would this transmission design work

[Bobby]

yea it is i need 5 belts, 16 pulleys, 2 sprockets, and a chain

 

[Doc Sprocket]

It's nice to see concepts scribbled out on paper, old school. I thought I was the only one that still did that! However- to play devil's advocate, as I do- wouldn't it be cheaper to buy a CVT, looking at your parts list?

 

[Bobby]

it would toystory but with this set up i can chose my own gear ratio and all the cvt ive had i always had a problem with them

 

[ArachnidBrosMN]

Check this out: I have used this idea before on a kart years ago. Here is a F-R belt driven "transmission"

... looks like they are driving off the back side of a belt though... not sure... can't tell.

A great idea though!!!: your own transmission... would you have 3 seperate levers, one for each speed then????

Edit: I guess this is a F-N-R "transmission"

http://www.youtube.com/watch?v=_-1W7rLaNS0

 

[Bobby]

yes i would, actually 4 levers 3 speed and reverse

 

[Doc Sprocket]

it would toystory but with this set up i can chose my own gear ratio and all the cvt ive had i always had a problem with them

Whatever works for you- but I had to make the point. And maybe you've had bad luck or something, but a Comet 40 will outlive you.

 

[Bobby]

but they're alot more expensive too

 

[r97]

As I understand it you are twisting a v-belt to gain reverse, right? If so I would look into running off the back side of a v-belt, chain, round belt, or flat belt. Just like the video ArachnidBrosMN posted. To me at least, it seams as though twisting a v-belt would cause it to rub against itself a lot, and have a tendency to jump out of the pulley. If you really want to stick with the twisted belt idea I would advice you to get a long-ish belt rather than a short one. Doing that would minimize the issues I mentioned above.

I also agree that a CVT would be a much simpler, reliable, and lower costing system, but if you want to put in the effort to make this setup work I would encourage you to do so. You should also setup the system so you only have one, or two levers to operate instead of four.

 

[Bobby]

1. i figured out a way to keep the belt from rubbing against itself
2. if i work out all the bugs in this system it would be just as reliable as a cvt and still less expensive
3. 4 levers make the design simpler instead of designing 1 lever to switch between 4 gear(3 including reverse)

 

[r97]

I can't be 100% sure but you might still run into problems with the belt trying to jump off the pulley, only testing will tell for sure. Have you calculated the price yet? All those belts, bearings, jack shafts, pulleys, and idler pulleys would start to add up, maybe not $400 but still a good chunk of cash. The 4 levers are certainly simpler to build, but I personally would find one or two levers much simpler to operate and less cluttered looking.

Also, just in case I'm coming off the wrong way, I'm NOT trying to discourage you from building this, but rather I'm trying to point out any potential problems so you can sort them out now when you still haven't spent any money.

 

[Bobby]

the price for everything (i think) is about $300 give or take $50

 

[Doc Sprocket]

the price for everything (i think) is about $300 give or take $50

Given that, and a copious amount of R&D, tinkering, tweaking, troubleshooting, etc- the cost of the CVT makes it a more practical solution. However- not everything we do is entirely practical, and we have our reasons for these decisions. So-

Good luck, and build on!

 

[Bobby]

toystory i have this "gift" where mostly anything i build usually works 1st or 2nd time so the belt drive is still cheaper because all the parts would cost a max of $300 (its more like $200-$250)

 

[ArachnidBrosMN]

Hey, not to be "that one guy" that suggests something totally random, but I've seen (on older "Bobcat" loaders) manually-operated CVTs that are built using a regular wide-belt, but two pulley-plates that slide on a greased shaft, operated by ONE lever that the rider moves. This setup is also found on some old John Deere tractors, where "the farther you push the lever... the faster you go" meaning: the hand-clutch not only puts the vehicle in gear, but it spreads the spring-loaded pulley apart according to the operators wants.

I know it sounds far-fetched, but if you could invent a way to do it... you would be worshiped.... "a cvt that you can control"

Edit: When the operator of the vehicle pushes a lever... it pushes the driver-pulley contact-face closer to the belt and engages... and the driven-pulley acts (spreads) normally, responding to belt tightness.

 

[mckutzy]

I think this will take up a fare amount of space but the buggy will have a bit more room than a gokart for the linkage to the trans idlers(connecting rods or cables). A transmission that comes to mind, having multiple gear levers is LENCO ST1200, (yes this is a racing transmission)

Now I know this is directly connected to gearing system, but I think something like this could be done.

I think the biggest problem will be keeping each belt engaged(under tension) without it inadvertently disengaging from a bump or the like, and equally speaking, disengaging when the previous or consecutive lever is pulled, so as to not have multiple levers with multiple locking devices to manipulate all at once with one hand.
(an example from a switching station for an old train yard)
http://zippy.cso.uiuc.edu/~roma/signal/75thStreet.html

I could see that looking a bit like a forklift except front steer and having no forks, but overall I do like the idea of this if you can pull it off.

 

[Bobby]

my transmission is in the back of the cart with the engine. i have a "shifter box" on the floor of the cart to change my gears with. they're levers to engage/disengage each gear

 

[ArachnidBrosMN]

Sweet... I can't wait to see it all come to life... don't give up.

 

[Bobby]

you could see it come together faster if you donated some money to me for it lol

 

[r97]

Hey, not to be "that one guy" that suggests something totally random, but I've seen (on older "Bobcat" loaders) manually-operated CVTs that are built using a regular wide-belt, but two pulley-plates that slide on a greased shaft, operated by ONE lever that the rider moves. This setup is also found on some old John Deere tractors, where "the farther you push the lever... the faster you go" meaning: the hand-clutch not only puts the vehicle in gear, but it spreads the spring-loaded pulley apart according to the operators wants.

I know it sounds far-fetched, but if you could invent a way to do it... you would be worshiped.... "a cvt that you can control"

Edit: When the operator of the vehicle pushes a lever... it pushes the driver-pulley contact-face closer to the belt and engages... and the driven-pulley acts (spreads) normally, responding to belt tightness.

My neighbors craftsman lawn tractor and my drill press use the same system. I have always thought it would be a nifty thing to have. It would be very simple compared to a transmission with set ratios, would operate smoothly, and it would have a built in clutch. I would really enjoy being able to keep the engine just above idle and cruise around at 15mph.

 

[Bobby]

once the cart starts moving i could do that in 1st gear