Onboard air with ARB: questions


Hello to all. I just posted this question to the electrical board here, as they have been awesome with helping me navigate and understand what I will do with my electrical system. This does include an electrical question about a compressor, and while this isn't a straight recovery question, the use of lockers will help avoid needing recovery materials...and I do have a winch in mind anyway, so I'll be back with questions about that before too long! :)

So, a lot has come together recently. I have a Daihatsu Rocky, and the offroad bits for it can be hard to source. I'll keep to the point for this thread here: I finally found an air locker for my rig.

Even though the Rocky rear end is essentially a 7" Toyota, you can't simply throw a 7" in there: the axle shafts are all different. I didn't take it apart to see how different, only that sources in Aus say they don't work. An axle swap is much more money and hassle if I don't need to. So, after scouring the interwebz, ProTrack in Greece makes a front and rear air locker for the Rocky (known as a Feroza elsewhere). Enough reviews exist that I'm going to take the plunge.

However, ProTrack's compressor looks like a re-stickered something else, and I'd rather use something available stateside for warranty reasons. I titled this thread for ARB air, but if someone has a different idea, I'm all ears. I have one tech support reply from ARB, but not a second, and the first reply simply told me what models they sell. So, my questions:

I wanted to go with a BlueSea (or something similar) fuse block to wire this into. I would be wiring a switch for the dash to turn the compressor on.
1a. How big a fuse should I be going with for these compressors?

1b. Because someone will ask, and because it's the right question, there is a tiny air locker compressor, and then a single compressor, and then a double. Can the single do a decent job with 30" tires and a locker? (I know this is an electrical forum, but we all like bonus, extra credit questions.)

2. How much space do they need to vent air as they work? I have a nice space in the cab for any of them, and it's centrally located under the front seats, but I know they need to breathe and not get too hot.

Any help here is great. I appreciate the help in advance!


I have the dual ARB compressor paid about 500 bucks for it. ARB has all of the kit you need for switches, battery wiring, relays. And a tiny tank for the plumbing. I’m sure they have a different name for it. I have it installed in a Jeep Wrangler in the engine compartment. It has aluminum fins on it as a cooling device. Two ports on tank , one for my lockers and one for a hose I run through the front. ARB has a nice flexible soft hose I attach to the other hose. Airs up my 35” tires in no time.


Active member
Most any compressor will fill a tire, it is just a matter of how long it will take. ARB makes great compressors, but there are others that may do what you want for a price you prefer. All compressors need to both take in clean or filtered air and to dump the wast heat from compressing. Not all compressors can survive in an engine bay like the ARB's can. If you mount one elsewhere, make sure it has enough heat sinks/insulated mounts/ clearance to not light anything on fire. Often they can get too hot to touch quite quickly. Whatever you get, run it for a full duty cycle and see how hot it gets before you install it.

Re the fuse, it depends on the length and thickness of the wire you run to the compressor from the battery.
Nameplate on the compressor tells you where to start, distance to the battery (and back, you can run a pair of wires as fast as one and skip the hassle of grounding to the frame alone) will tell you what size wire you need to keep the voltage where it will not damage the compressor (compensating for voltage drop). The fuse is sized to protect that wire from catching on fire or other mishaps. Blue Sea publishes a number of helpful charts to work through this quickly and safely

They also have a pair of articles to explain the process and point you to the products they make that may serve you best

Another option is to skip the compressor and use a CO2 tank, which will fill your tires quickly and engage your locker seamlessly, but only a finite number of times before you need to refill it. You would still wire a switch to a solenoid to activate the locker, but that would be pressurized by a regulator on the tank, which is also where you would attach your tire inflator. The tanks need not be big nor new, necessarily, and will get cold with use and not hot. It has fewer moving parts and installed components, but you need to refill the tank eventually.