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post #1 of (permalink) Old 01-06-2001, 12:01 PM Thread Starter
 
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help a Suzuki-guy? - airtank-mobile-winchbumper

Hi folks,

here's the story...

I have a Samurai (which isn't really that important now ;O) and i plan to do an "air-tank and mobile-winch bumper" (tm)...

The idea is to use a 3x3" square tube with ,12 wall...aprox. 60" long (total 540 ci) that also serves as an airtank.

The clue is to put some 2" receivers in there (front and rear) and to mount the winch on a plate w/ 2 receivers... so i can

a) leave the winch at home (for shopping)
b) leave the winch inside the truck (gen. offroad - excellent attack and dep. angles)
c) put the winch in front or in the back (only if its REALLY needed)


i'll post 2 piccies...

can you help me out with the air-tank issue... does it make sense (i just want to inflate my 31" after the trail, dont want to run tools, etc...)

my idea (i am NO expert) is to put 2 air valves (same as on wheels) on either side and fill the bumper before wheeling at a gas station. Would this work?

any input welcome (and the Suzuki-jokes are on me ;o)

thanks
alfred





'95 Stofttop, K&N, Snorkel, 4,5" SPOA, 31" BFG MT, 4,16gears, W5000 winch, skidplate, rear Rancho 9000 - other than that its bone-stock
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post #2 of (permalink) Old 01-06-2001, 12:04 PM Thread Starter
 
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

2nd pic



'95 Stofttop, K&N, Snorkel, 4,5" SPOA, 31" BFG MT, 4,16gears, W5000 winch, skidplate, rear Rancho 9000 - other than that its bone-stock
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post #3 of (permalink) Old 01-06-2001, 07:10 PM
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

Hey there, nice Zuki! Still running the stock shackles, surprised you haven't ripped them off by now. How do the RS9000's work on such a light rig?

I did some quick math, and:

your bumper will have a capacity of 0.3125 cubic feet.

Your tires each have a capacity of 1.83 cubic feet (assuming "true" 31's)

So, to air up from, say 5 pounds to 20 pounds (I've wheeled a Zuki before, they need a LOT less air in the tires). So the delta is 15 psi.

Assuming constant temperature, we'll use Boyle's Law to find the pressure needed in the tank to pump up the tires back to 20 psi.

Pf/P = V/Vf

where Vf and V are the final and initial volumes, and Pf and P are the final and initial pressures

So, doing some quick math, it looks like:

15 psi/"X" = 0.3125 cubic feet/7.32 cubic feet (all 4 tires)

Solving for "X", we get (15*7.32)/0.3125, so "X" = 351.4 psi.

So you'd need approximately 351 psi in your bumper to air all 4 tires back up. I don't think you're going to get that from a garage air compressor. The only thing you can do is

1) put in a larger bumper

2) don't air up/down your tires as much

Otherwise it sounds great. I would also add a few drains, one at either end, to drain any condensation out of the bumper. With what I've posted here, you should be able to play around with bumper sizes and pressures. If you need a hand, let me know, glad to help out.

If we back calculate using 120 psi from the standard shop compressor, I find a volume of 0.915 cubic feet is needed, and with a width of 60" (5 feet), the bumper would need to be 5" x 5.25" to work, or be 5.8" in diameter if you used a round tube.

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post #4 of (permalink) Old 01-06-2001, 08:02 PM
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

Wow. I feel smarter. I knew that Boyle's law was what you needed, but couldn't remember the formula.

Thanks for the learn'.




Jason

----------------
[]llll[] '90 YJ, NV4500, XD9000i, 35" MT/R, Snorkle, 4.5" RE lift, Tera Revolvers, etc. etc.
post #5 of (permalink) Old 01-06-2001, 08:29 PM
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

[img]/wwwthreads_images/icons/smile.gif[/img] First I'm going to stipulate that Jeep"N"'s concept is accurate and that his math is flawless. That having been said I have to once again remind the posters that MECHANICAL TUBING is not NECESSARILY pressure worthy. The seams on mechanical tubing are made for stresses from bending and other mechanical loads, but were never intended for any kind of separating forces due to internal pressurization, and the seaming process therefore does not take that into account. You could get lucky and have no problem, but on the other hand it could also take your life. An Arizona dairyman used one of those army surplus round buoys as a pressure tank for their new, hydro-pneumatic water system and as the pressure built for the very first time a weld let go and flying steel killed the dairyman's son. Those buoys were welded to just float, and that is probably where the novice welders in the shipyards started out learning to weld. After all if a buoy sinks it's no big deal. If a ship comes apart, or your tube fails, that's something else.[img]/wwwthreads_images/icons/tongue.gif[/img] Going further with this I might take this time to point out that in the formula for cubic inches (Bore X Bore X.7854 X Length) the significant figure is the bore, or the inside measurement of a given shape in the formula (L X W X H). You can readily see that a tiny increase in diameter or cross-section has a HUGE effect on volume. So if you have a place to put it, a weenie-shaped truck air tank of even modest diameter will carry the air you need, and do it safely.[img]/wwwthreads_images/icons/smile.gif[/img]

CJDave
Quadra-Tracs modified While-U-Wait by the crack moonguy[img]/wwwthreads_images/icons/wink.gif[/img] Quadra-Trac Team.[img]/wwwthreads_images/icons/tongue.gif[/img][img]/wwwthreads_images/icons/smile.gif[/img]
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post #6 of (permalink) Old 01-06-2001, 09:43 PM Thread Starter
 
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

hmmm....

first of all ... thanks for the math and information...

i guess i will put the air-tank idea a little bit on the backburner...

Given the fact that the two receivers will "receive" quite some stress winching, i'd rather not have them pressurized...

i'd like the convenience, but it seems that the "price" aint right

thanks for pointing this out to me

Alfred

'95 Stofttop, K&N, Snorkel, 4,5" SPOA, 31" BFG MT, 4,16gears, W5000 winch, skidplate, rear Rancho 9000 - other than that its bone-stock
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post #7 of (permalink) Old 01-06-2001, 10:18 PM
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Re: help a Suzuki-guy? - airtank-mobile-winchbumper

Dave is right, personally I wouldn't use the bumper as a receiver anyway.

Look into a place that services big trucks and/or forklifts. They have access to air tanks used on both vehicles, with the forklift ones being about right for the Zuki's size. They could even be mounted underneath, out of the way, on both sides of the rear driveshaft and plumbed together. They're fairly cheap as well. I would put a guard over them to protect them from wheeling, but it'd be easy to make. The tanks are also designed for holding compressed air, so no worries there.

I like the winch arrangement you had for the front, but how would you attach the rear? I have had the rear bumper off a Zuki, helped Max (<font color=blue>mxnhid</font color=blue>) build his cage, and there isn't much back there to attach to.

JEEPN
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'81 CJ-8 Scrambled!
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