jjohnsonphx
Observer
Building an Off-Road Compressor
Off road traction, Tire pressure, Air Compressor, Motor, Lots of money,
Wake me up!
By now most of us know that lowering tire pressure equals better traction when off-road. The only problem when off-roading is not lowering the pressure, but putting that air back into your large tires in a reasonable amount of time. Your local auto parts store air compressor that runs off 12V just won’t do. If your like me you have already tried that and found that 4 tires would take anywhere from a half to a full hour. This got me to thinking, why can’t I make a compressor that can do the job in about 5 minutes for all 4 tires.
Many after market manufactures are making good compressors and even ones that I could by off the shelf to meet my goal. One that comes to mind is the Oasis compressor made from a York AC pump. This would defiantly do, but the price is way too much for my wallet. But I like the idea.
I started out this project in mind with saving a load of cash, and ended up saving but not nearly as much as I thought I could. I found a mini Tecumseh AC compressor at my Dad’s shop for free. I can’t beet that price anywhere else. I rebuilt the gaskets on the read valve assembly to make sure the pump worked as good as new. While I had the pump apart I might as well estimate the dimensions so I know how much air the pump will output. The piston stroke measured out to 1.89 inches at a diameter of 1.87 inches, so that makes it about a 5.2 cubic inch pump. This should put out plenty of air. Although I chose a Tecumseh, just about any AC pump that has an oil sump will do. If you choose a pump without an oil sump you will have to add an oiler to the mix.
Picture of pump:
I chopped off the hoses from the original AC fittings and taped them for ¼ NTP pipe thread. This would allow me to use standard air fittings throughout the rest of the project. On the intake side I used a small cloth filter that I found at my local parts store. Nothing would be worse than dirt shortening the life of the pump or getting into the air tank and eventually into my tires. On the exhaust side the chopped AC fitting leads the air through a one way check valve to keep the air from slowly leaking back through the pump when it is off. The check valve leads to a tee that splits the air to an over pressure valve and the pressure switch. Remember for safety reasons an over pressure valve should always be used.
Close up of the fittings:
Next I needed something to power the pump. My first thought was to use the engine of my 2000 Jeep Cherokee. But after further inspection I couldn’t find a single place that had enough room to mount the pump.
So I decided to turn to a self contained unit. I found Western Motor Service Company in Rockford Illinois. They had a motor that would fit my need. The model W-8963 is a permanent magnet, 12 to 24Vdc, slot shaft, single rotation motor. You can find them on the web at http://www.wms1.com/. The motor was the single most expensive part of the entire project at $200.00.
Picture of motor:
Now that I had the major components it was time to ask a machinist friend of mine to make a shaft to mate the two parts together. Thanks to Kurt I had a perfectly machined shaft in about 2 weeks.
Picture of shaft installed on pump with lock washer:
Now all I need is a bracket to hold the two together. I went down to my local metal yard and found some 10 gauge 5 inch wide steel that would work perfectly. At only 33 cents a pound for scrap I ended up paying only 3 dollars. I mated the pump to the motor so I could draw what I had in mind. After taking many measurements I cut one 5 inch by 5 inch piece for the motor plate, and two 5 inch by 5.5 inch plates for the sides. The top plate was mainly for mounting the solenoid and on/off switch, so the size wasn’t critical. Since this was my first welding project I practiced on some left over pieces of metal.
Picture of the bracket:
The bracket came out pretty good for my first welding project.
With the bracket completed all that was left was to paint the bracket, and put the compressor together.
Picture of completed compressor:
Wiring the motor wasn’t too much of a challenge; it’s like wiring a starter. I used a 6 dollar Ford starter solenoid to power the pump. A heavy duty switch and a Military cover were used to turn on/off the solenoid. Don’t forget that a motor of this type will pull lots of current, so use number 4 or larger wire to the main power source. The solenoid can be powered (controlled) off a lighter gauge wire like number 14 or 12 along with the pressure switch. Remember to wire the pressure shut off switch after the main on/off switch then to the solenoid. This way the main on/off switch will shut off the motor regardless of the pressure switch position.
And there you have it. A self contained compressor that can air up all 4 of my 33” tires from 12lb to 32lb in 5 minutes 42 Seconds flat. I did find out I have to run the engine to recharge the battery after the second tire. Well, if I want to start the Jeep after airing up. I only made that mistake once.
Cost
Motor 200
Compressor Free
Starter Relay 6
Misc fittings 15
Pressure switch 10
Wire Laying around the shop Free
Switch and military cover 6
Steel 3
Mating shaft (old bolt machined) Free
Off road traction, Tire pressure, Air Compressor, Motor, Lots of money,
Wake me up!
