Walking Tractor

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gromike

10 kW
Joined
Nov 3, 2022
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Last thing that I came up with here was a skid steer (or tank steer) cargo trike. That kinda got shotdown, but I'm still thinking about it.
Though there has been some evolution in my thinking. How about a two wheel walking tractor?
My first wife and I bought 5 acres of raw land, long time ago. I cleared the building site with a David Bradley walking tractor that was bought from a thrift store (Saint Vinnies on Lake Union). Maybe a horse and a half. That was back in the day of owner design/build permit, 10 bucks! That thing sure taught me about tractors.
So that got me thinking, why not make a battery electric two wheel tractor. I have the controllers and batteries, the wheels and tires are about $700, plus some iron.
Seems like a win, though I would need a plow and cultivators for this latest pipe dream.
 
Some stuff to think about:

--How much power does it actually take to dig in and plow? (size of motor(s), capability of controller and battery)

--How long does ti take to plow the total length of furrows you need? (capacity of battery)



A quick google shows anything from 15-170+ hp for plowing with an engine-powered tractor, depending on depth and type of soil. If that could be translated directly to electric (it probably can't) that would be 11.5kw minimum up to 127.5kw+ . If so, it sounds like quite a large and expensive project....Since plowing can be done with a single real horse (even just one human if you don't mind it being slower), then it ought to be possible with 1kw or less electric, but it would depend on the design and conditions, etc.

I don't know much about the technical needs for plowing (I rode on top of tractors and combines as a kid in farm country; that's as close as I got to plowing :lol:) so there's probably more leeway than that dependong on what you really want to do.
 
The David Bradley walking tractor was about 1 and 1/2 horsepower, and I'd say a half an hour was enough to plow a garden plot.
 
Well, the ewalking tractor has given much to think about. I'm planning on buying a couple of single sided motors from leaf. It's my pre-Trump2 Christmas present, so to speak.
There is a problem though. A tractor needs implements. I priced appropriate sized implements. A plow, a disc harrow, and a cultivator are around $2000! So I thought that with motors it would be best if they were repurposable. A 15kph wind would be great for a walking tractor, but not so great for any other dream. So, I'm leaning toward a 32kph, 20mph wind. Though, slower might be better for experimentation.
20 inch 48V 52V 1500W beach snow fat tire single side shaft motor wheel
This build, in my mind, is a steel platform with a motorwheel on the two opposite sides. The batteries and controller would be mounted in it, and I could bolt or weld any configuration I could think of to it.
I already have two of those Sarcos 21700 48v battery packs. and one of these controllers: https://www.amazon.com/gp/product/B0C7PZLN1Q/ref=ox_sc_act_title_4?smid=ADW5J3KOIOS7J&psc=1
It's a dumb controller but it rocks in a 500w DD bike.
I have a better than my first Harbor Freight wire feed welder, and a chop saw. What could go wrong?
 
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I really doubt a pair of 1500W Leaf motors can muster enough torque to do what you want, even if they have more than enough power to do it. Whatever their torque is in lbs-feet, that's pretty much how many lbs of pull force they can potentially make when fitted with 20" fat tires. But they'll only make near maximum torque in a pretty inefficient speed range, and continuous operation in that condition will overheat them.

Perhaps I overestimate how hard you have to drag on a plow or a harrow. I don't have any experience with them.
 
I agree that a slow wind is most desirable for a walking tractor, but if that didn't work I would want to repurpose the motors for some other use. So, I'm slow to pull the trigger on a slow wind motor.

I did quite a bit of plowing with a David Bradley walking tractor:
https://www.pinterest.com/pin/506373551854915066/
.
It plowed just fine, though on full throttle on it's couple of horsepower single cylinder engine. So 3000w of electric motor power should work, but yeah, for how long would the motors pull before overheating?

I'll think it all over for another day.
 
A slow motor wind gives better torque per amp, but doesn't increase the maximum available torque at all. There's a certain amps x armature turns value that results in saturation torque, and you don't get more than that without burning your motor down. Making only the motor's saturation torque results in a heavy heat load that you can't sustain for long.

Short version: Every winding gives off the same heat to produce the same torque; so there's a given, as yet undetermined, torque value that you can maintain indefinitely. You have to trade volts against amps to get there depending on the winding you use.

If your tractor is built to run on a lower voltage than whatever other thing you want to run at 20 mph with the same motors, then you can (within limits) develop the motors' maximum continuous torque at a wheel speed that makes more sense for a tractor. Whether that's enough to continuously drag a soil breaker is an open question.

If I remember correctly, Leaf 1500W armature slots can hold up to 66 strands of magnet wire. So 3T, 6T, 11T have optimum copper fill. 5T and 13T are the next best thing.
 
gromike said:
So 3000w of electric motor power should work, but yeah, for how long would the motors pull before overheating?
Click to expand...
forever if you gear them correctly and provide the required cooling

see the ebikes.ca motor simulator
 
amberwolf said:
forever if you gear them correctly and provide the required cooling.
Click to expand...
Thanks amberwolf.
After looking at the Grin motor simulator it looks like a direct drive motor would have a tough time at walking speed. Then, I guess it would be a geared motor. Need to search for an ag motor wheel. I've seen them before, but know not where.
 
even a geared hubmotor is still meant for higher speeds, so the gearing you're probably looking for would be a gearbox or other reduction between your motor (of any kind) and drivetrain. you can use the simulator to find out the ratio required

there have been some hubmtoors made for walking speed, which have been discussed in various other slow-speed device threads.
 
