PTO Welder

[CFHartman]

I have a very old AC welder and generator. I'm consedering scraping the engine and trying to hook the welder generator up to the PTO on my tractor. Can anyone tell me were I could get a gear reducer with a 540 input and 3600 output. That's almost a 7 to 1 ratio.

 

[Squeak n Itch]

This is a great question. I would think this same gear setup, although probably more accurately a gear increaser, would benefit those seeking power for pumps, compressors, generators and other farm type accessories that could be powered by a tractor. An even higher ratio, say 10:1 could permit us to use lower tractor RPM (and therefore fuel) and power accessories requiring 10HP or less. If not available "off-the-shelf" perhaps this is a good business opportunity.

 

[Treemonkey1000]

You could get the same affect using V-belts with pulleys. I would use a dual pulley. Then engineer the frame to hold the welder or what ever device you want in line with the PTO. There are gearing reducers or increasers out there. The rear end from a car or truck might be a choice or even a small tranny from a vehicle. We used a truck tranny as a speed reducer on the log carriage for my Uncles Sawmill

 

[joe48]

The DIY method is great and easily doable several ways.
1. Check industrial supply catalogs like Grainger or Johnston, both have numerous gear boxes to reduce or speed up and change direction of rotation,(CCW to CW). Also do an internet search for gear reducers,etc. or go to the nearest large city phone book and look for gears etc. They only issue is cost, but you could find almost anything you need.

2. The auto/truck trans solution. There are numerous car/truck trans that have over drive ratios in 5th gear (some 4th too) that may range from 0.6 to 0.7. ie: 540rpm / 0.66 ratio = 806rpm 3600 / 806 = 4.5 ratio
so: you need a 13.5" pulley on the trans if you have a 3" pulley on the generator input shaft. (3" x 4.5 = 13.5") The pulley and belt eliminate alignment issues. Also you must determine your rotational directions and if you need to reverse directions ,which is possible. The input and output will rotate same direction CCW or CW.
The other option with a car trans is if you are using it on alimited basis only a few hours at a time then you can use reverse gear. Most trans' are not designed for constant running in reverse, but will still last quite a while. Another option is switch the input and output, put the power in the tailshaft and drive the generator from the engine side of trans. Now you have a bunch of overdrive gear choices. The downside is most modern trans gears are not as hard on the back side of the teeth as they are on the front side where they are designed to run. Old truck trans fron 50 + 60's are usually hardened the same on both sides so they can be run backwards a long time. This option would be attractive as you can select different gears to adjust engine speeds to loads.
3. Set up a series of pulleys and jack shafts to reach the desired speed of out put. A single jack shaft from tractor to generator would need this.
3600rpm / 540rpm = 6.66 ratio So; a 3" pulley on generator would need a 20" pulley on the tractor shaft. If the tractor turns CCW and the gen is CW then turn the generator around so the jackshaft runs past generator which is now facing backwards, so jackshaft will be turning CCW and driving gen shaft CCW.
Hope this helps , this is an easy fun project that has been done with every option I gave many times over.
Good luck and include pictures.

 

[Mickey_Fx]

Seems like what you are looking for is the same kind gearbox being used on PTO gensets. Don't know if the various CO's that build then genset make their own drives or are purchased from a separate Co. Not sure how easy they'd be to hooking up but they are the correct ratio.

 

[RWolf]

There's still one question that needs to be answered. How big is the generator/welder. i.e. what size motor drives it right now? What I'm thinking about is if the welder/generator currently uses a 10hp motor as an example after you create your gearbox to run the welder/generator at it's appropriate speed how much hp from the tractor are you going to need. My math isn't that great but I'd think that at a 4.5 to 1 ratio you'd need at least 45hp using the example I gave. Those of you that are better at this than myself could elaborate.

Good luck on the project as it sounds very interesting.

 

[barneyrb]

I agree this could be done with drive belts, but the way that I would do this is to use a double reduction system. One belt (or set of belts) for 1/2 the reduction reuired. For instance your first reduction could be 2.7:1 and your second reduction 2.5:1 for a total reduction of 6.75:1. This would require a short jackshaft of some kind. Also like RWolf said above, if your gen requires 15hp to run now (at 3600rpm) your jackshaft or gear reduction system would require 101.25hp to run now. Another option is to use the high speed of your PTO to reduce gear reduction, but it will still require more hp than the genset engine.

 

[joe48]

Guys! Don't mix apples and oranges, the ratios discussed whether 4.5:1 or 7.5: 1 are all speed to speed relationships. RPM to RPM.

Now if you want to calculate how many horsepower is required to run this generator we need to know the KILOWATT rating. Then it is a simple calculation to find required HP, using a standard rule of thumb factor.
All calculations assume that the generator is operating at FULL electric load.

For direct drive; engine to generator requires at least 1.7hp : Kilowatt (1000 watts) (this includes a power transmission loss factor).
ie; 5.5KW x1.7 = 9.35 or 5500watt needs a 10hp engine.
ie; 20KW x 1.7 = 34 or 20,000watts needs a 34hp engine.

Now if using PTO and gear box or jackshafts we need to add in an additional power loss factor of 10 to 20% for transmission losses, so to make it simple lets use 2.0 as our multiplier.
ie; 5.5KW x 2.0 = 11hp at the PTO
ie; 20KW x 2.0 = 40hp at the PTO

ok ,get r done and send pics.

 

[CFHartman]

Thanks for all the replys to this post. Do to some of the replys I did some checking and found that it is a 10HP Kohler engine and is rated at 7.5 KW @3600. After looking the engine over I think I'm going to try and get the engine running. I think I can still order parts for this engine.
Thanks All
Charlie

 

[Iplayfarmer]

Guys! Don't mix apples and oranges, the ratios discussed whether 4.5:1 or 7.5: 1 are all speed to speed relationships. RPM to RPM.

Now if you want to calculate how many horsepower is required to run this generator we need to know the KILOWATT rating. Then it is a simple calculation to find required HP, using a standard rule of thumb factor.
All calculations assume that the generator is operating at FULL electric load.

For direct drive; engine to generator requires at least 1.7hp : Kilowatt (1000 watts) (this includes a power transmission loss factor).
ie; 5.5KW x1.7 = 9.35 or 5500watt needs a 10hp engine.
ie; 20KW x 1.7 = 34 or 20,000watts needs a 34hp engine.

Now if using PTO and gear box or jackshafts we need to add in an additional power loss factor of 10 to 20% for transmission losses, so to make it simple lets use 2.0 as our multiplier.
ie; 5.5KW x 2.0 = 11hp at the PTO
ie; 20KW x 2.0 = 40hp at the PTO

ok ,get r done and send pics.

Thanks for posting this. I was so lost as to where everyone was coming up with needing 100 Hp tractors to run a 3600 watt genny.

You're right, though. Changing the gear ratios won't change the HP needed except for maybe the transmission power loss. You need more torque, but at the slower speed (540 vs. 3600 rpm) the horsepower is about the same.