Supplemental Electric Air Compressor

I've put air-assist steering on my M35A2 (besides partially wishing I had went actual power steering), performing low speed maneuvers in a parking lot, or while driving off road over rocks and ruts consumes a lot of air. Typically, this triggers the deuce's low air-pressure buzzer, which is the same point the air-assist is automatically disabled, and this can be tiresome by the end of the day.

I'm not to the point of adding larger/more air tanks to my air system yet, but I though that perhaps adding an additional electric air compressor would noticeably help out - if possible. I do have a separate 12V alternator with a third, dedicated battery for 12v accessories (I didn't want any issues with said accessories the ability to start and run the whole truck).

So, is it possible to just connect another compressor to the air system without adversely affecting the operation of the stock air compressor?

If so, two lines of thoughts, a manual switched, on-demand, air compressor for the tight maneuvering situations such as this (just two examples):

• ARB CKMA12 (2.65 CFM @ 0 PSI, 50% duty cycle) - $275
  • https://www.amazon.com/ARB-CKMA12-Air-Compressor/dp/B009F49NP0/
• Viair 40040 400C Air Compressor Kit (2.54 CFM, 33% duty cycle) - $173
  • https://www.amazon.com/Viair-40040-400C-Air-Compressor/dp/B000FQ78TU/

Or a "always on" or "always available" air compressor (just two examples):

• ARB CKMTA12 '12V' On-Board Twin High Performance Air Compressor (6.16 CFM @ 0 PSI, 100% duty cycle) - $518
  • https://www.amazon.com/ARB-CKMTA12-Board-Performance-Compressor/dp/B0050DI9YQ/
• Viair 45040 450C Air Compressor Kit (CFM @ 0 PSI - 1.66 / CFM @ 100 PSI - 0.94, 100% duty cycle) - $192
  • https://www.amazon.com/Viair-45040-450C-Air-Compressor/dp/B000FQ78VI/

As long as the added electrical air compressor could be set to "turn on" and "turn off" about the same time as the stock air compressor (or turn on later, at a lower pressure), do you see any problems with this? Which type of system would you go with? Obviously higher CFM and duty cycle systems cost much more.

Just add air tanks. Simpler in the long run.

I have the same issue, mostly off road and when I'm backing my trailer up.

I hadn't considered adding a reserve pump. I have an extra tank I was going to add.

There should be no direct issue, but some things to consider:
1) You should set it to shut off at a lower pressure than the stock compressor.
2) I don't know the consumption/pressure requirement of your power steering, but that will dictate which one you have to go with.
3) Consider that adding an additional compressor and the necessary hose/connections will double (or more) your chance of having an issue that may cause you to loose all air in the system. If it was me, I would put one-way check valves in line as you install the new one.
4) Many of the high flow compressors I have seen are rather power hungry. Depending on what else you are running of that battery, make sure your battery is appropriate to handle the constant load.

Stick with military stuff!


PM sent bro

I did want to post (not that I'm peddling ARB wares, but theirs did have some of the best spec's, and highest price) ARB does make 24V versions of the ones I linked above

• ARB CKMA24 - (3.1 CFM @ 0 PSI, 50% duty cycle) - $270
  • https://www.amazon.com/ARB-4x4-Accessories-CKMA24-Compressor/dp/B0050DI9SW/
• ARB CKMTA24 - (6.16 CFM @ 0 PSI, 100% duty cycle, 50A draw) - $518
  • https://www.amazon.com/ARB-CKMTA24-Twin-Air-Compressor/dp/B0050DIA1I/

Attached is the ARB CKMTA12/24 Technical Specs & Product Info PDF.

3.1cfm(max and falls off quick as psi rises) according to the liturature you linked to.

If you do - do something like this, make sure you put a check valve in the feed line!

I still believe added reserve would be your best bet. You could put a pressure protection valve in line, so the aux tanks don't fill up till the main tanks hit a "set" psi.(I would probably do 80psi)

gimpyrobb said:

3.1cfm(max and falls off quick as psi rises) according to the liturature you linked to.

Click to expand...

You know what, good point for the CKM series. An actual intelligent inspection of the graph in that PDF shows that at the air pressure range a deuce would care about for the twin compressor CKMT Series
~3.75 CFM @ 60 PSI
~2.9 CFM @ 90 PSI
~2.6 CFM @ 120 PSI

You must have posted as I was editing. YES 3.1 at zero psi and falling off after that. All of them have less than impressive numbers as far as I'm concerned, They will not see my money.

gimpyrobb said:

All of them have less than impressive numbers as far as I'm concerned

Click to expand...

I think that's the definition of the small DC driven air compressors. Any/all of these listed are pretty pricey for at BEST and rounded up, less than 50% CFM increase over the stock deuce air compressor, which is ~7 CFM.

