12 volt York based OBA

[bigtigexplorer]

I currently have a 10 cubic inch York compressor sitting at my house. My plan is to install it in my Bronco project, but it's going to be awhile before I can really dig into that project so here's my idea.

The other day I was looking at http://www.kilbyenterprises.com and came across their HP1000 and XD2000 12 volt compressors:

So I thought since I've already have the York compressor, all I really need is the motor and I can build my own 12 volt OBA system. Which I could then mount where my spare tire used to be and actually use my York instead of watching collect dust in my house.

The Oasis compressors are using modified 12-24 volt 5hp winch motor which is directly attached to the York compressor's shaft, I think the hardest part about making this work would be finding a suitable motor.

For those of you wondering why I don't run the York off a pulley in the engine bay, mainly because I don't want to mess with relocating anything in the engine bay to make room for the compressor. I also like that I could run the compressor directly off the battery, even if only for a short time, should the engine be dead.

So ideas, comments, questions?

 

[bigtigexplorer]

Bump

After some searching I found this replacement winch motor that might do the job. I'm waiting on the specs and pricing from the dealer.

Assuming this motor will work. I just need to figure out how I can connect the staft of the motor to the input shaft of the compressor.

Any Ideas?

 

[Gladi8r]

..........

Assuming this motor will work. I just need to figure out how I can connect the staft of the motor to the input shaft of the compressor.

Any Ideas?

Look in a Graingers or McMaster Carr catalog or website and look for standard "LoveJoy" style flexible couplers. They can be had for just about any shaft diameter and allow for any slight mis-alignment between items. Or, you could just make one from solid steel stock and have he shaft diameters bored to match the motor and pump, then use set screws to secure them to the shafts. Good luck with your project.

 

[bigtigexplorer]

The shaft on the compressor may be an issue though, because it tapers. Here's a link to the detailed spec sheet of the york compressor.

I looked through the Grainger and McMaster Carr online catalog and I think a spider coupling like below would work great but I haven't seen any that would fit the taperd shaft of the York compressor.

Here's a simplified picture of the two shafts:

 

[Gladi8r]

I am almost positive that you can buy those couplers as blanks( no center holes drilled and keyed).
If so, buy a blank and have a local machine shop do the 1/4" taper for you and broach it for a keyway.
It may also be possible to turn the compressor shaft to remove the taper if you already have it apart for rebuild.

 

[sparkmechanic]

Try Dodges catalog. NOT the automotive one. They have all kinds of good stuff. PM me and I will find the web site @ work in the AM.

 

[Gladi8r]

Here is the link for Dodge

 

[Robb]

hmmmmmm, I wonder how hard it would be to pull the shaft and have a machine shop lathe the taper out of it.

 

[bigtigexplorer]

I was looking through one of LoveJoy's catalogs for Curved Jaw Type Couplers and at the bottom of page 11, I saw their spider to flange coupler and it hit me. I did a quick break-out drawing below, what do you guys think, will it work?

 

[Gladi8r]

Without the flange being keyed to the York shaft, I doubt it would work. The flange would just spin on the bolt it is attached to the shaft with. I think the easiest and most cost effective is to just get a blank flange or one that is the size of the smaller diameter of the taper and have it bored to match the shaft. Another thing, you may not be thinking about.....what RPM is the motor turning at?? The York is rated at 10.3 cubic inches of displacement @ 6000 RPM. If the motor is turning at 1750 or so, as most are rated, then your displacement will be affected severly. You might want to check into this.

Not trying to pee on your parade, just trying to give you food for thought

 

[Robb]

The York is rated at 10.3 cubic inches of displacement @ 6000 RPM.

How does a compressor, run of a drivebelt of a piston engine, turn at 6000rpm? Or is that peak? It will still produce pressure at idle, say 500 crank rpm, and the sheave ratio isn't very different between the crank and compressor.

edit: and there are plenty of 3450 motors to choose from

 

[Gladi8r]

You are correct, it will still produce at just about any RPM, however with it attached to a belt under the hood the RPM can be controlled using the throttle. You will not have that luxury with an electric motor. And, yes, there are other motors with higher RPM's, I was just throwing this out for him to keep in mind when he purchases a motor. I just wanted him to be careful on what size motor he was buying. Just because it is a 5HP motor for example, does not mean it will be the "ideal" motor for his application. He needs to keep RPM's in mind also.

Just trying to give him things to think about prior to spending his hard earned money.

 

[Robb]

That's cool, and I understand. The more we discuss here, the more we help.

And I think you bring up an excellent point that may have been over looked, in regards to rpm. Most motors (I am more familar with AC than DC) will be wound to run +/- 1725. This may not be as productive to the compressor as running a 3450 rpm motor (another common size, but not as common).