Use a non hub motor of suitable power and use gear reduction toamplify the torque….
In the same way that Bradley tractor did !
Infact , why not just find an old Bradley (or similar..Howard ), and just convert the motor to electric drive ?
 
Hillhater said:
Use a non hub motor of suitable power and use gear reduction toamplify the torque….
In the same way that Bradley tractor did !
Infact , why not just find an old Bradley (or similar..Howard ), and just convert the motor to electric drive ?
Click to expand...
I'm thinking a battery motor wheel could revolutionize the two wheeled walking tractor.
But it is such a low hanging fruit that it has to have already been done, somewhere in Asia I would guess.
 
I don't think you would really want to stick the batteries in the motor where it gets really hot so the batteries will age faster and/or be damaged. it also means you are forced to have a really tiny battery unless you make a huge motor casing to fit them in.

presumably you'd also have the ocntroller in there since otherwise you have to pass not only the motor wires out of the motor to it but also the battery wires, and wiht the controller in there it wil get even hotter and have even less room for batteries.

the only system i know for sure that was commercisally made like that was the copenhagen wheel, which took years to get to market, even longer to actually begin to get delivered to those that ordered them, and went away really quick after that. there's a recent thread about some people with problems getting the battery to charge, probably because of abnormally fast aging due to the heat trapped in there with them.
 
What I meant was a battery "powered" motor wheel, not a combined motor/battery/controller motor wheel. So, my idea is much more basic. My searching for a powered wheel went in the direction of agriculture robot motor wheel. I did find a suitable motor wheel, albeit at a less than ideal wheel diameter. The implements would need to be downsized from a David Bradley tractor, which is getting to the ridiculous. But if it was remotely operated you could sit in a lawn chair and cultivate your garden plot.

With the trump2 era upon us, well, it's stirs my latent survivalist instinct. It's not like a 70 something year-old-guy is going to survive a civilizational collapse for long. Maybe it's just therapy to build (or plan) the tools one would need.
My reaction to his first administration caused me to build an 800a 12v battery bank, topped by a 2500w inverter. With limited knowledge that cost way more than it should have, but I do have a great power source for my Kweld.
 
gromike said:
What I meant was a battery "powered" motor wheel, not a combined motor/battery/controller motor wheel.
Click to expand...
well, generally on this forum they would *all* be battery powered. very few people here (probably anywhere) use generators or other power sources to run their motor wheels***, so...it's generally assumed when discussing an ev of any kind here on es that it will be battery powered. ;)

so using the unusual term "battery motor wheel" is more likely to make people think of the rare systems that actually put the battery (and controller) in the motor wheel itself.


***even the ones that do usually still have a battery that's actually powering the motor wheel, and just charge or keep topped off that battery via the other power source (solar, generator, etc).
 
Full walking speed ahead on the walking tractor plow build. I found a David Bradley walking tractor plow at a good price, and local too! With a bit of luck I'll be plowing this spring :) .

I'm using two of these wheels:
KK161.jpg


4.00-8 tractor tire single shaft 16 inch heavy load geared hub motor
 
Got a plow!
Under ninety bucks, including the tax and a couple of gallons of diesel to do the hundred mile round trip to pick it up.
Muy impotante is the plow! The rational is to build a battery electric walking tractor plow. I bought it a second-hand building stuff store in Seattle. It was a bargain at sixty-five dollars. It's in perfect condition, outside of a de rigueur of rust. At seventy-plus years old she's a beauty. The price was great, but I was probably the only person in western Washington looking to buy a David Bradley plow.
PXL_20241204_000703643.jpg

The motor wheels I bought have an outside diameter a bit over half of the David Bradley's wheels. Each wheel is rated for 500w, peak 800w. The early David Bradley was about 1 and 1/2 hp at the motor. I assume less at the wheels. So, the power should be basically equivalent. I hope.
 
I have been cruising the web looking for two wheel electric tractors. I have found a couple that are more of a commercial industrial bent, and a few that were an experimental repower of existing gassers.
Seems like there is no tank steer two wheel small ag tractor visible on the interwebs.
So, that makes me think that a two motor wheeled garden tractor is a good place to experiment. Kind of like where you early ebike guys were at twenty years ago.
 
If you have trouble getting satisfying performance ..
Your low rpm & high torque / power operation is a good theoretical fit for a Transverse flux motor design .. they excel at being able to do (direct drive without transmission) very low RPM with high torque / power / and in that operating state still have good motor energy efficiency.

Because they are not as mass produced as other motor flux designs , they are unfortunately harder to find used or low cost.

Maybe there are others out there .. but the only company I know of regularly making & selling transverse flux motors is ETM
etmpower.com

Technology » Electric Torque Machines %

etmpower.com etmpower.com
 
gromike said:
I have been cruising the web looking for two wheel electric tractors
Click to expand...
Classic 2-wheel walking tractors are very popular in Europe (Italy especially). Check into a used BCS, Ferrari, Goldoni, Bertolini, etc. and maybe re-power it(???). Then you have the whole array of modern implements available for it. I used to drive a Ferrari every day. A lot of strange looks when driving into town in rural Wisconsin.)

trailer_src_2.1.jpg
 
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