Tav + high / low trans concept

[bob58o]

TAV + HIGH / LOW TRANS CONCEPT
Just kinda wanted to throw this out there....

Concept for 2 speed overdrive tranny to be used with Torque Converter. Don't know if I'm on the right track. Pretty sure the numbers are right, just don't know if there are flaws in the concept or design..

Have at it..

I figured the extra jackshaft is needed to keep from having a huge pulley on the axle. The position of axle, Jackshafts, pulleys, and sprockets are altered for simplification...

Low Gear 0.9 x 1.6 x 5 = 7.2
0.9 from TAV
1.6 from 3.6" : 2.25": pulleys and belt
5.0 from 40T : 8T sprockets and chain

High Gear 0.9 x 1.0 x 5 = 4.5
0.9 from TAV
1.0 from 2.25" : 2.25" pulleys and belt
5.0 from 40T : 8T sprockets and chain

Two tensioners (inside the belts), offset from each other, on a single "Forked" Arm will be used to apply tension to either belt. A Lever and pivot to move "Forked" arm, switching tension, and gears.

Low gear 1.6 : 1
High gear 1.0 : 1

This concept behind this Low High Tranny is to gain top end speed, without sacrificing power in the lower MPH range (below 30MPH range)

Low gear 5200 rpm 30MPH
High gear 3200 rpm 30MPH
High gear 5200 rpm 51MPH

I don't know if this design even makes sense.
Tell me why it won't work...
Tell me an easier way..

 

[mindymogul]

Was that made with MS Visio or MS Paint?

 

[itsid]

Well I can't say it won't work..

All I can say is: I doubt it'd work;

and here's why:

first the Tav alone has a powerloss of ~20% if it's in perfect condition.
that's by design (the belt and smooth sheaves mainly)

So adding more pulleys will just increase the losses... further, maybe enough to render the setup completely useless.

So first thing (before even moving past the jackshaft) is a design change (swap pulleys with chains.. still a powerloss but far less!)

Anyways it gets worse further down the powertrain...
The forces in the opposite direction (needed for the Tav to actually shift into high gear)
may not transform ..
I'm too lazy to calculate the exact JS rpms and forces needed to shift, so forgive me not providing the math here.

But I said I only DOUBT it'd work right

I'd say in "low gear" the TC snaps into highest ratio in an instant not providing much additional torque,
and in high gear it'll snap back to 2.6:1 since it will not have the necessary power to speed up the kart accordingly.

I don't know, I haven't tested such idea, nor have I seen a setup like that in action..
but without doing any math.. I have a bad feeling about it.

'sid

 

[Toycrusher]

Theory is decent but I don't think belt friction systems could handle this level of power. And you could have the torque converter issues already discussed

 

[bob58o]

Was that made with MS Visio or MS Paint?

paint!

 

[Poboy kartman]

Hmmmmm....mustery geering..i lick!!!

 

[landuse]

Hmmmmm....mustery geering..i lick!!!

Yes....yes you do....

 

[Jrgunn5150]

I've seen Toque Converter's adapted to 4 wheeler H/L/N/R transmissions, so I really so no reason it wouldn't work.

 

[KartFab]

Not to rain on parade, but it would be hard to REV/MPH match and shift at the right spot without jacking some belts up, but it would work in theory, not sure about in real life.

Calculating when to shift theoretically, then rev match, and MPH match would need a phone/GPS mph app and a tachometer for that.

Might want to investigate a centifugal clutch with pulley if you want to take stress off of the belt, but then where to put it and will it engage at the correct RPM of the given shaft?

Looking at my tiller, the pulley works in the same way, but with no clutch, like just literally throw it in gear, and then pull the lever to engage the belt at 3600 RPM..... seems like a very small pulley at the high rotation rate would work with a large pulley to minimize slip before engagement would be ideal, but engagement MPH goes from 0 to like 1 mph so no huge speed change.