Thanks for the discussion. If I proceed anywhere, I'll follow up here.

Valence said:

I think that's the definition of the small DC driven air compressors. Any/all of these listed are pretty pricey for at BEST and rounded up, less than 50% CFM increase over the stock deuce air compressor, which is ~7 CFM.

Thanks for the discussion. If I proceed anywhere, I'll follow up here.

Click to expand...

Just add the extra air tanks. I have added over 35 gallons of extra capacity with the two tanks I installed.

Valence said:

I think that's the definition of the small DC driven air compressors. Any/all of these listed are pretty pricey for at BEST and rounded up, less than 50% CFM increase over the stock deuce air compressor, which is ~7 CFM.

Thanks for the discussion. If I proceed anywhere, I'll follow up here.

Click to expand...

I've owned a VIAIR ASK 20000 for 6 years on my 1/2 ton truck and have never had a problem with it. 200psi on a 2 gallon tank. More than enough to air up my 33 inch tires, run an air horn and run an impact for lug nuts. If you go that route you won't go wrong. Ran me about $280 and I installed it myself. If I was going the electric route I would run the p/s just off the electric air source since the p/s is an added on item anyway.

For your situation I would think adding an after market tank would be a cheaper and simpler solution. Few hoses, couple connectors, heck you might even be able to find a tank for free if you know where to look. (Scrap yard!) Bonus to that is you can put whatever size tank you wish, as long as it will hold PSI and fit. Just remember it needs a drain valve..........

Well, with many thanks to Mr. Gimpyrobb, I have finally decided to purchase this military slightly used set of Extreme Outback 24V Air Compressors.

The bonus here is that there are two air compressors and that they already come with rubber isolator feet, switch/relay wiring, and even a short NATO slave plug, and WAY cheaper than brand new. It was just too cool to say no to! I believe I'll mount these up-side-down under the bed, above the fuel tank. Even if I went through water, I better not be even 1/2 that deep!

https://www.extremeoutback.com/prod...Output+24+Volt+Compressor++Part#+007-120.html
Technical Specs:

- Continuous duty fan cooled motor
- 3/4 horsepower motor
- 22 amp draw @ 100 psi
- 1.5 cfm @ 100 psi
- Continuous duty up to 150 psi, Max pressure 200 psi.
- Can be mounted in any orientation
- 14" long, 6" wide, 9", tall



For the record, I think I have enough projects this year now...

Valence said:

Well, with many thanks to Mr. Gimpyrobb, I have finally decided to purchase this military slightly used set of Extreme Outback 24V Air Compressors.

The bonus here is that there are two air compressors and that they already come with rubber isolator feet, switch/relay wiring, and even a short NATO slave plug, and WAY cheaper than brand new. It was just too cool to say no to! I believe I'll mount these up-side-down under the bed, above the fuel tank. Even if I went through water, I better not be even 1/2 that deep!

https://www.extremeoutback.com/prod...Output+24+Volt+Compressor++Part#+007-120.html
Technical Specs:

- Continuous duty fan cooled motor
- 3/4 horsepower motor
- 22 amp draw @ 100 psi
- 1.5 cfm @ 100 psi
- Continuous duty up to 150 psi, Max pressure 200 psi.
- Can be mounted in any orientation
- 14" long, 6" wide, 9", tall

View attachment 665398 View attachment 665401 View attachment 665400 View attachment 665397 View attachment 665396 View attachment 665399

For the record, I think I have enough projects this year now...

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Having worked on these (our mini buses used them for the air bags) I can say I'm pretty sure you won't like the performance out of them. They are great little pumps, and far superior to anything on the market for electric air compressors. In fact I added one to my CUCV but their output and speed of reaching 120 PSI will leave you disappointed. They are also "not" rated for continuous duty like our regular air compressors are. Yes they will reach 150 PSI but then they must be allowed to cool down again unlike a regular compressor which can keep going all day long since it is cooled by the engine oil pumping through it.

rustystud said:

Having worked on these (our mini buses used them for the air bags) I can say I'm pretty sure you won't like the performance out of them. They are great little pumps, and far superior to anything on the market for electric air compressors. In fact I added one to my CUCV but their output and speed of reaching 120 PSI will leave you disappointed. They are also "not" rated for continuous duty like our regular air compressors are. Yes they will reach 150 PSI but then they must be allowed to cool down again unlike a regular compressor which can keep going all day long since it is cooled by the engine oil pumping through it.

Click to expand...

I thought he was installing this for a supplemental/backup? I would think 3 cfm would be quite sufficient for this, and better than extra tanks for build up speed?

