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ExtremeAire OBA

A couple of weeks had gone by since Mike and I worked on his OBA setup.  During that time, he painted the rack and ordered a few project parts from an on-line  store.  When they arrived, I headed over to his place to see if we could make some more progress.


Mike decided to use a Maxi fuse for the main power feed to the ExtremeAire compressor.  The holder was obtained and a 60 amp fuse was found at the local ACE hardware store (it never ceases to amaze me as to the variety of "stuff" that store carries).  We put terminal lugs on the 8 gauge pigtails and made it ready for installation between the positive terminal of the battery and the control solenoid.



You can see a portion of the control solenoid in the above picture.  8 gauge audio amp power cable connected the output terminal of the control solenoid to the positive power lead of the compressor.  A butt splice was used to connect the leads at the compressor.  The negative lead of the compressor motor was connected to one of the nearby mounting fasteners using a crimp on ring terminal.  The chassis ground for the negative lead worked just fine, as we later confirmed.  The control solenoid was mounted on the passenger front fender well, about 6 inches from the battery.  This location allowed the Maxi fuse holder to be used without the need of splicing an extension to the holder's leads.



Mike had a spare ARB pressure switch which he pressed into service when he realized that the one he had ordered had yet to arrive.  A "T" was put in one of the 1/4" NPT bungs on the tank and to it was connected the ARB pressure switch and a 150 PSI pop-off safety valve.  The safety valve will automatically open and release tank pressure should the pressure switch malfunction and not turn off the control solenoid when the 105 PSI upper regulator limit is reached.  Before wrapping it up, we put some heat shrink tubing on the pressure switch's electrical connectors.  You would not want those +12V terminals exposed even though the solenoid control circuit is protected with its own 15 amp fuse.  The remainder of the control solenoid circuit is a dash mounted power switch.  When the dash switch is turned on, tank pressure is controlled completely by the pressure switch.  When turned off, the solenoid will not energize and the compressor will not maintain tank pressure.



3/8" soft copper line was used to connect the compressor to the tank.  It was decided to put a few coils in the line to help dissipate the heat that is generated by compressing the air.  I thought it was a great idea since it is about the prefect size to heat a can of soup.  (I wonder how many tires have to be filled before the soup is ready?)  We found that the fire extinguisher made a good form on which to bend the copper line.  90 degree compression fitting were used on the copper line at the output of the compressor and the inlet of the 1 gallon tank. 

Just in case anyone is wondering, the mounting rack as designed is more than strong enough to hold the compressor and tank in position.  We used large fender washers inside the wheel well where the 5/16" fasteners secure the rack.  Nyloc nuts were used to help ensure things did not vibrate apart.  Once we had tightened the mounting bolts, we found that we could rock the vehicl side to side by pulling on the rack.  Yep, it was not going anywhere.  A friend of mine was concerned that the 3/16" strap would not be up to the task.  I believe he will change his mind once he sees it first hand.  (You can see the second bracket that Mike added, under the compressor.)

Once the air line quick disconnect is screwed into the tank, this part of the project will be done.  I asked a friend of mine to bore a hole through the middle of some 1"  aluminum round stock.  The plan is to use a 6" long piece, drilled and tapped for the appropriate fittings, as an air manifold for the ARB compressor solenoids.  This will allow Mike to use the ARB compressor or the ExtremeAire as a pressure source for his ARB lockers.  Switching between the two will be as easy as moving the quick disconnect from one compressor to the other.

When we get that part finished, I'll snap a few pics and include them in this write-up so I can call this done.

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