Open Source Walk Behind Tractor ?
Posted April 10, 2014 - 09:21 AM
So my question about the design of this tractor is mainly about the drive system setup? I don't mind a simple differential and chain drive system with a clutch. Id like it to stay as simple to build as possible. The frame and chassis will be the simplest portion of this project to build from steel.Id like 18" implement tires on it. The great thing about these tractors is you don't need a huge motor to drive it..a 13 hp 420cc gas engine clone from harbor freight would do. I would probably also need a gear box to gear it down of course. I need some help figuring out what the best way to design this tractor would be if you were looking to source the parts from some place like Surplus Center. Any assistance would be appreciated.
- Jehtro and boyscout862 have said thanks
Posted April 10, 2014 - 09:46 AM
- trowel said thank you
Posted April 10, 2014 - 10:04 AM
I'm wondering if Rick has identified the reason why they went with a larger more complicated tractor. Working 10 acres by hand with a big walk behind wouldn't be an easy task.
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Posted April 10, 2014 - 10:58 AM
I don't know if I really agree with the Marcin project, its all good if you have a complete weld / machine shop available to you. But if you did , you probably won't be building one. Also the designs I don't think would fair well in our climate up here.
Posted April 10, 2014 - 11:04 AM
Well in the 30's, Sears sold the Handiman, and proclaimed the tractor was for farms of 5 to 20 acres. I think the time factor in the modern age, has gotten everyone to thinking bigger , better, faster. Sometimes this isn't the case. You can plow a lot of ground in a day with a walk-behind model. Mostly I would guess it would boil down to whether or not you think your up to the walking. I personally farmed 12 acres with almost all walking tractors. The only work I didn't do was to plow, and for that I used a small Ford tractor.
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Posted April 10, 2014 - 11:48 AM
So if anyone could recommend the simplest and best way to build a drive system regarding this tractor I would appreciate it. I am not here to debate whether I should buy a larger tractor. I don't want one, the cost to maintain and dangers of using them on hilly ground is too high for me. From my point of view I would much rather keep the project as open source as possible that way if I need a new part I can easily find it in a surplus center catalog.
My idea is to weld a simple square frame chassis up with a longer handle system like the asian two wheeled variety. I will also have a braking system built in. I assume a differential axle setup with a sprocket and chain to the motor/ clutch will be sufficient for my needs. I just would like some brainstorming to understand what this build encompasses.
Northern tool and surplus center have an assortment of axle and clutch options. I can also use a go cart brake system to add some stopping power. There is a local gearbox company in my town that could probably have a specific gearbox to gear down my build when I need it.
Edited by GT_hacker, April 10, 2014 - 12:17 PM.
Posted April 10, 2014 - 12:26 PM
Well, for the differential, they sell go-cart diffs different places, but who knows how much power that will accommodate. You will have to make a decision on your wheel diameter before you can really nail down gear reduction, a 16 inch diameter wheel will not travel as far during one rotation as a 26 inch diameter wheel. I'd at least make my first reduction off the engine via a belt, belts and pulleys are cheap. Final reduction could be via a chain and sprocket setup. Personally, I think your biggest challenge will be getting a differential that will hold up to the power and demands you are placing on it.
For ease of design and robustness, I'd look at a single wheel drive set-up. I know Gravely started with a single wheel walking plow. Also, I'd look closely at the David Bradley "Tri-Trac" design, which had a single rear wheel and dual front wheels for stability and steering. Redesign that a bit around a 26 x12 x12 wheel, or an ATV 25 x 10 x 12, put the operator low to the ground for added stability, and the outrigger axle out front can sit up kind of high for crop clearance.
I think even if you insist that you don't want to ride, yet still be able to pull a cart, that a single wheel tractor could be designed to be incorporated to drive a trailer if you started from the ground up.
Keep us posted on your progress
- IamSherwood said thank you
Posted April 10, 2014 - 12:43 PM
Also, 13 Hp is a LOT of power for a small 2 wheel tractor, you won't use that much. Also, I decided that if you are set on using 2 wheels, you might actually be better off with two engines, and two drive trains, no complicated differential then. Plus, that would give you some differential type action, yet still keep both tires powered so you are less likely to get stuck.
And while you said you want belts and pulleys, you might want to think about how the zero turn mowers work. Individual hydraulic motors with the engine driving a single pump. Again, no need for an open diff axle.
Another suggestion would be to look around at some of the electric conversions which have been documented on this site. Pack a couple of batteries and a twin electric motor set-up with twin controllers onto a two wheel setup and you've got plenty of tractive weight to use. If you need to run the tractor all day, use a small thrifty gas engine to drive an alternator that can charge the batteries while you are out in the field.
Posted April 10, 2014 - 01:17 PM
If your familiar with the Wheel Horse tractors from the late 60s thru 70s , I could easily see removing the front axle and shortening the frame so the engine is where the dash and battery box would be. The rest is easy. An 8 hp Kohler engine would be great.
Posted April 10, 2014 - 01:51 PM
Thanks for your input. I am not totally set on the single axle and chain and sprocket setup. I really like to the hydraulic setup idea and the electric drive motors with alternator assist from a small engine. These are the reasons I came to this forum. I need some pros and cons to the whole idea. Ill keep everyone updated. Depending on the power delivery system I use will decide my tire and wheel size. I have a set of 2 extra 16" wheels for my nh lb620 backhoe that I could use. They are a bit bigger than I want but well see.
At the moment I really like the hydraulic route. I wouldn't need any overkill horsepower and the torque should be good for my application.
Posted April 10, 2014 - 02:49 PM
Have you thought about one of the Gravely 2wheel tractors instead of the DB. They are very capable machines and since they are a bit newer and were used in commercial applications it may be easier to get parts. If you are using surplus parts to DIY you will need to buy spares to ensure parts availability. Designing a 2 wheel tractor that will perform as well as established designs is not a trivial task and could end up taking a long time to get dialled in.
- trowel said thank you
Posted April 10, 2014 - 02:52 PM
Posted April 10, 2014 - 03:01 PM
Google the asian walking tractors and youll see what I mean. There is a difference in the design of those and the walking tractors of bcs and rapid
Posted April 10, 2014 - 04:06 PM
- trowel said thank you