Why do they advertise them as continuos duty up to 150psi if they are not? I would hope he will have his cut out before 150psi...

Jbulach said:

I thought he was installing this for a supplemental/backup? I would think 3 cfm would be quite sufficient for this, and better than extra tanks for build up speed?

Why do they advertise them as continuos duty up to 150psi if they are not? I would hope he will have his cut out before 150psi...

Click to expand...

My thoughts too Jblach! At the moment, I think I'd set the electrical air compressors to turn off at about 100-110 PSI and turn on below about 70-80 PSI. They would not run any more continuous than the current engine air compressor, and I do not yet have any plans to expand the air reservoir capacity.

Sparkyz911's idea of using the electric air compressors with a separate tank for the accessories (air-assist steering and air-ride seat) is a sound one, but the air assist is so air hungry that it needs the CFM of the engine air compressor, or you'd need quite a large accessory tank and it would be yet another tank that needs draining...

I have an air drier (that I need to get properly functioning!) and I would prefer to have all the air plumbed together. Carefully. I will need to get:

• A one-way check valve
• A proper fuse block

I am currently considering mounting the following 6-way fuse block.
Rated for 100 amps per block, 30 amps per circuit (but I would prefer a fuse block capable of up to 50A per circuit).
https://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B000THQ0CQ/

And perhaps mounting it inside the battery compartment, behind the battery box, on that back cover, but I will need to check clearances.

Valence said:

My thoughts too Jblach! At the moment, I think I'd set the electrical air compressors to turn off at about 100-110 PSI and turn on below about 70-80 PSI. They would not run any more continuous than the current engine air compressor, and I do not yet have any plans to expand the air reservoir capacity.

Sparkyz911's idea of using the electric air compressors with a separate tank for the accessories (air-assist steering and air-ride seat) is a sound one, but the air assist is so air hungry that it needs the CFM of the engine air compressor, or you'd need quite a large accessory tank and it would be yet another tank that needs draining...

I have an air drier (that I need to get properly functioning!) and it would be preferred to have all the air plumbed together. Carefully. I will need to get:

• A one-way check valve
• A proper fuse block

I am currently considering mounting the following 6-way fuse block.
Rated for 100 amps per block, 30 amps per circuit (but I would prefer a fuse block capable of up to 50A per circuit).
https://www.amazon.com/Blue-Sea-Systems-Blade-Block/dp/B000THQ0CQ/

And perhaps mounting it inside the battery compartment, behind the battery box, on that back cover, but I will need to check clearances.

Click to expand...

Yeh, I wouldn't bother with more tank capacity at this point.

Also, If you don't have the compressor in hand, I would hold off on the check valve, as must conventional compressor setups already have one installed as part of their bleed-off system.

Also, I think the specs posted are for just one of these pumps. The military unit in the pictures has two, so your amp draw at 100psi should be 44A? This will likely be pushing too close for even a 50A circuit, especially as your amps will increase above 100psi.
Let me do some digging, I may have something laying around that will work for you...

Good luck, can't wait to see it installed!

Jbulach said:

Yeh, I wouldn't bother with more tank capacity at this point.

Also, If you don't have the compressor in hand, I would hold off on the check valve, as must conventional compressor setups already have one installed as part of their bleed-off system.

Also, I think the specs posted are for just one of these pumps. The military unit in the pictures has two, so your amp draw at 100psi should be 44A? This will likely be pushing too close for even a 50A circuit, especially as your amps will increase above 100psi.
Let me do some digging, I may have something laying around that will work for you...

Good luck, can't wait to see it installed!

Click to expand...

Thanks for the tip on the check valve! I won't have the compressors in hand until at least next weekend (02/18/2017).

My thought was, each compressor is 22 A @ 100 PSI, so if I wired each one to a separate fuse it'd be within the circuit capacity, but good point - not by much (and each one would certainly pull a few more amperes before they shut off).

These pumps are rated for "continuous" duty up to 150 psi. That means they will not stop until they reach 150 psi. After that they must rest. They have "plastic" seal rings on the piston and the rings will melt if they get to hot. I've replaced a few of them myself. Also the electric motor will get very "toasty" if run to long. I've seen the commutator ring actually melt due to over heating. In all honesty you would be better served getting a spare tank. If you install an "air-dryer" you will only have to drain the "wet" tank on a daily basis. I bought two Stainless Steel tanks off eBay for under $150.00. They will never rust and they add over 20 gallons capacity to my system. You will find with these electric compressors you will be very limited in what you can use when it comes to electrical accessories since they take so much power to run. I'm not trying to "rain on your Parade" here but I'm afraid that after all the time and money spent (heavy gauge wiring and circuit breakers) you will find out they don't work for you.