Manually shifting CVT

[alexanderfoti]

Hi all

I have a powerbloc 50 I belive, from an Aixam on my bike.

Has anybody had any experiements with forcing a ratio change, by possibly applying pressure to the rear pulley?

When on fast roads, I would like my CVT to shift into top gear at an earlier RPM. I cannot get it to do this with gearing as the pulleys aren't available, and around town its spot it. It would be ideal if I could just nudge a lever and get it to shift into top ratio at say 60 mph. Would be better for fuel economy!

[gilburton]

It's the combination of revs/weight/speed that allows the front pulley to expand against those forces and the spring on the rear pulley.
There is not really such a thing as "top ratio" as the cvt just adjusts to the various conditions.
Manually adjusting cvt pulleys is an old idea and in the days of vintage belt driven bikes such a system was available and I believe some industrial applications still use it.

The CV TEch won't easily convert without a lot of engineering(over to you Tim lol)
Of course you could introduce a 2 speed box in the final drive from something agricultural lol

Apart from changing the rear pulley spring for something slightly heavier (if there is one available) the only thing I can think of is some sort of idler pulley on a pivot under the bottom belt run.
You might then be able to adjust the belt by forcing the pulley open or closed longer??

Does your belt sit flush with the rear pulley edges at rest ??
If not it is worn and will affect your gearing.

[alexanderfoti]

When we are talking about an adjustable idler pushing on the belt, I had in my mind one that pushed inside the sheaves on the secondary pulley, essentially pushing them apart.

I wonder if I could do something with a powerful servo and a nylon pulley or rollerskate wheel.

Depends on how much force it needs, I don't think it would need much if it has to act on the secondary?

[alexanderfoti]

Does your belt sit flush with the rear pulley edges at rest ??
If not it is worn and will affect your gearing.

It did not before, but does now, after replacing the belt.

[coachgeo]

NDSU created a manual shift mechanism for the mini pulling tractor Pg 21 of PDF (pg 16 of the actual document after Title and content pages etc). They used a linear actuator.

https://www.ndsu.edu/fileadmin/aben/Qua ... ractor.pdf

They scraped this concept the next year due to issues not well explained. They scrapped whole CVT and went another direction

https://www.ndsu.edu/fileadmin/aben/Dri ... mplete.pdf Pg 22 /pg 17

[alexanderfoti]

Many thanks. Interesting that they use an actuator on the primary pulleys.

Both links are the same document. Not sure the are meant to be?

[coachgeo]

Both links are the same document. Not sure the are meant to be?

Yeah saw that mistake and fixed it as you were typing

[alexanderfoti]

Having read that, it seems far too complicated for very little gain. Unless a simpler method could be designed to pull the sheaves together (or push the secondaries apart).

I think the latter would be better as the primary in mine is a friction clutch, and the secondary will always be bordering on moving anyway, therefore requiring less force.

[UAofE]

I think a pedal controlled primary could be made using a clutch throwout bearing pushing on rods passing through the outer cover and contacting the sliding cone.
Lighter clutch weights than required for normal operation could be used as a "booster", saving wear on the throwout bearing and fatigue on the operator.

[alexanderfoti]

Having now ridden the new bike combo, I feel like some extra speed could be had by adding heavier weights in the primary and then using an idler pulley against the flat outer portion of the belt.

This idler pulley woukd be mounted on a rod and pivoted at one end. It would be pulled down by a cable, probably on a foot pedal due to the amount of force required.

This would allow best cvt configuration for cruising and mpg but then allow a forced lower ratio for overtaking etc.