Air Compressor 12 volt pressure switch

[czechsonofagun]

I would search on Jeep and OBA (On Board Air)

 

[Wombat125]

I would search on Jeep and OBA (On Board Air)

That's the ticket. The easiest way by far to do this is to go to the boneyard and get a compressor out of a car. Almost all cars have either a York or a Sanden compressor. They're easy to tell apart because the York looks traditional with fins and its own oil sump. The Sanden is barrel shaped and lubricated by the refrigerant.

I have a Sanden on my Samurai because it was already on my swapped-in 1.6L Tracker motor. Since I have no refrigerant, I shoot WD-40 down the intake every time I use it. I know it will die one day soon, but replacements are only $30.

Anyway, they are so easy because they have the belt driven clutch already on them. Just need 12v to turn it on and off.

For a pressure switch (I guess that was the original question), I just got a cheap 130lb pressure switch from the local farm store. That, plus a pressure gauge, some air fittings, and a switch were under $30. Took about an hour to hook it all up.

Automotive air compressors are *FAST*. I can air up a 31x1050 tire in just a couple minutes with no air storage tank. Makes those little 12v compressors look silly.

As previously stated, Kilby Enterprises build fancy pants York based systems. They're super nice, by you pay through the nose.

 

[allenr]

What kind of magnetic clutch is that?

I was just thinking I'd get a PTO clutch off the bottom of a lawn mower, but yours looks different.

It's a Warner Electric No. 5215-57.

Didn't come with a pulley, just a flange with 4 1/4UNF theaded holes.

I was told when I bought it that given the "jumpy" rotation of a i/c engine I should fit a Tyre coupling. I just fitted a chain coupling I had lying around.

The rivets at each end of the three "springy" flats that transmit the drive when engaged began to break, so finally fitted a tyre coupling but only after the clutch. (this was midway through the first season)

This season had a bit more trouble including one springy flat breaking by the rivet. Have now fitted thicker and wider spring flats (blades from a DeWalt recipro saw) and bigger (5/16) rivets.

Survived the last 2/3rds of this season OK.

In reply to the guy who questioned volts/amps/watts my understanding is that for the same watts you need heavier wiring, contacts etc when those watts are coming in 12V and obviously higher amps than when it is 240volt and low amps.

 

[srjones]

It's a Warner Electric No. 5215-57.

Didn't come with a pulley, just a flange with 4 1/4UNF theaded holes.

I was told when I bought it that given the "jumpy" rotation of a i/c engine I should fit a Tyre coupling. I just fitted a chain coupling I had lying around.

The rivets at each end of the three "springy" flats that transmit the drive when engaged began to break, so finally fitted a tyre coupling but only after the clutch. (this was midway through the first season)

This season had a bit more trouble including one springy flat breaking by the rivet. Have now fitted thicker and wider spring flats (blades from a DeWalt recipro saw) and bigger (5/16) rivets.

Survived the last 2/3rds of this season OK.

In reply to the guy who questioned volts/amps/watts my understanding is that for the same watts you need heavier wiring, contacts etc when those watts are coming in 12V and obviously higher amps than when it is 240volt and low amps.

Allenr, that's quite a setup of you've got there. I've got a back-burner project I've been thinking about for while and you've given me an idea of how to solve one of the problems. But, if I could ask:

1. At what RPM speed does the compressor rotate?
2. I don't see a fan or the original flywheel which probably has a fan, so do you have issues with it over heating? By mounting it front of the engine near the radiator fan does that help with cooling?
3. What type of pruning tools do you use that use compressed air as the power source?

 

[Soundguy]

In reply to the guy who questioned volts/amps/watts my understanding is that for the same watts you need heavier wiring, contacts etc when those watts are coming in 12V and obviously higher amps than when it is 240volt and low amps.

You may want to hit an electronics 101 class for a brush up on ohms law.

If the switch contacts are rated for the correct total sustained power disipation.. it will be fine...

soundguy

 

[allenr]

Allenr, that's quite a setup of you've got there. I've got a back-burner project I've been thinking about for while and you've given me an idea of how to solve one of the problems. But, if I could ask:

1. At what RPM speed does the compressor rotate?
2. I don't see a fan or the original flywheel which probably has a fan, so do you have issues with it over heating? By mounting it front of the engine near the radiator fan does that help with cooling?
3. What type of pruning tools do you use that use compressed air as the power source?

Thanks SR.
1. I run the engine at idle, it doesn't have a tachometer but I'd guess it to be 7 - 800rpm like larger tractors. Might rev it up a bit for initial pump up in the morning.
2. Yes the original pulley had a fan built in. Presumably the engine fan creates a little bit of air movement. Mostly rely on the fact that it is running at much less than the 1500 max rpm and probably only turning 50% of the time. It doesn't get hot.
3. It generally runs 2 or 3 Ofma & Felco pneumatic secateurs which have a cylinder that fits in one hand.

Links to the compressor and air snips below.

http://www.forbesaust.com.au/new/pdf files/SV201 facts.pdf

Felco SA - Les produits Felco SA

 

[allenr]

You may want to hit an electronics 101 class for a brush up on ohms law.

If the switch contacts are rated for the correct total sustained power disipation.. it will be fine...

soundguy

Soundguy, I have absolutely no training in things electrical.

If you can explain what ohms has to do with the contacts, without being too technical - I'm willing to listen.

 

[Soundguy]

The contacts will have a power disipation rating.. ohms are basically the resistance in the circuit. Depending on source voltage, ohms will determine the amps flowing in the circuit. With amps and supply volts you can determine power.. or wattage.

E=IR
IE=P

With those two equations.. you can do all the calc's yourself. There are other 'issues' for AC circuits as opposed to DC.. but for generic 'go/no-go' calc's.. this will get you there.

soundguy

 

[Iplayfarmer]

I looked around again and found a pressure switch on e-bay. It's not adjustable, but it will do quite nicely. For 99 cents I can't beat the price.

Campbell Hausfeld air compressor switch Pressure NICE!! - eBay (item 230291450680 end time Sep-21-08 18:07:43 PDT)

I also got a guage, pop-off valve, and some other stuff from the same guy. so shipping is real reasonable.

 

[BobRip]

The contacts will have a power disipation rating.. ohms are basically the resistance in the circuit. Depending on source voltage, ohms will determine the amps flowing in the circuit. With amps and supply volts you can determine power.. or wattage.

E=IR
IE=P

With those two equations.. you can do all the calc's yourself. There are other 'issues' for AC circuits as opposed to DC.. but for generic 'go/no-go' calc's.. this will get you there.

soundguy

Soundguy, electrical contacts have a different rating on DC versus AC. It is usually lower on DC. AC cuts on and off and so the arc between the contacts self extinguishes when the voltage drops to zero. With DC the arc can last a lot longer. Will it be a problem? Probably not since the well switch contacts are rated at typically around 20 amps AC and you are pulling less than 5 DC. Put the two sets of contacts in parallel (if it's 220 volt) and that will help.