[sameh4]

I pulled an electric motor, complete with its gear box and electronic brake from a golden mobility scooter, which I found from Facebook Marketplace. I tested it and it seems to work fine, rotates in both directions.

The label on the motor is torn but the part number I found shows that it's an ASI Technologies Part number 10517, which leads me to believe it's this motor.

The riding mower I am using is the John Deere RX73. It was free from next door neighbor. The current engine is 9HP Kawasaki 290cc, it runs OK, it smokes a bit but it does run and mower moves fine, and deck engages.

This is my first conversion. My education and work is in software engineering and robotics, so I am probably one or two notches past newbie but not very far.

Looking online at previous examples of mower conversions, they all recommend to use a separate motor for the mower deck, which makes perfect sense. So then the scooter motor would just have to drive the tractor.

I have many, many questions but I'll start with just a couple:

1. What calculations can I do to have an idea of whether this motor will be powerful enough to drive the mower. Based on the datasheet, I see that at Heavy load, it can produce 58 ft-lbs of force, with 114 RPM's, so does that mean it only has (58 * 114) / 5252 = 1.25 HP? Will that be enough to drive the mower (without the deck)?

2. I have not yet done the exact measurement, but it looks like the transaxle from the gear box (meaning the distance between the wheels on the scooter) is shorter than the width between the two wheels on the mower. I don't have welding equipment but I have used jb weld epoxy many times. Assuming it really is shorter, what are my options?

Thanks in advance!
Sameh

 

[cricketo]

1. Yes
2. You either have to weld, or machine the extensions. If you were really lucky and diameter of the two axles matched, then you could extend using seamless pipe, cross drill and pin. I doubt you're that lucky. Get yourself a Lincoln "buzzbox" AC welder for $100 on Craigslist and start practicing.

 

[brian_]

1. What calculations can I do to have an idea of whether this motor will be powerful enough to drive the mower. Based on the datasheet, I see that at Heavy load, it can produce 58 ft-lbs of force, with 114 RPM's, so does that mean it only has (58 * 114) / 5252 = 1.25 HP?

Yes, that product of the torque and speed is only 1.25 HP. For confirmation, the spec sheets lists the output power under those conditions as 942 watts; a horsepower is 746 watts so that spec is 942 W / 746 W/HP = 1.26 HP.

Will that be enough to drive the mower (without the deck)?

It sounds marginal to me, especially considering that it has to drive the weight of a person plus substantial battery across turf - scooters usually run only on hard surfaces, without cargo.

I think a similar axle with mounted electric motor from a golf cart would likely be more suitable. It would also be easier to narrow the golf cart axle than the widen the scooter axle, but I realize that the scooter axle is what's available.

 

[sameh4]

Yes, that product of the torque and speed is only 1.25 HP. For confirmation, the spec sheets lists the output power under those conditions as 942 watts; a horsepower is 746 watts so that spec is 942 W / 746 W/HP = 1.26 HP.

Thank you very much for the confirmation and clarification, exactly what I was looking for!

It sounds marginal to me, especially considering that it has to drive the weight of a person plus substantial battery across turf - scooters usually run only on hard surfaces, without cargo.

The intent behind this project is to autonomy, but you're making an excellent point.

I think a similar axle with mounted electric motor from a golf cart would likely be more suitable. It would also be easier to narrow the golf cart axle than the widen the scooter axle, but I realize that the scooter axle is what's available.

It's worth looking into it. I maybe able to find a junked Golf cart just like I found the Junked scooter.

Thanks again!

 

[MattsAwesomeStuff]

At first I thought you were going to attach a blade to a functional mobility scooter, and you had my new favorite project.

Instead... w op w op (apparently a slur that gets censored). You're just using mobility scooter motors to power a blade.

Even a small lawnmower, with now power drive, is at least a few horsepower, no?

It's probably too small is my guess.

That said, you can probably overvolt it and with some added cooling fans or a scrap CPU cooling pipe thingy, I dunno, maybe it'll be fine. The community regularly feeds 120+ volts to 48v forklift motors to squeeze more power out of them. I would do something similar here. Good thing is you don't really need speed control for the mower, just full speed and let 'er rip. 1.25hp for drive is certainly plenty. It'd get you up to 50km/h 30mph if you wanted it to, all day every day.

Seems like the kind of project that's more fun to goof off with and get used to taking stuff apart and putting it back together, than necessarily the need to end up with a good finished product. If so, full speed ahead. It'll either work, or it'll be underpowered. No big deal.

Your admission cost is to take lots of pics, share your failures, and let us know if it worked out at all.

 

[sameh4]

It's probably too small is my guess.

After reading several posts from you on this forum, I've learned your guesses are pretty accurate.

Seems like the kind of project that's more fun to goof off with and get used to taking stuff apart and putting it back together, than necessarily the need to end up with a good finished product. If so, full speed ahead. It'll either work, or it'll be underpowered. No big deal.

While I agree that it is a good learning project, and I could potentially end up with a nice platform for testing out autonomous software (as opposed to testing in simulator), I don't want to spend heaps of time if I am going to have to junk it later anyways.

What would be your suggestion in order to avoid this? Use a Golf Kart motor as @brian_ suggested? Would you suggest something else?

I have been thinking about the Golf Kart motor idea. The problem there is I don't have a hitch or a truck, so I can't get a junked one home and pull the motor then get rid of the scraps. I'd have to find a Gold Kart "junkyard" and ask them if they'll let me pull out the motor there. A quick look on ebay shows some pretty big price tags

What are your guys thoughts about all this? What would you do?

 

[Electric Land Cruiser]

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.

He used an Ardupilot autopilot and FPV stuff and could plow or mow from his big screen TV. He never did get it working autonomously. Sensors and Ardupilot is a lot better now than it was back then 2015-2016.