 

[Denny]

No need to worry about rev matching, that would happen automatically when the belts were engaged. The biggest hurdles I see are belt strength, slippage and the shift linkage. The shift linkage alone would be a nightmare!

Denny

 

[Jrgunn5150]

I saw this on another site, the guy had it working, basically the same as an older fourwheeler.

 

[bob58o]

So first thing (before even moving past the jackshaft) is a design change (swap pulleys with chains.. still a powerloss but far less!)

Considered this, but as I could barely turn a wrench 6 weeks ago.... I figured simplest first. I Still don't know how gear selector works inside transmission.

Im already drowning in the shallow end, and I haven't yet googled "Floatation Device!"

Considering the TC / Engine Side

I'd say in "low gear" the TC snaps into highest ratio in an instant not providing much additional torque,

Just to make sure I'm pickin UP what you are laying Down...

Would getting a stiffer TC driven Spring (ie. Yellow vs Green) and adjusting which hole its preloaded in help stay in low gear longer???
(am I at least turning the dial in the right direction??)

and in high gear it'll snap back to 2.6:1 since it will not have the necessary power to speed up the kart accordingly.

So engine size / gearing will have to provide sufficient Torque to the wheels to continue to accelerate vehicle even in highest gear with lowest ratio.

I would have to make sure the engine was large enough???
Would a larger engine allow the use of a TC with smaller axle sprocket directly?
It seems, that even with a bigger engine and smaller axle sprocket, a L/H trans would be beneficial.

'sid

Feel free to ignore any questions I ask. I Know I ask a lot.
Thanks again.

 

[bob58o]

5 speed Lifan 200cc

stumbled across this today>>>>
http://www.ebay.com/bhp/200cc-engine

is this essentially just a $100 Predator with a $1300 5 speed transmission??

 

[NewbCarter]

stumbled across this today>>>>
http://www.ebay.com/bhp/200cc-engine

is this essentially just a $100 Predator with a $1300 5 speed transmission??

As far as i know thats a motorbike engine ... the gearbox is built into it ..

And you can see by the HP / Torque figures its much more powerful than a Predator.

 

[rushking19]

That's over priced for a lifan 200cc 5 speed

 

[B.M.800]

There is a member here that was working on a multi speed belt rig. I dont remember if it was completed.

Another member built a 2 speed gearbox with chains and sprockets. This did work, the shifting was a bit rough though.

 

[rushking19]

There is a member here that was working on a multi speed belt rig. I dont remember if it was completed.

Another member built a 2 speed gearbox with chains and sprockets. This did work, the shifting was a bit rough though.

Can you link the threads I have to see this

 

[B.M.800]

Here, is the 2 speed gearbox. I dont know who the poster of the belt rig was.

 

[bob58o]

That's over priced for a lifan 200cc 5 speed

I've seen some Honda 1300 engines for fairly cheap. I think these have transmissions included. Don't know much about bike engines or transmissions but seems like that might be the simplest way to go about it instead of trying to redesign the wheel or add an expensive transmission to an underpowered engine

 

[itsid]

Feel free to ignore any questions I ask. I Know I ask a lot.
Thanks again.

getting a different driven spring will help.. but only for ONE occasion,
for the low gear setting you'd want the stiffest spring, and for high gear the weakest..
so there's that I'm afraid.

As other pointed out, in the end of all the fabbing of parts it'd be much cheaper to buy a different engine (seeing the smaller 'as powerfull' gy6-es out there come with enough gears to select in a much smaller package for about the same price as a slightly bigger predator...)

I'm not sure, a "gearbox" for an industrial engine is still considered the holy grail...

Chain selector...
I'd forget about a "proper" shifting mechanism and turn towards a springloaded one way clutch like in the minibike two speed transmissions;
that way both chains are engaged at all times (no idler / tensioners needed)
but you can decide which one is free wheeling basically.
Those clutches are not too easy to find, and not cheap either I'm afraid...
still it'd be your best bet if you ask me.

'sid