Building small tractor

Pulse · Jan 21, 2017

Hello,

New here, In the process or designing and building a small utility type tractor. Im considering the Kohler ELH775 30 hp gasoline engine since its liquid cooled for in cab heat.

My current road block in the transmission, I spoke with comet clutching and they have a perfect cvt drive and driven pulley for me, I just need to find a transmission? Im looking for a low speed transmission with at least forward/neutral/reverse. anything more than that would be a bonus. I only want the machine to do about 15mph but I can gear down with the sprockets if necessary.

Does anyone know of anything that is available that would work for me?

Thanks in advance,

bcp · Jan 21, 2017

Inboard boat gearbox, maybe.

inboard boat gearbox - Google Search

M-151 transmission: front and rear output shafts

m151 transmission - Google Search

Bruce

Pulse · Jan 21, 2017

Thanks for the suggestion bcp,

I contacted ZF about their marine gearboxes, they said they are not designed to withstand the torque associated with a wheeled drive train

I also thought that may be the perfect solution, has anyone else used a marine gearbox in this sort of application?

bcp · Jan 21, 2017

Others that come to mind are golf cart, motorcycle, and ATV transmissions. Or hydraulic pump-motor drive.

Bruce

airbiscuit · Jan 21, 2017

If you are looking to buy all new components, isn't this going to cost more than buying a tractor? I think it's cool to build your own. It would be helpful to know its intended purpose, how you will use it. What are you going ti use for rear differential, frame, anticipated tire sizes, etc.?

I'm asking because I'm wondering about doing something about re-powering an old Allis Chalmers B of similar. Maybe Suzuki Samurai parts would work?

Interesting project. Will be fun to see how it comes together.

sixdogs · Jan 22, 2017

Do some searches in on this site using the Google box in the upper right. There are some very talented people here that have built tractors better than a factory could.

4570Man · Jan 22, 2017

How about hydraulics like a skid steer. The biggest downfall is $. A more budget friendly solution would be an automotive manual transmission with gear reduction in front of it. Or you could use duel 4 speeds which doubles your gear reduction.

davedj1 · Jan 22, 2017

I thought by definition a CVT was a transmission?
I would look into finding a world class T-5 transmission, not too big or bulky. Or any older 4/5 speed transmission.
Belt drive the transmission then you can have a tensioner to act as a clutch for changing gears.

Travelover · Jan 22, 2017

It used to be common to make your own tractor, or at least off road buggy, out of old cars. Back then two manual transmissions would be put in series, giving you tremendous gear reduction and fast speeds if you wanted it. You need to visit a good pick-your-own-parts junk yard to find reasonably priced parts.

Pulse · Jan 28, 2017

airbiscuit said:
If you are looking to buy all new components, isn't this going to cost more than buying a tractor? I think it's cool to build your own. It would be helpful to know its intended purpose, how you will use it. What are you going ti use for rear differential, frame, anticipated tire sizes, etc.?

I'm asking because I'm wondering about doing something about re-powering an old Allis Chalmers B of similar. Maybe Suzuki Samurai parts would work?

Interesting project. Will be fun to see how it comes together.

Im building a 8x8 articulating mini forwarder, the only ones you can purchase are in Europe and are very expensive, i believe i can build it far cheaper.

Pulse · Jan 28, 2017

Ive found RPM gearbox, which is a F/N/R gearbox, Im thinking i will need multiple speeds to maximise the torque while still being able to travel at a reasonable speed empty

My highest gear would only need to do about ~20 mph, and the lowest would need to be around walking speed or so. If i use a cvt, the driven cvt with the engine @ 3600 rpm would be 4750 rpm, Im thinking I will need at least 15:1 ratio to get nearly what i need?

There is room in the machine for a little more gearing down, but not a whole lot. The tires will be 20" Carlisle super lugs

Pulse · Jan 28, 2017

sixdogs said:
Do some searches in on this site using the Google box in the upper right. There are some very talented people here that have built tractors better than a factory could.

I've searched to the end of the internet, been banging my head trying to find something that will work for ages...

Pulse · Jan 28, 2017

4570Man said:
How about hydraulics like a skid steer. The biggest downfall is $. A more budget friendly solution would be an automotive manual transmission with gear reduction in front of it. Or you could use duel 4 speeds which doubles your gear reduction.

Hydraulics are still on the table as an option, Hydraulics arent as mannerly as a mechanical drive though. We have Kubota rtvs at work which are hydro static drive, guys hate them since they stop as soon as you release the throttle

Pulse · Jan 28, 2017

davedj1 said:
I thought by definition a CVT was a transmission?
I would look into finding a world class T-5 transmission, not too big or bulky. Or any older 4/5 speed transmission.
Belt drive the transmission then you can have a tensioner to act as a clutch for changing gears.

Cvt is somewhat of a transmission, only problem is you are limited to the variation of the cvt, Cvts do not allow you to reverse or multiply as much torque as a transmission. A 3 or 4 speed transmission with a cvt as a clutch may be the solution if i could find one. I do not wanna get into using old/scrap parts, I would like it to be all new and have the ability to replicate it.

Pulse · Jan 28, 2017

Travelover said:
It used to be common to make your own tractor, or at least off road buggy, out of old cars. Back then two manual transmissions would be put in series, giving you tremendous gear reduction and fast speeds if you wanted it. You need to visit a good pick-your-own-parts junk yard to find reasonably priced parts.

Ideally I would like to have a sequential transmission setup like what you find on a honda foreman 500cc atv. those are about as durable as they get, i just cant find anything like it! Im also considering using a kubota 902d for and engine instead of the kohler.

airbiscuit · Jan 28, 2017

Pulse said:
Im building a 8x8 articulating mini forwarder, the only ones you can purchase are in Europe and are very expensive, i believe i can build it far cheaper.

Might components salvaged from a forklift work? If you are building a forwarder, you will want robust components.

airbiscuit · Jan 28, 2017

Pulse said:
Im building a 8x8 articulating mini forwarder, the only ones you can purchase are in Europe and are very expensive, i believe i can build it far cheaper.

So, you are looking to build something like this?

D2Cat · Jan 28, 2017

Pulse said:
Hydraulics are still on the table as an option, Hydraulics arent as mannerly as a mechanical drive though. We have Kubota rtvs at work which are hydro static drive, guys hate them since they stop as soon as you release the throttle

I'm pretty sure there is a different valve you can put on your RTV to eliminate the sudden stop. Might check with your dealer.