Video of plowbot:

 

[sameh4]

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.

It's funny you say this because that was exactly my initial intent when I got the scooter motor. But then I saw my next door neighbor putting the riding mower into his truck, so I took it.

I think I'll stick with the snow thrower, and once that's finished, I'll get back to the riding mower. It's pretty small and does not take too much space in the garage

 

[brian_]

Instead...
You're just using mobility scooter motors to power a blade.

Even a small lawnmower, with now power drive, is at least a few horsepower, no?

Yes, much more than one kilowatt is needed, but most of the power goes into turning the blade, which will have a separate motor in this case. The mobility scooter motor is not to power a blade, it is only to propel the machine.

 

[brian_]

The intent behind this project is to autonomy, but you're making an excellent point.

If you don't need it to be ridden by an operator, even at an early stage, that radically changes the requirements.

 

[brian_]

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.

The ride-on is too heavy for the scooter powertrain with an operator, but might be okay as an autonomous (or remote-controlled) vehicle. The advantages that I see of a small ride-on over a walk-behind are that it has a larger deck (so faster mowing) than typical walk-behind (the John Deere RX73 has a 30-inch deck), and that it has an easy place to mount a battery pack... but the scooter motor might still be inadequate.

 

[sameh4]

If you don't need it to be ridden by an operator, even at an early stage, that radically changes the requirements.

Thinking more about this: An average scooter rider is probably 180 to 220 lbs; give or take. Then there's the weight of the scooter itself, which is no less than 75 to 100 lbs. So at peak, we're probably talking 350 lbs?

The riding mower on its own weighs 345 lbs; I looked it up on the spec sheet, then there's probably another 50 lbs for the other batteries and the motor for the deck.

Now I could take off the deck and just make this project about having an autonomous vehicle testing platform. And then in the future change out the motor and transaxle to a more powerful one when I have it. That's a good option I believe

 

[sameh4]

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain. He used a walk-behind mower deck and it was well sized. I don't think a ride-on mower deck would work, too heavy.

He used an Ardupilot autopilot and FPV stuff and could plow or mow from his big screen TV. He never did get it working autonomously. Sensors and Ardupilot is a lot better now than it was back then 2015-2016.

Video of plowbot:

@brian_ The RC mower/plowbot in this video shows a trike with rear steering. In your option, what are the disadvantages to this approach.

On the positive side: I can see why you would want the front of the robot to have the most weight to power through the snow.

On the negative side: can't think of much, just intuitively seems wrong, but that could be lack of experience.

 

[brian_]

The riding mower on its own weights 345 lbs; I looked it up on the specks sheets, then there's probably another 50 lbs for the other batteries and the motor for the deck.

Right, but that includes the engine and transmission.

 

[sameh4]

Right, but that includes the engine and transmission.

Right! I just logged in to say that.

 

[sameh4]

Thanks for your help everyone! I plan to remove the deck, engine, transmission, and attach the scooter motor.

If I am successful then at the very least I will have a platform for testing autonomous software.

If not I am sure I will learn many lessons hopefully.

I think what I will do is start a new thread to track progress and other other questions there.

Any suggestions on which subforum?

Thanks again!

 

[brian_]

@brian_ The RC mower/plowbot in this video shows a trike with rear steering. In your option, what are the disadvantages to this approach.

On the positive side: I can see why you would want the front of the robot to have the most weight to power through the snow.

On the negative side: can't think of much, just intuitively seems wrong, but that could be lack of experience.

I agree that if the implement is hanging off the front (as a mower deck can be and a plow usually is), then it makes sense to put the drive wheels immediately behind that, and the rear wheels carry little load. Steering the rear instead of the front makes driving the front wheels much easier, and the vehicle can turn very tightly. For a mower it is nice to have the deck out front, to get to the edge of the lawn without having to accommodate the vehicle's front wheels ahead of it. Rear-steer commercial riding mowers are common.

Rear steering is not good for high-speed stability (which may be why it "seems wrong"), but this isn't a road or high-speed vehicle.

If the mower deck is under the middle of the vehicle, it's easier to control with front steering. In the usual layout of a riding mower (not a lawn tractor) such as the John Deere RX73, the engine weight and driver weight are both mostly on the rear, so there's lots of traction and the lightly-loaded front wheels are easy to steer. Unfortunately, in low-traction conditions you get to turn the steering wheel and watch the front tires skid while the thing drives straight ahead, but that's an inherent feature of steering the lightly loaded tires (whichever end they're on). My front-engine front-steer lawn tractor does this in tight turns on grass.

 

[Electric Land Cruiser]

The plowbot does not have rear steering haha.

It uses differential speed between the drive wheels to steer and the rear wheel is just a caster to support the weight and keep it stable. I.e. the stock mobility chair setup.

 

[brian_]

My buddy build an RC mower/plowbot out of a mobility scooter drivetrain.

The plowbot does not have rear steering haha.

It uses differential speed between the drive wheels to steer and the rear wheel is just a caster to support the weight and keep it stable. I.e. the stock mobility chair setup.

Ah, power chair, not mobility scooter as originally reported; someone not familiar with mobility equipment might not understand the distinction. The drive axle which sameh4 has will be a single motor with differential, so to use the same configuration of vehicle would require the rear wheel to be steered rather than castered.

 

[sameh4]

Ah, power chair, not mobility scooter as originally reported; someone not familiar with mobility equipment might not understand the distinction. The drive axle which sameh4 has will be a single motor with differential, so to use the same configuration of vehicle would require the rear wheel to be steered rather than castered.

Correct, the mobility scooter is a single motor which is why I assumed it was not a diff drive.