[Black Forest]

Hello, new member here! I live in Germany but come from Texas!

And yes you read it right. I want to build an electric mechanical cow. It should be electric of course. It will have tracks instead of wheels. The tracks stop the "cow" from bouncing so much in the sand in the riding arena.
Of course the tracks add much more complexity to the build as far as the needed torque and drain on the batteries but they are necessary. This "cow" should be about the size of a garden tractor and be remote controlled!

All the fabrication and machining is no problem for me. The CAD drawings are also no problem. The "problem" is all the electrickery involved. Not so much the remote control but the correct motors, batteries and controller, etc..
So that is why I am here.

It needs to have very good low end torque and the tracks need to be powered independently of each other so as to facilitate the tracks running in the opposite directions of each other. Think bulldozer, tank, excavator or Z-turn lawn mower.

If it would be advantageous to incorporate hydraulics in the build that would be no problem for me either.

Run time should be capable of minimum of 30 minutes.

What would all you experts recommend for the electric side of things?
Thanks in advance for any input. It should be interesting to say the least!

 

[john61ct]

I would think making it a bull rather than a cow would simplify things.

Unless the milk delivery function is essential to your use case.

 

[brian_]

If it would be advantageous to incorporate hydraulics in the build that would be no problem for me either.

I don't see any point in hydraulics.

Some people convert lawn and garden equipment which originally had an engine driving through a hydrostatic transmission by replacing the engine with a motor and still going through the original transmission, but that is usually done because they want to change as little as possible. That would not apply in this case.

Some people keep hydrostatic transmissions in skid-steer equipment (such as a "zero turn" mower) because they would rather buy one large motor and a simple controller than two smaller motors with suitable controllers set up for speed control. If you can do it properly (with two motors and no hydrostatic transmission), the result will be mechanically simpler and more efficient.

 

[brian_]

This "cow" should be about the size of a garden tractor and be remote controlled!

Although large, this is like the "battle robots" built for various competitions, so whatever they use might be a reasonable starting point.

There is also electric and remote-controlled industrial equipment, such as a skid-steer loaders, but some of that probably uses hydrostatic drives just because the manufacturer is set up to do that. There still might be some good examples to use for inspiration.

 

[brian_]

Think bulldozer, tank, excavator or Z-turn lawn mower.

Similar vehicles, including Argo-style ATVs and "zero-turn" mowers, come up for discussion occasionally in this forum, but the projects typically don't get built. The discussions might be of some use, but successful examples to copy are rare, although the second one below got further than most (they actually installed motors, and ran one):
Motor Selection Confusion with Mower Conversion
Zero Turn Radius Electric Riding Lawn Mower

Despite the "tank" controls in many video games, typical tanks actually steer with a steering wheel, not left and right sticks. In the ones that I have heard about, they also cannot maneuver like a skid-steer loader, since the tracks cannot move in opposite directions unless the tank first comes to a compete stop, then shifts to a different transmission mode that only rotates on the spot.

 

[brian_]

I want to build an electric mechanical cow. It should be electric of course. It will have tracks instead of wheels. The tracks stop the "cow" from bouncing so much in the sand in the riding arena.
...
It needs to have very good low end torque and the tracks need to be powered independently of each other so as to facilitate the tracks running in the opposite directions of each other.

I assume that as a "cow", it will not be ridden by anyone. Does it need to move quickly enough to be a challenge for something like a roping competition, or it is just for display?

 

[Black Forest]

I assume that as a "cow", it will not be ridden by anyone. Does it need to move quickly enough to be a challenge for something like a roping competition, or it is just for display?

It will not be necessary for it to reach actual roping speeds. If it could reach 20mph that would be enough.

 

[Black Forest]

Similar vehicles, including Argo-style ATVs and "zero-turn" mowers, come up for discussion occasionally in this forum, but the projects typically don't get built. The discussions might be of some use, but successful examples to copy are rare, although the second one below got further than most (they actually installed motors, and ran one):
Motor Selection Confusion with Mower Conversion
Zero Turn Radius Electric Riding Lawn Mower

Despite the "tank" controls in many video games, typical tanks actually steer with a steering wheel, not left and right sticks. In the ones that I have heard about, they also cannot maneuver like a skid-steer loader, since the tracks cannot move in opposite directions unless the tank first comes to a compete stop, then shifts to a different transmission mode that only rotates on the spot.

Brian I hear you about them not getting built. If I can come up with a feasible plan this will get built! I am like a pit bull when I decide to do something. Take a hold and don't let go! As an example I built a machine to help me shear my sheep. It takes all of the work out of shearing a sheep except the actual hand work of shearing. The machine picks up and manipulates the sheep while I actually hold the handpiece and shear the sheep. It is voice controlled also. I took a lot of ribbing and nay saying from people all over the globe. When you start talking about restraining sheep let me tell you.....the jokes start rolling in big time! In the end of the project my biggest nay sayers were the biggest fans of the project. The machine allows me to stand upright and not bend over to shear. Big body saver. Bad knees and back, etc..

 

[brian_]

Brian I hear you about them not getting built. If I can come up with a feasible plan this will get built!

I'm sure that it can be built... it is just the reality of do-it-yourself projects that it is easy to run out of money, time, or technical solutions. The skid-steer projects are relatively rare and fundamentally more complex than a typical EV, so I'm not surprised that none of them have been completed.

I just realized that my earlier search (starting with project that I had commented on) only went back to my most recent 500 posts. Before that, there was this one:
New zero-turn mower project - no hydrostats
It was still looking good 6 months ago, but there have been no updates since then.