so the belt moves up and down? wouldnt that require the belt to be stretchy? im not sure where you would find one that would stretch enough. and the springs would have to be very soft to get them to move from the spinning force. I think that since the springs would have to be so soft that it wouldnt do anything because the belt wouldnt stretch easier than the spring.

ok viperdout, i see what you mean, but i dont think you are saying it correctly. Are you sure it's centifugal force that moves the pully? centifugal force moves rotating objects away from the axis of rotation, you need something to move objects along the axis. see what i mean? maybe i just don't follow your explaination, but it seems you got your physic mixed up a bit...
good idea tho.

That's what I said. The pinion on the motor moves away from the motor, increasing the ratio. The belt would have to be stretchy, and the springs would be soft, but strong enough to pul it back. You'd be surprised how much force a pinion can build up. The idea of the cone forces the belt to stretch. a very wide rubber band could be used as the belt.

were you replying to me or sawhit? yes i know how that part works, ive seen it done, but it isnt cetrifugal force that moves the pully in. im not exacly sure how they did it, tho...
btw, a soft o-ring would work really well for your belt. the corners on a rubber band would mess up the movement of your pully.
ill have to think on this some more.

I find that it moves outwards. On my brushless xmod, when you put soft slicks on it, and point the wheel up, the tire flies of the top instead of just getting stuck at the bottom.

What viperdout is thinking of is about half of what is needed.

Viperdout you almost have the same variable clutch system that is and has been used in snowmobiles for years and it will work very well.(some atv's use the same system now also)


look at pages 31 & 33 to see how it works
drive clutch and driven clutch

Sluggbugg, your title is holding true. It does not engage another gear, it raises the belt up, making the gear ratio closer to 1:1, and is completely variable.

http://home.earthlink.net/~graham1/M...ansmission.htm

educate me wise one.please

this site explains centripetal motion. I believe we all should have been saying centripetal all along. not centifugal.

http://www.glenbrook.k12.il.us/gbssc...rcmot/ucm.html

the reason your tire flies off the wheel is because centripetal force loosens the tire's grip on the wheel, thus making it free to move. some other force (ie friction, slight angle, air, imperfections in the surface of the tire) actually makes the tire leave the rim.

I just learned something. Slugg, think about it this way; As that cone moves more inward, the belt will move higher up, because it'll be squeezed up. This will mean more of the belt will touch the pinion at the same RPM. As it slows down, the belt goes back down.

cvt sites

variable clutch system

Okay since i cannot disuade you guys i might as well give you some ideas as reference.

Do you know how a clutch system in a 1/10 GP work? you could extend the the rod on the output shaft of the motor and install a clutch with gear on it. so when the desired rpm is reached the clutch engages and kicks up a second set of gear ratio.

Then again i don't know what tools machinery is required.

Well the CVT's show some promise and using two gearsets to change speed will require one gearset to disengage before the second gearset engages to stop the gears from locking up so a simple clutch system is needed.

I think it can be done and I know there are machines out there capable of making the parts because I made these tiny parts on mine.
http://users.ameritech.net/mlcollins/mmt8s.JPG

Wow, I'm impressed. But i can say for sure if it would work out as expected.

nice, slugbugg. what are those parts? im looking forward to what you are doing. i've run out of ideas for my project, the pinions won't mesh well. ill think on it, but i doubt this one'll work.
good luck to yall with the other designs.

what he's workin on seems like the front axle out of a ttt. what machine did you use to make it?

Those parts are what I was working just before the Xmods were released.
It is an axle for a 1/64 scale 4wd/4ws truck that I may start back to work on now since I really have no interest in the Xmods at this time.
I thought I'd let you guy see just how fine some of these machines can cut.I have other pictures but the one with the dime was the best scale reference I have.

The machine is a taig with a maxnc 10cl controller.(nothing special)

can you give us a link to your machine? and how much did you pay for it?

I can make this work if anyone can get me info on where i can one part:

a one way bearing the size of a xmod bearing upgrade

someone get me onfo on where i can get one of these i and will guarnatee you a workable 2 speed tranny for the xmod.

hey, i dunno if this is what you need but
http://www.zxz-bearings.com/onewaybrg.htm
has some small one way transmission bearings.

lookin foreward to seeing this tranny!