I have no idea how to determine an optimal HP needed.

 

[bigtigexplorer]

Glad I'm not the only one thinking about RPMs. The motor I listed about is rated at 6000 RPM minimum, according to the York's specs, 6000 RPM is it's maximum RPM rating. However I don't think it would be a good idea to have the compressor spinning at it's max RPM every time it's in use.

With a little more research I found that the Oasis HP1000 compressor runs at 1650 RPM @ 50 PSI producing 9 CFM. So if you double that RPM to 3300 RPM you get 100 PSI and according to their specs you can get 8 CFM @ 100 PSI. I figure most air tools run at around 90 PSI.

Originally Posted by Gladi8r
The York is rated at 10.3 cubic inches of displacement @ 6000 RPM. If the motor is turning at 1750 or so, as most are rated, then your displacement will be affected severely.

This may be a common misconception, but displacement is not linked to RPMs. That's kind of like saying my engine is a 302(5 liter), but only at 4000 RPM. Anything under 4000 RPM and it's only a 244(4 liter). The size of the cylinder bore and/or length of the stroke doesn't change.

I'm think about dropping the direct drive setup in favor of pulleys and a belt. Besides being more complicated and expensive, especially if I have to have custom parts fabricated. With direct what happens should the compressor seize? I really don't want that big motor ripping things apart. So by switching to a pulley setup you can build in a certain safety factor, should the compressor seize all you lose is a belt and it is easier to setup and most likely cheaper too.

However the bad side is that with pulleys, each pulley could be spinning at a different RPM depending on their size. So we're back to finding the correct motor for the job.

You guys have been a big help, keep it coming!!!

 

[bigtigexplorer]

Since I'm going to go with a pulley system, I crunched some numbers and came up with the table below. Assuming the compressor clutch pulley is 6 inches in diameter and the motor is spinning at 6000 RPM. It looks like I want to use a 3.25 inch pulley on the motor to spin the compressor at about 3250 RPM.

Would somebody mind reviewing my numbers? I'm pretty good with math but it never hurts to double check.

Thanks again

 

[Robb]

My math agrees with that.

Looking quickly at my Grainger book, you are looking at:
Browning AK64 (6" pitch dia w/ "A" belt)
Browning AK34 (3.2" pitch dia w/ "A" belt)

You could go with a variable pitch sheave if you wanted to fine tune it, but at 6000rpm, I wouldn't recommend it.

Another thing to keep in mind. An AK34 doesn't have much "belt to sheave" surface area (+/- 5"), and you could end up with a lot of slipping at that speed. A bigger sheave would be more preferable, but that would involve going to a larger comp sheave also, which I don't think you want to do. Of course, a 3450 motor would help this situation.

 

[bigtigexplorer]

The 6" pulley for the compressor is the stock clutch assembly. I got the compressor with clutch off a old LTD in the junkyard. I am my no means a mechanical engineer, I'm just pretty good with math and use trial by error. Could you explain what "sheave" is??

For the motor pulley, I've been looking at McMaster's - 6248K68 Die Cast Finished-Bore V-Belt Pulley 3.5" OD, 3.25" Pitch diameter, .75" bore

Also if somebody has extra time on their hands and wouldn't mind helping me search the net for better motor options, I would greatly appreciate it. So far I've been looking at the following specs for a motor.

winch motor
12 volt DC
2.5 - 5 HP
RPM ??????

Here is a link to a larger table for pulley selection based on the motor's RPM:
RPM Table

 

[Robb]

Sorry about that, sheave is just another word for pulley.

And oops on the compressor sheave sizing, I knew you were running a clutch, I just forgot . If it is 6" OD, just remember to take some off that size for your math. Pitch diameter is going to be what you want to work from.

I am unfamiliar with McMaster's line of sheaves. Browning is the most popular and trusted name in that field. I wouldn't run anything else, but that is just me.

No need for tables, just use this:
(drive sheave p.d x rpm = driven sheave p.d. x rpm)

Example:
Y * 6000 = 6 * 3250
Y = 3.25

And just another formula for ya (you said you liked math ), for when it is time to get a belt:
belt length = (2 x CL) + (1/2 x drive sheave circumference) + (1/2 x driven sheave circumference)
*CL = centerline distance, or the distance from the center of one shaft to the other
*circumference = pie(3.1417) x diameter
* this formula is an approximate

Example: (if you used 3.25" and 6" sheaves, with a CL of 8")
bl = (2 x 8) + (1/2 x 10.2) + (1/2 x 18.85)
bl = 16 + 5.1 + 9.4
bl = 30.5


I will do a little looking for a motor. Grainger didn't seem to carry anything to fit your needs, but there has to be one out there somewhere.