New project - 4WD Articulated Tractor

Finally decided to stop messing about and make a proper project, a tractor....
Going for 4WD articulated, all hydraulic.

Bought 4 wheel motors and some steel and away I go. I'm buying the other bits as I get decent prices on them, steering valve should be coming this week, might look into pumps next week.

Pic 1 - rough chassis design
Pic 2 - hydraulic motor and mount plate
Pic 3 - rear axle unit

Here are some commercial versions of what you are planning

http://www.power-trac.com/

http://www.avanttecno.com/web/engpaasivu/engpaasivu.htm

Hate to bother the Inventor/Tinkerer IN Chief (ITIC) of NTT!

I do have a few questions when you have the time or the inclination to splain!

1. What type/output of hydraulic pump will you use?
2. How will you power the above pump?

It's a great project and wait anxiously on the progress!!

Mith,

Great stuff and a renewed science. Honestly, I don’t understand why most all tractors aren’t hydraulically propelled, steering braked and all wheel drive. With modern technology (and a basic and narrow minded ‘gripe’ of mine is) why more 4WD tractors don’t have all 4 wheels the same size.

If I understand your design and thinking you will have eliminated:
Brakes. (By diverting fluid pressure to the opposite port and feathering between forward and reverse)
Transmission. (AWD will eliminate front/rear differentials and 4WD ‘wind up’,
Clutch, Pressure Plate, throw-out bearing, pilot bearing and mechanical shift gate)

And all due to the fact you’ve selected a stationary engine and pump. I’m anxiously waiting for progress and hereby nominate you to the IMEA - Independent mechanical engineering award - (a fictitious award at level with the Nobel Peace Prize )

Mark

Mith said:

Finally decided to stop messing about and make a proper project,

Click to expand...

Yeah, all your other projects were trivial!
Mith, you are one of a kind! If you ever make it to this part of the earth, I have unlimited work for you, for room and board in return of course!
Bone

Dean, going to be using a twin fixed dispacement gear pump (2 sections, 1 for drive, the other for steering and accessories). 19cc/rev and 6.5cc/rev (16gpm and 5.5gpm).
Going to kick off with a 12HP which I already have to make sure it works (it'll be grossly underpowered) and look out for a cheap 20-30HPish diesel. I'll leave room for the diesel when I make it, so the change over wont be hard.


Mark, you've gotta assume there is some reason why there arent more articulated tractors about, the 'normal' design of tractors doesnt seem to be all that efficient.
I'll drop in a few check valves for braking, as soon as you let off the drive pedal it will be locked still. I'll probably put a damper on the pedal so you dont let off too fast and hurl yourself over the bonnet.
I'll plumb it so the front and rear axles are locked together, but as if there is an open diff on each axle, so they dont bind when turning. I might plumb it so you can select locked diffs on the axles.
In terms of the drive train, you shouldnt be able to break it, apart from breaking a wheel motor shaft there arent really any bits under meachanical load.

Bone, it might be a good idea for me to be near to someone who knows first aid

Cheers guys

Fantastic project....I can't wait for more pictures.

I'm with Bone....board and room, plus a mule to ride, and a big first aid kit...well what's still in it that I didn't already used.

Mith,
What size tires will it have?
Looks like an awesome "fun" project.
hugs, Brandi

I see you have the hinged pivot but you might do well to consider torsional articulation at that joint too. With your terrain I would strongly recommend it at this stage.

A couple of 40mm ID flange type pillow block bearings should be man enough for the job.

This is a cool project Mith, I admire your tenacity... Cant wait to follow THIS ONE!!! Now put down your computer and get back out to your workshop!!!

I second the IMEA award...!

q

Nica, sounds like a trip is in order

Brandi, 26" tyres is the biggest I can afford, but no reason I cant upgrade when I can. I'm building it big, so I can just upgrade parts when I can. The frame is 5x3x0.25" box.

Q, check the front axle, it'll pivot to allow for bumps. I wanted to keep the middle joint for steering only, the ones I have seen made to pivot more than 1 axis seem to break on occasion.

Now put down your computer and get back out to your workshop!!!

Click to expand...

Aye! I'll have more pics later, off to the mill to make some holes.

Thanks all

Made some big holes on the mill using the rotary table.
A little more machining and welding to finish the hubs.
My hydraulic steering bits. Bushes, 1 of the rams, and the valve.

Mith,

The hydrostatic cub cadets have a linkage that helps reduce the "thrown over the bonnet" effect.

I cant describe it very well and I dont have any pictures, but i bet a web search might give you some ideas. It has the linkage slide around in a spring loaded groove to absorb sudden cahnges in position.

Good luck and awesome project!

Mith,
Interesting project. Something like this always fascinates me as you can go off in many directions with it.
hugs, Brandi

Hi Mith

Kohler started taking orders for their new diesels 1 Feb., but I have a feeling you will be leaning more toward one of the Chinese knockoffs, if you're gonna drop in a new one. Used, I understand the VW diesels are pretty solid, and adapter plates are readily available. But you're gonna mill your own, I guess.

If I were a betting man, I'd put money down that you're also allowing room for a radiator?

If I remember correctly (Hah! ) Coop (at that other place) put in a US Govt. surplus 4 cyl gas engine in his articulated Cub Cadet. Or maybe it was a Case?

No, a twin Cub Cadet...CubZilla.

Ted...
...ain't unassuming...

Ted, I'm keeping an eye out for a Kubota diesel. Nice 3 cylinder maybe, they are dead common, just need to find a machine with one in with a bad trans or something. I'm set on a diesel as I want to run it on red diesel, which is nearly half the price of petrol.
I've found one to measure tomorrow, so I'll measure the length of the engine with the radiator etc and leave room for that on my machine.

Got the rear axle unit tacked together, and the parts for the front are done too.


Hung a wheel on, I need to order the tyres some time, might have to order 2 and wait to get the other 2, too expensive to buy 4 all at once....

I got both the front and rear axle units done now, and almost done the rear frame.
However, no pics as my camera phone has died. You'll have to make do with a pic of a big lathe from last week.

Hey Mith, I dont know if theres an Aldi near you but they have an offer coming up on Thursday 27th April. A 5 mega pixel camera for £40... My dad got one of these last year and it is a very good camera for the price.

http://www.aldi.co.uk/uk/html/offers/58_5771.htm

Thats a seriously attractive price considering the bits and bobs it comes with, alas, no Aldi nearby I know of.
I'm hoping a new charger will sort the problem, it wont take a charge from the current one. Probably one of the pins bent over or something, but its way to small to fix myself.

The frame is pretty much done, tacked, but together. I bought the tyres, and widened the rims to fit. Tried to get them seated today and decided it wasnt going to happen. Took them down to the tyre place, and he couldn't get them on either, (and he wasnt happy with the widened rims). So I ordered some tubes ($100) which I was trying to avoid having to do. I was really hoping to have it on its wheels today.
Anyway, it sure looked smaller on paper. Its a shade over 8' long, and a shade under 5' wide. I reckon it'll be 7' to the top of the roll bar.
I'm still tracking down an engine, thats becoming a bit of a frustration at the moment, I let 2 slip through my fingers. I'll find one eventually, but its really holding me up now.

Mith - I like your new camera! It's long over due!