I have a son that has muscular problems. He has friends that have go karts and wants one. First I will say pushing a throttle and break is hard for him. The break is to hard and the throttle tires him out. I was thinking about electric motors controlling the break and gas. But wouldn't mind going all electric. I'm stumped on how to do it. My biggest problem is my budget. Any ideas.

 

Electric would be the way to go, but expensive. The whole thing could be controlled with hand throttles.

 

Can we assume he has full control with is hands? Anything less than 100% would start to raise safety questions. Better disappointed than injured.

Motorcycles have mechanical control purely from the hands, so it's doable with existing and off-the-shelf technology. Just gotta do it safely.

Just google "hand control go kart" and you'll see how the commercial products do it.

 

Yes I have thought about the hand control but the breaking would be my only concern. My son has full use of his whole body just not much strength. Safety is my #1 priority that’s why I went with a go kart. They have full roll cages and I could put a 5 point harness in it. I am thinking of using a 90 degree gear motor and a rheostat for break control. Thanks for the help so far.

 

Motorcycle hydraulic disc brakes are quite powerful and require only a small hand force to stop even a large motorcycle. You could likely use disc brakes with a motorcycle master cylinder to get good stopping power even with a moderate foot force. The length of the lever arm used to press the master cylinder piston will determine the actual force required.

Will all four wheels have brakes? What would be the wheel diameter?

 

I'm not too experienced in this area, but my 2 cents are to use a failsafe brake rather than standard, something where the resting position is braking rather than coasting

For steering, an option is using feet to steer, amd then hands for throttle/break
In high school me ang a couple other guys built an all electric vehicle with those controls, I believe it was called a steering square or steering box

Once you get used to it it's much easier to drive than cranking a wheel all the time, with much less exertion

I'll see if I can find spme pictures to upload tomorrow

do you already have a gokart you're working with?

 

Yes I have thought about the hand control but the breaking would be my only concern. My son has full use of his whole body just not much strength. Safety is my #1 priority that’s why I went with a go kart. They have full roll cages and I could put a 5 point harness in it. I am thinking of using a 90 degree gear motor and a rheostat (probably not needed unless motor is very large)for break control. Thanks for the help so far.

Motor braking is nice, and will be very effective through a 90°gearbox.
However freewheeling is important on most vehicles.

Go with a standard PM motor an belt or chain drive. You can easily get 6/1 or even close to 10/1 reduction.

Use two motors. One on each rear wheel. Or even two on each wheel, as small scooter motors and controllers are small, light, inexpensive and reliable.

Hall effect twist grip, thumb lever, and foot controls are available.
http://tncscooters.com/index.php?route=product/category&path=52_55


I've built a few electric go karts for my kids and grandkids. (small)

The way they play, there was no need for throttle. I used redneck pulse width modulation. Thumb buttons on the steering, controlling automotive solenoids.

They quickly adapted to quick jogs of the button to control speed.
If it's over powered this wouldn't be safe of course.

Don't forget a master control relay from an accessible safety kill switch.

As mine were slow. Under 20mph, and used on level ground. I used dynamic braking, only, from a foot switch.

I also wired my motors thru a series/parallel switch. Offering a slow ride for the pre-schoolers.

Your project may be for much heavier riders wanting more performance, but I thought I'd relate my experience.

 

Your project may be for much heavier riders wanting more performance...

That's an excellent point. It's inevitable that a kid will let his friends try his machine. It's equally inevitable that one of them will push it to its limits of acceleration, turning, and braking. You always have to design for worst case.

 

Here is a motor I've used. Last project used one on each wheel. Powered by 12vdc. Plenty of power for my slow kart even at 1/2V.

Every few years I email the source to see if he still has a supply.
Had more as of: Sent: Sunday, April 24, 2011 8:33 PM

I should've ordered more of them. I only have two left.

 

Thanks for all the useful information INWO. This is exactly what i was looking for. I will start looking into this and try and keep everyone up to date on my progress. Thank you everyone for the help.

 

Here is a "clown" drag car that I made using two of the motors shown.

Still winter here, so it's hidden under my boat.

The container on the front holds a water bottle for balance.

The butterfly steering has to thumb buttons to control wheels individually.

Toggle switches set direction of each. Foot switch for motor braking.

It will jump up on wheely wheel and chirp the tires.
Holding one button, or both with opposing direction, will spin in place on the rear wheels.

Low center of gravity lets it go from top speed to spin in a couple car lengths.

A control switch in the back puts it in toddler mode, with the two motors in series.

#25 chain drive. Smallest sprocket I could source on the motor and largest that would fit on the wheel. I think about 8-1.

Intention was to debug it and go to 24V but never did. Largest rider is about 100lb except when I squeeze my 220 into the childs car seat.