On
Board Air (OBA)
If
you need air to power tools, the garage isn't the
only place to call home. A great ption, such as below,
is to simply make your own onboard air system. If
you have the money, feel free to buy any of the commercially
available units.
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The
round black object (below the yellow arrow) with two
wires coming off it mounted to the first T of the
manifold is the pressure switch from Air Ride Technologies.
Kilby uses a similar unit. It is strongly recommend
to spend the extra time (not really that expensive)
finding one of these smaller switches rather than
using one of the bigger, regular air compressor type
that you can get almost anywhere.
The
next two T's are merely for the front and rear hoses
to exit from. Pretty self-explanatory. The third and
last T in that picture is a little harder to see,
as it is turned somewhat differently from the others.
This was to enable the pressure gauge to be read more
easily. That gauge was found at Harbor Freight. The
end of the manifold is the 150-psi pop off valve.
You really must use one of these. If you don't
and the pressure switch fails, the compressor could
run until either it or any one of many components
suffers a catastrophic failure. (bad!) The switch
used is for 130-psi. They have one for 150-psi, but
it is best to have a margin of 15- 20-psi between
the switch's rating and that of the pop off valve.
Otherwise, the pop off valve will open up every-time
the compressor shuts off.
The
last picture shows a close up shot of the filter,
the inline oiler, and the unloader/ one way valve.
The unloader valve unloads the pressure from the compressor
side of the manifold after it shuts off- this is so
it does not have to start up against a load. The one-way
valve does just what it sounds like- it only allows
air to travel in one direction- from the compressor
to the manifold, in this case. It really is a pretty
simple thing to do.
Two more recommendations:
First:
Do not use Teflon Tape- instead, go to your parts
store and purchase a bottle (can?) of liquid Teflon
(it is applied with a small brush that is built into
the cap.
Second: Be very careful when installing any
reducer bushings, so that you do not deform them.
I put the reducer bushing for the pop off valve in
the manifold before I had put the valve in it, and
due to the soft properties of the brass, I partially
smashed it. Even though I did my best to fix it, and
used extra Teflon, it still leaks. The result is that
all my air leaks out a few minutes after I shut it
off.
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The
wiring goes as follows:
Fused
12 volts enters the cab, and goes to a toggle switch.
From there, it goes back out to the pressure switch
(PS), out of the PS to a relay, and from the relay
to the compressor clutch. You will notice that there
are 2 wires at the clutch. Use both of them. I simply
crimped both of them in the same connector.
The oiler works as follows:
You
fill it with air tool oil, and as you imagined, there
is a tiny orifice (hole) that it is drawn through
as air flows through the inlet side. It seems to work
ok, but the oiler I have (it was free) is quite difficult
to fill without making a huge mess, so I have been
simply lightly soaking the filter itself (on the top
side only) with the air tool oil, and allowing it
to be drawn from there. No more often it runs, and
the duration being as short (relative to it's designed
use as an AC compressor that runs nearly continuous)
as it is. I think either or both methods would be
sufficient. I currently have no plans to add a separator.
I hooked a blow-gun to the hose and blew it through
a piece of cloth (shop rag), and the amount of oil/
moisture that collected on the rag was negligible.
If you were planning to run air tools, or perhaps
an ARB, you may need to add a separator.
The
relay is pretty simple. There are instructions on
the packages of most of the ones I have ever bought.
It gets fused 12 volt + power (25 amp), chassis ground,
switched power (more on this later) and output power.
Switched power is 12 volts+ coming from a switch (toggle,
for example). I ran a 5 amp fused power wire into
the cabin, and into a toggle switch. From the toggle,
I ran a wire out to the engine compartment to one
side of the pressure switch (PS). From the other side
of the PS I ran a wire to the switched power terminal
of the relay. So basically, when I need air, I turn
it on at the toggle switch. The PS determines whether
there is a need for the compressor to run (mine comes
on below 115-psi, and shuts off at 130-psi). If it
is below 115-psi, it connects and sends 12 volts to
the switched power post of the relay. This triggers
the heavy duty switching terminals inside the relay,
and sends power to the compressor clutch, engaging
it. Ta-Da! We have air.
One thing that I am going to change, is the copper
tubing that runs from the compressor outlet to the
air "manifold" at the passenger side fender.
I do not have the manifold securely mounted at this
point due to the fact that it is more or less stiffly
connected to the comp. As you know, the engine can
twist in place slightly, and the fender does not.
If I were to mount the manifold to the fender, the
copper tubing could either be pulled apart from it's
fittings, or fatigue over time and rupture. I am going
to replace a portion of it with 3/8 or 1/2" air
hose, and mount the manifold.
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