EDIT: sorry those bearings are probly too big. ill look more.they say on their homepage that they will make special bearings to your drawings if you give them designs.

CVT IS simple to do
 

A CVT is very simple, very cheap, and will work and you can get 1:1 ratio on speed. And whoever says a tranny wont make a difference because an electric motor makes max torque at 0 rpms...hahaha that is so funny. Waste of a brain really. When you change from the white gear and swap in the blue gear you are getting top speed in turn for torque( Let me add from an electric motor) therefore you are getting different speeds. The tranny makes the best of both worlds and will work.

All you need is:
-a small cone (can be wood ie. from a craft store) that will go on the motore shaft

-a wood cylinder the same diameter as the largest circumference of the cone (to get 1:1) take this wooden cylinder and attack it to the a bevel gear without the round gear attached (dremel it off)


-and a small sturdy rubber band to connect the two together

very simple and affordable.

I will post a pic of the parts and them together to give everyone a nice view.

I love how you criticize our knowledge when you obviously dont have basic sentence comprehension ability. All those who have said that an electric motor produces max torque at zero rpm, mean that an electric motor produces all the torque it will produce on its on at zero rpm.

actually sawhit is right, the motor will never get more torque than it has at 0 rpm. a gas engine has a power curve with a certain range in which it has max torque.
on the other hand, i still belive that a tranny will make a big difference. bleek, i hope you can get that to work, but i think that the rubber band will just sit on the small end of the cone unless there is a mechanism to move either it or the cone. if you can get that to work, more power to ya. put up a pic.

Here is a idea for a tranny using yo-yo clutches. A 12 year old came up with this... pretty ingenious

2 Speed Tranny

the link doesnt work :( im not redistered threre.

He didn't actually build the tranny...just used the Yomega-style yo-yo as an example of a mechanism. The problem with using that is gonna be one of balance vs. weight. You'd need at least 3 arms to keep the load on axle reasonably balanced, but those arms add weight at a very hi-speed portion of the drive train, where that kind of weight makes a difference. Plus, I had an idea of an expandable collar, but before I even thought about figuring out what it would be made of, I just looked in there and could not find the space. I think given the space and weight requirements, the ideal tranny would have to be electronic so that anything outside basic actuators could be offloaded to another portion of the chassis; with a mechanical transmission, you have to do it with more physical parts (weight) *at* the point of gears meshing.
The biggest step then would simply be any kind of gear-switching mechanism. I'm thinking a raised motor whose polarity has been reversed (either at the motor or at the ESC or, if you connect via Dean's, a polarity-reversing adapter) In that space you've created, two tiny gears of differing ratios (maybe if you're lucky, the stock RS motor pinions will work, and just cut them in half to shorten them) gears connect the motor to the pinion; the gears themselves are connected to each other on a rocker switch. The rocker needs to be electronically flippable so that at any given time, one of those two gears are between motor and plastic pinion (maybe have electro magnets behind each so that turning on one pulls a gear away and pushes the other into the system). Need to shift can be determined any # of ways, but since we're electronic and using Dean's connectors (I'm not trying to shill them, but they're relatively universal), we can add an amperage (load) detector between the motor and ESC such that when load is high, we can upshift; if load is low, we can downshift. Looking in my chassis, there does seem to be room for this, so the big issues would be getting gears of adequate ratio and then...GEAR SYNCHRONIZATION! Maybe if you could electronically lift the motor a hair during shifting, it wouldn't be a problem, but outside that, I really can't think of a good way to get a shift to occur without tearing up the gears.

that's a little like what i had imagined originally. i had wanted to stay away from an electric actuator, cuz that would require more wiring and is a huge hassle. but i guess that is probably the most weight/space efficient and simplest design.

as for the gear, i put up a picture earlier of a gear that had teeth that tapered out, so one end had 2x the teeth of the other end. something like that would provide the more "seamless" or smoothe gear shift that you would want.

to keep the tension on the system, or get you extra hair of lifting for the motor, put the motor on a mount with a hinge on one side and a tension spring on the other. when the larger gear engages, the motor is allowed to move up, but the spring keeps it in contact by pulling it back down. this would also let you shift back down.

hope it helps.

PS: i have a friend that has a small mill, i will show him our ideas and see if he can make a prototype.