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This is an idea that I got from looking at an automatic transmission in my gradfathers shop. There are two sun gears, that create different gear ratios. The planet gears are linked together so that they will spin at the same RPM, but the planetary gearset is both free floating within the entire gearset and can also be locked down (haven't desinged that yet). The sun gears are connected to two different motors; atwood (speed), drill (torque). When you want high speed you fire up the atwood, and it spins the planets, and it spins the ring gear. Same for the drill motor. Your output comes from the ring gear, there will be teeth on both the inside and outside of it. This design needs refinements, and is still being worked on. Problems lie in the fact that one motor must overcome the other; EX: the drill is starting out, it must move the gearset across the atwood, while the atwood is motionless. This issue may cause problems in the electrical system. I would love any suggestions to help me make this design better!
(sorry about the poor resolution)
Ivey
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21-11-2003 16:16
KenWittlief
in an automatic transmission like this in a car, there are clutch mechanisms, called bands, that hold one set of gears still, to get the ratio you want to the output
and dont forget, the torque converter in a car is not only a slipping clutch, it is also a form of hydralic CVT itself (its like a backwards CVT - the motor can vary over a range of rpms while the drive wheels are at a constant speed)
You can get more HP out of an automatic transmission off the line, than you can from a standard one (with a clutch) because the auto can rev up to its optimum RPM
very similar to the problem we face with electic motors - to get the most HP they have to be spinning at the midpoint of their RPM range
25-11-2003 10:25
Mr. Ivey
Yes, I've been thinking about the bands, there are some possibilities of building a one way clutch, and something I'm working on that I call a limited slipping clutch. It works on the idea that the clutch holds the part still until a certain amount of force is applied, then it starts to slip and and all heck breaks loose, not that this clutch will probably be a one time use device. The other big issue I see at this time is the fact that in an automatic transmission there are pneumatic "breaks". They are what hold the gears in the gearset to get the different ratios. I need to find a way to make something like that to make an efficient gearset.
Ivey
22-12-2003 01:55
jburstein
Re: pic: Planetary Gearset
there aren't pneumatics in any slushbox that I'm aware of--it's called a slushbox precisely because it's hydraulic (well ok, so no it isn't... that's because of the aforementioned power-sucking torque converter. Come to think of it, horsepower isn't the only thing it sucks...).
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