Need advice on motor, battery, controller, for overhead cable car

[ChuckB]

Hi, I'm building an overhead cable car (not sure what to call it) and I need some advice on what motor/controller/battery combination to use. I hope I put this post in the right section.

There will be a wire going through my woods, supported at regular intervals by a bracket attached to the side of trees. There will be a seat to sit on and an electric motor which will be capable of going either forward or reverse.

Here is a video of the early progress I've made:
https://www.youtube.com/watch?v=Er6zJBmLhlc

Basically there will be two caster wheels to hold the weight, and a third wheel in the middle which will be powered. The powered wheel will be pneumatic so that it has better contact with the wire. It will also be on a lever, so I can engage/disengage it from the wire.

My problem is I have no idea what size motor I need. I figure it will weigh about 300-350 lbs including me. I'm guessing I need a 500w 48v motor, but would that be too much power? I don't want to go super fast, I just want it to go maybe 5-10mph with no problem.

Any insight is greatly appreciated, thanks.

Chuck

 

[Skaiwerd]

You’ll probably need some sort of reduction. Most motors spin say 3000 rpm and you need say 300 rpm for an ebike to work properly and not burn out your motor or controller. For your project you may need even more reduction to keep it slow and powerful. Lowering the final rpm increases torque in the same ratio.

 

[ChuckB]

Ok, I was planning on 10:1 reduction, but I'll think about doing more than that.

 

[dustNbone]

You'll want to do the math on your gearing, based on the diameter of the wheel you're driving and the speed of the motor you're dealing with. If the driven wheel is small enough, a small geared hub motor may well put you close to your desired speed.

You might be able to apply some kind of traction surface directly to the outside of the hub, effectively making it a very small wheel.

As the wheel is directly driving on the cable, the calculations for rpm/speed are the same as for a bike.

 

[ChuckB]

Thanks for the replies. I went with this motor, a 500w 48v 6:1 gear reduction motor
https://www.ebay.com/itm/48V-500W-Electric-GoKart-Tricycle-Brushless-Motor-Gear-Reduction-w-Controller/233301591728?hash=item3651dbc6b0%3Ag%3AuVwAAOSw9aJdQUOr&LH_BIN=1

A geared hub motor would be simpler but I'm not sure what I would do if the gearing isn't enough. With the separate motor I can additional gearing if needed.

 

[flat tire]

The size / power of the motor is roughly what it can tolerate for some continuous period, not what it will put out at all times. You can control the output torque / speed through your controller programming (if applicable) and / or using a throttle.

Make sure to get a controller that has reverse. Not all controllers have it.

Think about it, if motors put out their rated power at all times our fast bikes would be totally uncontrollable!

 

[dustNbone]

A geared hub motor would be simpler but I'm not sure what I would do if the gearing isn't enough. With the separate motor I can additional gearing if needed.

That's why I suggested doing the (simple) math before buying things.

 

[amberwolf]

YOu might want to look at http://ebikes.ca/simulator to work out the power needed to do what you want.

It's designed for hubmotors, but you can customize the setup to emulate the kind of stuff you're doing instead, though you'll still need to do the math on the wheel size / gearing to get the RPM of the motor vs the speed of the system worked out.

I strongly recommend reading the entire page there, and playing with different existing systems, to see how it all works together, before working out your system on it, so you get a better idea of what's going on when you change things.

 

[ChuckB]

Hi guys, I finally got the motor and drivetrain working. Here's a video

https://www.youtube.com/watch?v=EBIFFykNipA

It works really well. It took a lot of trial and error. Now I just need to build a box for my laptop and figure out how to control the throttle with an arduino. Also need to add a couple cameras.

 

[flat tire]

Nice design, very clever.