand on, then open a valve to fire a blow gun dart (from my blowgun) years ago.

Just a quick easy way to get compressed air.
Now I'm wondering about a kevlar bag that could be run over by trucks or tracked vehicles. Or the friction drive mentioned.
Or a 100psi input jack to compress a 4500lb. spring piston.
Thanks for the replies! 8)

THUNDERLORD wrote:I was wondering about those air bag car jacks for a long time.
I was thinking of an air chamber I could stand on, then open a valve to fire a blow gun dart (from my blowgun) years ago.)

I proposed something along the same in this thread as a suggestion of how Indiana Jones style dart traps could be made to work.

The car would only be able to compress the air in the bag to the same pressure that is in the tires, so it really isn't worth the trouble.

I think you would be a lot better off modifying an automotive A/C compressor to fill a compressed air tank if you have your heart set on a car-powered air compressor.

Seems like a lot less time and effort to just buy a bottle of 3000 psi nitrogen.

ive heard of people who have used a single cylinder of a v6 or v8 to be used as an air compressor
i believe what they did is put a fitting in the sparkplug hole

THUNDERLORD wrote:@Gippeto, By using a ramp I mentioned, both wheels or even the full weight of the car would be on top of the air bag.
The volume of air in it would be compressed into a small metal chamber, and the ball valve closed. Then valve on other side opened into a larger tank.
High pressure hose or pipe would be needed. (I forgot to mention).

Also I find it interesting because the 100-125psi volume needed to lift 4500lb.s or so...
If used to compress a smaller volume (rather than lift a car) it's sort of like the concept of converting amperage to voltage. Only it's High volume low pressure TO High pressure low volume.

This concept is interesing to me because it could use air pressure itself to achieve that. (Air jack)
But I've really just started thinking about the possibilities. 8)

EDIT:

jackssmirkingrevenge wrote:Why does the lady in the pictures look like she herself has been inflated?

*ahem*...

I forgot to mention woman in pic is NOT my GF (or relation). (That's mean though)

See: Hydraulics.

Yes I know hydraulics deals with fluids lol. Just use the same theories and adapt them to air. No need to reinvent the wheel

it doesn't make much sense... I think that gippetto explained it quite well

using a car engine to power an air compressor does make some sense but
what you proposed is just a very funny way to waste ones time


finally, there are several things that can be a source of pressure... D_hall has already mentioned one.... all of them have their advantages and disadvantages and it's up to you and your funds/skills/needs/whathever which one you choose... of course no one said that you can not build something completelly new but the idea you proposed here sucks in every possible way so find another one


(I don't mean to be rude I am trying to safe your time (and possibly money))

More replies
@JSR, Thanks for the links/info. Interesting reading in those! Off topic but one time Harrison Ford walked up the sidewalk in front of me and I thought, "Looks familiar OH, It's Han Solo No wait, Indiana Jones...Holy crap He's..." Another (true) story though. Besides, he never made spudguns I know of and on SF's you get to communicate with the celebrities *cOuGH*CoUgH*

@potatoflinger depends on how the weight of the car is configured over the chamber I suppose.

@D_HALL That leaves out the innovation besides, maybe 3000psi could be compressed further by utilizing vehicle weight pneumatically or hydraulic (course at some point it would become liquid(?)).

@marpat, I wonder if doing that car cylinder thing would yield a perfect mix for use in combustion/hybrid Hmmm...

@mobile chernobyl perhaps the wieght from a car could be better utilized or converted to pneumatic with a hydraulic link in between.

Pneumatic would be quicker than hydraulic for example I was looking at the second link in OP and thought that sure would be a useful tool for car thieves.(EDIT or Rescue personnel) They could hook it to regulated C02 slide it under car, pressurize to 100psi and roll the car away.

@POLAND_SPUD: Really a broad topic seems like. With lots of principles and concepts involved.
Everytime I've seen that air-bag type car jack I start to wonder about utilizing car weight since I usually have a car nearby as well.
Guess having 3000+ Lb.s of weight easily utilized and readily available is a "sucky" Idea 8)

EDIT: Regenerative source for air cars built in the wheels(?)

you don't need that much force to make a pressure amplifier.... if an air ram has a 3 cm piston working at 10 bar it means that there are x=(Pi * 1.5cm * 1.5cm * 10 kg) of force acting on it (that's 70.65 kg)

now use that 70.65 kg to push a stirrup pump that has 1 cm piston what pressure you can get with it ?

Hasn't anyone here ever watched The Red Green show?

But yeah, this won't work very well (outside of TV).
You could use one of the cylinders as a pump, but you'll need to cut off the fuel going to it first.