PTO driven air compressor

[Ideehoan]

I'm thinking of building a PTO driven air compressor for sand blasting. My shop unit puts out about 10 cfm at 90 and its slow.

Harbor Freight sells this:
145 PSI 5 Horsepower Twin Cylinder Air Compressor Pump

If I manifold it with my shop unit I should have decent cfm.

Anyone set something like this up? I guess I need a pto stub shaft for a pillow block setup? Any tips appreciated.

(Tractor is a Kubota B7610)

 

[Ideehoan]

http://www.tractorbynet.com/forums/build-yourself/87592-power-take-off-air-compresser.html

Did some more searching and sure enough someone has done exactly what I was thinking. I had thought too of connecting direct to the flywheel but was unsure how that would work. He did not provide much follow-up to indicate how it functioned and its durability. Seems like a sensible setup. It would however be nice to find a higher capacity pump.

 

[strum456]

I have considered doing the same thing. I think RPMs might be a problem for you. According to the specs for that pump, a standard PTO would be roughly half speed.

My plan was to use a much bigger Gardner Denver pump that I have laying around and run it off my 841 Ford that has a Sherman transmission. This would allow me to run my PTO near 1000 RPMs, which is what most compressors need.

 

[BHD]

this is what I came up with, I have a 540 and a 1000 pto shaft, I do not rember but some where between 50 to 75 cfm at 125 psi,

 

[Ideehoan]

this is what I came up with, I have a 540 and a 1000 pto shaft, I do not rember but some where between 50 to 75 cfm at 125 psi,

I checked yours out when searching. Awesome setup!

strum456
Re: PTO driven air compressor
I have considered doing the same thing. I think RPMs might be a problem for you. According to the specs for that pump, a standard PTO would be roughly half speed.

My plan was to use a much bigger Gardner Denver pump that I have laying around and run it off my 841 Ford that has a Sherman transmission. This would allow me to run my PTO near 1000 RPMs, which is what most compressors need.

I have the 2 speed pto so high speed is in the 900s. I'm going to see if I can luck onto a higher capacity pump but I could get by with the HF unit. High capacity would certainly speed up blasting by allowing larger nozzles.

 

[BHD]

you could start with one pump and if that was not enough add a second and belt drive it off your first pump, I would suggest you add a unloader valve on it some where, (an unloader valve is different than a pressure dump or a safety relief valve) in that it stops letting air in to the tank and diverts it to the atmosphere some (on mine it works internal of the pump) but there are those who just exhaust the pump air separate from the pump,

and example in URL Unloader, Load Genie - Compressor Valves - Air Compressor Accessories - 4TK14 : Grainger Industrial Supply

 

[Ideehoan]

I'm looking at unloader valves. As I understand it, there are different types, the most common being one used to "unload" pressure off an electric motor driven compressor piston when it shuts off, and has a check to prevent tank discharge by reverse flow. In this setting the valve is triggered by air directed to the valve by the pressure actuated switch when it shuts down the compressor. Its function is not pressure control, but easier starts.

Another type is the "pilot unloader" which directs air to an actuator which "unloads" the compressor by idling down a gas engine, or other mechanism. Here it controls pressure by regulating the motor (idling it or actuating valves to prevent compression).

Neither of these applications are intended to control pressure by exhausting air.

I would think a pilot type could be used in that fashion. I'm not sure however, what advantage there is over an ordinary pressure relief valve.

One issue might be service life? I'm not sure a relief valve is intended for repetetive use. Perhaps another thing is noise as a pressure relief valve makes shrill discharge noise. The pilot valve could be directed through tubing to subdue the sound.

Anyone know the answers?

 

[zzvyb6]

A really good idea ! I like this approach because for me it would be for intermittent use only. My shop compressor can run the other stuff, ok.

I had been thinking about a mid-pto compressor, but then I got a rotary 540 air compressor made in Italy to use out in the field for tire service, etc.

So what do you need to complete the sandblaster system ? A blast cabinet (obviously), and a shop vac, but what else? Would you need a reservoir tank and pressure regulator, dryer, etc?

I'm all ears !:thumbsup:

 

[Groo]

While I like the simplicity of a direct drive, based on the low power requirements of the compressor compared tot eh tractor's PTO rating, having the tractor near idle and gearing up the compressor would made more sense. You could also incorporate an electronic clutch easier that way too.

I guess its just a matter of how much time do you want to put into it vs. how much will you use it.

 

[dynasim]

I have purchased the equipment to make a hydraulically driven compressor using the harbor freight 2 cylinder compressor, and a surplus center hydraulic motor.

I am a bit worried about the pressure cycling on the motor, but the power on a 10 gpm flow circuit works out just right. I want to use a pilot driven hydraulic diverter, but will have to see if I can find or make one. The goal is make a compressor that only needs a very small tank(I can adjust the tractor speed to get the compressor capacity I need).

The all in(with a pneumatic unloader) is about 500$ for a 20 cfm, 150 psig, compressor.

The hydraulic part of it should make it safer and easier to use.

Chris