GaryInOz (Vic) replied:

Just a few random thoughts.....

Have you considered the possibility of using a 12 volt motor to drive the compressor? Something along the lines of a small winch motor?

It does seem pointless and very inefficient to go from 12 V to 240 V simply to turn a shaft to a compressor. The start up current on a typical 240 V motor is about 5 times its normal running current, and you would need to factor this in with your inverter choice. Sems like you are trying to spend big bucks to save yourself small bucks.

There are a selection of medium to larger 12V compressors available (one of whose name escapes me at the moment) which would seem to fill you needs. What you really need is a medium sized compressor connected to a 30-40 litre tank which gets filled as you are driving, rather than trying to generate large quantities of air at the time of airing up.

Other options...

Modify a "Christie" stationary generator by hanging the compressor directly on the front instead of the alternator.

Member - Bob replied:

Scott,
there are only 3 options for you:
i. compressor with its own petrol motor (disadvantage is weight)
ii. endless air (disadvantage is space in engine bay)
iii. take cylinders of nitrogen or CO2 (disadvantage is refilling cyls)
Forget about 12 volts, inverters etc. Grossly inefficient, expensive etcBob

srowlandson replied:

If speed is what your after, checkout the New Air-up Co2 Systems.

Refills about $15-20 a fill, dual bottle system is the best.

We have one, and you can't beat it for speed of airing up, and ease of re seating beads. Will operate air tools with ease, and they have a bracket to mount the tank on the spare wheel carrier.

http://www.offroadshop.com.au/air-accessories/

Steve

Member - Eskimo replied:

A standard 1500 or 200 watt inverter is not any good. A 240 motor will take approx 6/7 times full load current to get it going. A compressor has a top and bottom dead centre and this is where the starting current is used. Ask the experts like Jaycar for which inverter will suit that size motor and compressor...and a humble warning....dont expect to be able to afford the inverter to suit.
A belt driven comp is good I believe.

Has any one ever thought of using a cylinder of industrial air or nitrogen ... a regulator is a must. A standard BOC cylinder holds about 2000 psi while my dive cylinder holds about 300 bar (or a bit over 400 psi)

Does any one have any figures on how many tyre fills (275 x 16) you can get out of BOC "D" size cylinder???Wow! am I cute
If yer ain't fishing, Yer ain't livin
Richard

JohnH replied:

As eskimo said, I looked at the BOC type of option, the regulator was a bit pricey, around $300 but the bottles are fairly cheap second hand and pressure tested. The query I had was volume of the cylinder. I think you could manage quite a few refills and for $10 - 20 is worth it I think. All you need to do is establish the voulume in litres of air that your tyres need and then these fellas can work it all out for you. The volume is the hard part. If you figue it all out let us know, I think it's the best option personally.

Good Luck.

JohnH.

Time replied:

Why not buy and install a second "standard" 12V unit and run the two units at the same time, cut the 25 mins in half! Sounds like a lot less hassle to me.

Cheers

Buggerlux

Tony replied:

A mate of mine had a 60 series with "no" room under the bonett, made up a removable bracket that held a A/C compresser and used a ockky strap to tension it, worked a treat, about 2 min to fit up and no time to pump up tyres at a fast idle.

The only other mod was a double pully to run the belt off.

Coops (Pilbara) replied:

Gunzo
I too have 285/75R16's and face a similar problem. One way I counteract is to pump tyres temporarily to 25 psi (this is done rather quickly) and then make my way to the nearest servo at a leisurely pace. You would probably have more access to servos than I also and this might get you around the problem. Other than that I have friends who use a fitting on scuba cylinders, which works a treat too.Allyn
Where to next ?

chrisfrd replied:

I have fitted an E-Air to an 80 series turbo-diesel for a club-mate of mine.

We fabricated the brackets with a mate doing all the welding (electronics is my forte - not welding!) We removed the useless thermo-fan and fitted dual electric units (Davis-Craig) and re-engineered the whole belting system to attach the EA unit atop of the alternator, using an idle-pully and some tensioning points for two smaller belts to drive the alternator and EA unit.

All looks very nice, costed up to be around $300 in brackets, pully wheels, bearings and such.... And he is getting a 40L receiver made up that will bolt directly to the inside of the bullbar.

There's plenty of wasted space in those things. The thing I'm trying to get across is that there are many ways of skinning a cat, it's just a matter of practicing some basic engineering philosophies and making everything up to suit.

Personally, I would never carry cylinders and such, just because they are in the way, they are heavy, cumbersome and potentially stealable (if bolted to the spare wheel that is). KISS... That's the way.....

gunzo replied:

Thanks for all the responses ,youve all talked me out of the inverter/240v compressor option.
Ive found the unit I think Ill go with from an old forum posting, an Oasis 12v winchmotor connected to a auto air conditioner compressor (york) and pumps a very respectable 9cfm @ 50psi (the 24v dose 17cfm @ 50psi) the amp draw however is 120 to 180 amps but as tyre inflation times will be dramaticaly reduced to less than 5 mins for all 4 tyres the load shouldnt be to much for the batery.
The unit costs around $1000 australian dollars. see http://www.oasisoffroad.com/trailheadAirCompressor.html
and so far it is the only unit of its type ive been able to source (there in America)
I hope they can air freight me one , I called them this morning (in US) but there not available to contact till monday 10/11 (there at a trade show).
I called arb and opisite lock but they hadnt herd of this type of compressor
nor were they interested in helping me source one from Australia, dose anyone know of any retail places in Australia who sell these powerful 12v compressors.?
Id rather buy in Australia if I could.
Also has anyone seen one of these things working? ,have a look at the site and tell me what you all think.
Thanks
scott

Matt M replied:

Sounds like alot of expense and alot of work, when a little petrol compressor would do the job nicely!!

Yeah they can be a little weightly but the most is the little briggs and stratton motor, the reservoir could even be mounted under the sill near the chassis rails and utilise a QD for the mounted motor and compressor? That way it could be semi mounted in the vehicle and removed when not needed. The air tanks could then also be fitted with a tyre valve fitting, so that they can be replenished when you can from a servo compressor, allowing a reserve supply on the vehicle even if the compressor isnt on board.

But it that is too much, fitting of one of the top heavy duty 12 pumps with the reservoirs mounted would allow for a large reserve capacity, this really being the problem with inflation times. Then the compressor, using a ARB cutout can just happily run away, topping up the tank when you are back on the road waiting for the next deflation/inflation!!

Its all about reserve capacity if the huge CFM pumps are out of the question, so look for tanks!!!!

Goodluck!

Matt.

Wazza (Vic) replied:

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=2440152476&category=30862

Mate, have a look at this on Ebay - $500, but should do the trick ??Cheers,
Wazza
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