By now most of us know that lowering tire pressure equals better traction when off-road. The only problem when off-roading is not lowering the pressure, but putting that air back into your large tires in a reasonable amount of time. Your local auto parts store air compressor that runs off 12V just won’t do. If your like me you have already tried that and found that 4 tires would take anywhere from a half to a full hour. This got me to thinking, why can’t I make a compressor that can do the job in about 5 minutes for all 4 tires.
Many after market manufactures are making good compressors and even ones that I could by off the shelf to meet my goal. One that comes to mind is the Oasis compressor made from a York AC pump. This would defiantly do, but the price is way too much for my wallet. But I like the idea.
I started out this project in mind with saving a load of cash, and ended up saving but not nearly as much as I thought I could. I found a mini Tecumseh AC compressor at my Dad’s shop for free. I can’t beet that price anywhere else. I rebuilt the gaskets on the read valve assembly to make sure the pump worked as good as new. While I had the pump apart I might as well estimate the dimensions so I know how much air the pump will output. The piston stroke measured out to 1.89 inches at a diameter of 1.87 inches, so that makes it about a 5.2 cubic inch pump. This should put out plenty of air. Although I chose a Tecumseh, just about any AC pump that has an oil sump will do. If you choose a pump without an oil sump you will have to add an oiler to the mix.
Picture of pump:
I chopped off the hoses from the original AC fittings and taped them for ¼ NTP pipe thread. This would allow me to use standard air fittings throughout the rest of the project. On the intake side I used a small cloth filter that I found at my local parts store. Nothing would be worse than dirt shortening the life of the pump or getting into the air tank and eventually into my tires. On the exhaust side the chopped AC fitting leads the air through a one way check valve to keep the air from slowly leaking back through the pump when it is off. The check valve leads to a tee that splits the air to an over pressure valve and the pressure switch. Remember for safety reasons an over pressure valve should always be used.
Close up of the fittings:
Next I needed something to power the pump. My first thought was to use the engine of my 2000 Jeep Cherokee. But after further inspection I couldn’t find a single place that had enough room to mount the pump.
So I decided to turn to a self contained unit. I found Western Motor Service Company in Rockford Illinois. They had a motor that would fit my need. The model W-8963 is a permanent magnet, 12 to 24Vdc, slot shaft, single rotation motor. You can find them on the web at http://www.wms1.com/. The motor was the single most expensive part of the entire project at $200.00.
Picture of motor:
Now that I had the major components it was time to ask a machinist friend of mine to make a shaft to mate the two parts together. Thanks to Kurt I had a perfectly machined shaft in about 2 weeks.
Picture of shaft installed on pump with lock washer:
Now all I need is a bracket to hold the two together. I went down to my local metal yard and found some 10 gauge 5 inch wide steel that would work perfectly. At only 33 cents a pound for scrap I ended up paying only 3 dollars. I mated the pump to the motor so I could draw what I had in mind. After taking many measurements I cut one 5 inch by 5 inch piece for the motor plate, and two 5 inch by 5.5 inch plates for the sides. The top plate was mainly for mounting the solenoid and on/off switch, so the size wasn’t critical. Since this was my first welding project I practiced on some left over pieces of metal.
Picture of the bracket:
The bracket came out pretty good for my first welding project.
With the bracket completed all that was left was to paint the bracket, and put the compressor together.
Picture of completed compressor:
Wiring the motor wasn’t too much of a challenge; it’s like wiring a starter. I used a 6 dollar Ford starter solenoid to power the pump. A heavy duty switch and a Military cover were used to turn on/off the solenoid. Don’t forget that a motor of this type will pull lots of current, so use number 4 or larger wire to the main power source. The solenoid can be powered (controlled) off a lighter gauge wire like number 14 or 12 along with the pressure switch. Remember to wire the pressure shut off switch after the main on/off switch then to the solenoid. This way the main on/off switch will shut off the motor regardless of the pressure switch position.
And there you have it. A self contained compressor that can air up all 4 of my 33” tires from 12lb to 32lb in 5 minutes 42 Seconds flat. I did find out I have to run the engine to recharge the battery after the second tire. Well, if I want to start the Jeep after airing up. I only made that mistake once.
Cost
Motor 200
Compressor Free
Starter Relay 6
Misc fittings 15
Pressure switch 10
Wire Laying around the shop Free
Switch and military cover 6
Steel 3
Mating shaft (old bolt machined) Free
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