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Double-Duty Compressor: ARB Twin-Motor CKMTA12 Air Compressor

Posted in How To on June 1, 2012 Comment (0)
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Years ago, we used to enjoy watching diehard ARB-equipped off-road enthusiasts stubbornly (and slowly) fill up their tires using their own ARB on-board air compressors—even when another air source was near. While we admired the loyalty, there were better options to fill up tires back then. Those first ARB air compressors were originally designed for running air lockers, and the duty of filling large off-road tires was really more than the compressors could handle in a reasonable amount of time.

But that’s something in the past. ARB is very aware of how enthusiasts use their products once they come to market, and as tires got larger on 4x4s, ARB reengineered their compressor line to keep up with what today’s off-roader needs.

First the CKMA12 hit the market, able to not only run air lockers but also able to produce 2.18 cfm while under a 20-psi load. This was a high-performance mini compressor that was so impressive that enthusiasts started installing them solely for filling up tires. Now, ARB has finally released the highly-anticipated twin-motor CKMTA12 air compressor that more than doubles the air output of the single-motor compressor.

With 41.5-inch tires and two ARB air lockers on our ’03 crew cab Super Duty, we figured it was the perfect recipient of a twin-motor compressor that we’ll put through the paces over the next few years.


01. The CKMTA12 twin-motor compressor is still a 12-volt accessory, but it takes a fair amount of amperage (up to 50 amps) to run both those high-performance motors. The result is a whopping 4.65 cubic feet per minute of air when under a 20-psi load. We also got the optional solenoid manifold kit that gives us two ports to connect each of our ARB air lockers to, and an extra port to run an air line for filling tires or running air tools.

02. The CKMTA12 has a larger wiring harness and two large blade fuses since it has two of the same motors that the CKMA12 holds. The benefits of the smaller singe-motor compressor are its compact size and its built-in solenoid manifold while still being a high-output compressor. The twin-motor CKMTA12 does pump more than twice the air output (than the single-motor compressor), but also takes up more than twice the room and needs a remote solenoid manifold mounted somewhere in order to run air lockers.

Model Voltage Current @ 0 psi Air flow @ 0 psi Current @ 20 psi Air flow @ 20 psi Weight Duty Cycle Size
CKMA12 Single-Motor Compressor 12 V 13 A 2.65 cfm 22.9 A 2.18 cfm 9.9 lbs 50% 5.6x7.5x3.8
CKMA12 Twin-Motor Compressor 12 V 28 V 6.16 cfm 50A 4.65 cfm 19.4 lbs 100% 4.0x7.5x10.8

03. While the ARB compressors are designed to work under your hood or even under the body, you ideally want to keep your compressor out of harm’s way in a well-ventilated area, away from the reach of elements and extreme heat—just as you would any piece of electric hardware. With barely enough room under the rear seat of our crew cab, we squeezed our twin compressor into the cab after adjusting the manifold cap so the outlet port (to the solenoid manifold) sat at an angle. McComas Auto Body cut an aluminum plate out to mount the air compressor to our rear seat’s lower brackets instead of drilling through the floor.

04. We mounted all three ARB switches (one compressor, one front locker, and one rear locker) on an aluminum panel we picked up at T and J Performance. We routed the wiring along the carpet’s edge and from the compressor to the switches (the switch harness is connected to the main compressor harness).

05. Though the CKMTA12 twin-motor air compressor can run some air tools, you might want an auxiliary air tank if you’re going to use more demanding units like 150-psi air impact guns. ARB offers this new forged aluminum 1-gallon air tank that has the same JIC4 port fittings as the ARB air compressor and plumbs in between the twin-motor compressor and the solenoid manifold. Since every customer will have different length hose requirements, ARB does not include this line and we had to get our own air lines at a local hydraulic line store to plumb the air tank into the system.

06. ARB also has an optional Tire Inflation Kit you can add to your package. It comes with a T-fitting to mount on the air manifold, a high-heat pressure hose, and an ARB air chuck. It’s recommended over standard air hoses because it will handle the air temperatures associated with the high-output ARB compressors.

07. With both compressor motors triggered, we were able to fill up our 41.5-inch Pit Bull tire from trail pressure to street pressure in a little less than half the time it did with the single-motor compressor since the load of the tire’s air pressure is distributed over two compressor motors.

08. We could get the lugs off our wheels with a 150-psi impact gun and the ARB 1-gallon air tank in place, but the impact gun worked better if we let the tank charge up in between wheel removals.

Sources

McComas Auto Body Inc.
San Jacinto, CA 92583
951-654-7293
http://www.mccomasautobody.com
T And J Performance
714-633-0991
http://www.tandjperformance.com
ARB USA
Renton, WA 98057
866-293-9078
http://www.arbusa.com

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