JIM5.0

I agree too here. The belt is the weak link. Norm is right, in order for CVT to be able to take the massive amounts of torque from our V8s, especially modded ones or big blocks, the belt must be reinforced.

As a child, the concept that I actually envisioned was two cones directly interfacing each other. The cones had teeth cut into them and to vary gear ratio, you move one cone in and out accordingly but keep the cones in contact to each other and the teeth meshed.

My vision was like the Evans friction cone design:
http://en.wikipedia.org/wiki/File:Ev...neHagley01.jpg
But to eliminate the possibility of slip from massive torque, teeth would be cut into the cones.

The problem I see here with my teeth idea is as the cones slide in and out, it is impossible to reduce teeth number and yet get infinitely variable gear ratios. The gear ratios would be stepped and you have to have a "clutch" mechanism to allow the cones to temporarily separate to jump down to a lower tooth count part of the cone. Thus the problem of gear shift jerk again and more moving parts.

Also, assuming you can keep the toothed cones together without ever separating the ones physically, the next obstacle would be maintaining gear mesh because the cones move in two axes (plural of axis) because a cone or both cones will have to move in and out, and also left and right to remain in contact with each other.
There will need to be very good precision in maintaining proper gear mesh of the teeth for all possible positions of the cones throughout all the gear ratios.

Norm Peterson

Back when the only cars that I had access to were automatics, I actually spent some time sketching up a shifter mechanism that would have more closely mimicked the H-pattern of a manual. That was probably 30 years before I'd learned the little throttle kick trick, and it certainly wouldn't meet any current interlock requirements.

Somebody who knows how to hack the PCM could probably build in the throttle kick capability electronically, but I think that would actually detract from the driving experience of getting it right on your own.


Norm

Norm Peterson

You'll also have to accept greater losses to the increased hydraulic requirements, as that's where the ability to transmit greater torque when the drive side pulley is in its smaller diameters is going to come from.

I wonder how the current fans of conventional automatic transmissions will look at the CVT . . .


Norm

daredevil95

I never drove a car with a CVT tranny....that would be my 1st step.

Back when the only cars that I had access to were automatics, I actually spent some time sketching up a shifter mechanism that would have more closely mimicked the H-pattern of a manual. That was probably 30 years before I'd learned the little throttle kick trick, and it certainly wouldn't meet any current interlock requirements.

The H pattern would only change the shifting dynamic as far as appearance is concerned. A good example would be an Oldsmobile Hurst/442, these car types played around with shift patterns including the "His and Hers" and "Lighting Rod Shifters"....looks cool but, no real advantage other than styling/cool factor. An automatic will only shift as good as it's internals are designed. The shifter is a devise to operate the transmission's internals. I usually laugh when I see paddle/button shifters on cars like the Camaro SS or C6.....the only advantage to those shifters is keeping both hands on the steering wheel.....maybe that's the goal? It's not worth the extra cost. A lot of people relate this type of paddle shift to "Ferrari transmission"....NOT EVEN CLOSE!!! The real technological break through in the automatic transmissions are with the Direct Shift Gearbox. This is an incredible transmission that could be driven in either automatic or manual transmission applications. We usually find these transmissions in high end cars like the Ferrari's and Porsche's. The magic of the Direct Shift Gearbox is the dual clutch systems which translates into one transmission with 2 internal transmissions. As an example while in 1st gear the other shaft is already in 2nd gear waiting for engagement which makes up-shifting Lighting Quick....awesome technology! This transmission could be driven in either full automatic or full clutch mode, we have the best of both worlds. This technology trickled down from F1 Racing and has been finding it's way into road cars.

As nice as Direct shift is....I would still choose the old fashion manual gearbox. This technology keeps it simple....Shifter/clutch/transmission. There are no electronics and for me a better driving experience!

I would like to see Ford to start refining the Direct Shift Gearbox for the Mustang. They could make it affordable for us Mustang owners!! I'll pass on the CVT transmission in my Mustang....put it in a Focus!!

http://en.wikipedia.org/wiki/Direct-Shift_Gearbox

Norm Peterson

Further outside the box than appearance or either of those examples, because I was looking at cars from a road-race perspective rather than as a drag racer even then. With the exception of Chrysler's pushbutton Powerflite and Torqueflite transmisssion controllers (and a few similar devices used occasionally by others), all of the AT shifters I've ever seen favor manual upshifts over manual downshifts. I was mainly after full manual upshift AND downshift capability, between any of the forward gears, with the retention of closer to MT "character" as a secondary goal.

It was intended to give positive gear selection positions without the notchiness of the basically inline conventional pattern or a ratchet that really only works one way at a time until you do something to reverse its action. The possibility of overshifting through "D" into "N" was to be eliminated completely via the use of a reverse pattern valve body and I think the 1-N "gate" was to be spring loaded. I don't remember much more.


Norm

JIM5.0

Do you mean the hydraulic pressures needed to keep the cones in position? If the positioning of the cones is done hydraulically and held in place hydraulically, then absolutely, the necessity of having much higher hydraulic loads to maintain the cone positions are a must.

But in current CVTs, are the cones moved by rigid machined parts that move and hold the cones in place? And the hydraulics are there only to actuate the mechanism that moves the cone positioning parts?
I do not know this part about CVTs as they are employed today.