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Infinitely Variable Transmission? Answered

Ok, so I have been looking at this thing called the D-drive and it inspired me to come up with my own IVT design which was solid gears for max torque handling and still could change speed and direction easily and smoothly.

This is what I came up with and I would like to hear your opinions on it.  It starts with input to a differential, one side of which is inverted and the other isn't before returning to a second reverse powered differential.  The two sides are slowed using a fluid braking system which has a rotor powered by the side's drive-line, and a flow limiting valve to apply resistance.  As one side slows the other accelerates.  When there is no brake power on either side you have reached a powered neutral, and when the second side is braked the direction changes and accelerates.

So, will it work? How practical is it? Are you going to say it sucks, then steal my idea?


Will it work? Yes.

Is it efficient? Depends on what you're comparing it to.

I will say this: It's good enough for no less than FOUR (4) world-leading agricultural equipment manufacturers to utilize in their most expensive, and most efficient units in the industry.

The only major issue you will have is capacity. If you engage a transmission of this type from "powered stop" into driven output ratios, a lot can happen. Torque output increases with input ratio. Thus, if one fails to decrease that ratio to within torque tolerance of the transmission BEFORE the lash is taken up, a positive lock on the output shaft could allow even a 2hp input to amplify its torque to such degree that it would cause mechanical failure (of the transmission).

So long as you can limit/control input and maximum torque throughput, it works great... just don't warranty anything that you don't proof the controls.

Take a look at Australian Innovation Patent No. 2012100212 – This Patent is available to anyone who wants to use it. The problem with CVT’s such as yours is they are direct drive transmissions, in-other-words, they need a clutch or a torque converter to disconnect the power of the motor/engine from the wheels. Or, if using an electric motor, it must start from zero RPM which has limited torque at
take-off. My system overcomes these problems by allowing the engine/motor to
start turning BEFORE the vehicle starts moving. Also, I have plans to drive a single shaft at THREE different ratios:- (1) an extremely LOW ratio, (2) approximately 1:1 and (3) and extremely HIGH ratio. I think you will like my design: (1) Because it is constant Mesh and (2) Because it converts rotary motion of the Carrier shafts to linear motion of the chains inside the Carrier and then back to rotary motion of the Carrier shafts again. I believe it is the simplest way of achieving Infinitely Variable Transmission. For further details; look up Patent or contact: Graeme John Eddington in Perth Western Australia. Email: Smart-S-trans on smart-s-trans@hotmail.com or s-trans2010@hotmail.com

My version does not require a clutch and can vary 1:1 all the way to -1:1 (reverse) and has an infinite number of ratios in between including 1:0. I would like to see a diagram or model of your idea though as I am not quite grasping what it is from the words in the patent.

Oh boy! I wrote a general response to a number of websites so some of the things I said may not apply to your particular transmission. I understand that it can go all the way from reverse to forward and has a 'gear neutral' position. I was referring to CVT's which cannot reach a 'zero' output unless the input is also 'zero'. What I have a problem with, though, is: at any given ratio it is a 'direct-drive' transmission and therefore controlling the speed of the vehicle becomes a function of controlling the ratio of the transmission. My system overcomes this by being able to spin at any ratio dependent on the torque of the input and the load on the output - it has NO controls or sensors for it to work. I have a photo of my first prototype on one of my three Facebook pages - just type in 'Graeme Eddington' on Facebook: (1) a photo of 'Graeme Eddington' (2) a photo of a Polar Bear and (3) a photo of my machine which I have called: 's-trans'. 'S' being short for sprockets and 'trans' being short for transmission - I think it makes sense. For my Business name, I simply put 'Smart' in front of it - ie. Smart-S-trans which is almost a palindrome and almost says, 'Smartest Trans' when you say it quickly.

I remember reading an article in Popular Science a long time ago about a geared Infinitely Variable Transmission invented by Paul Pires. There are no hydraulics needed, all solid using planetary gears and cams. I've been waiting to see it come out in vehicles, but it hasn't. I googled it, and it's still there. Nice piece, heh?


Two splined cones will do what you want in a very compact space - DAF's CV gear box was very successful. Some cunning engineering required though.

The purpose of this IVT is that it has no friction components (belts and pulleys, or two cones rubbing on each other) This allows for massive amounts of torque flow without slipping. The DAF's CV gear box is constantly not infinitely variable. This design requires no throttle increase to accelerate, and doesn't jerk in via clutch. It smoothly can operate at 0 movement to 100% capacity without any problems, then it can transition to reverse without the need for any gear change.

On a dynamometer OK but high speed and low revs means low torque.

If you loaded the system I bet the speed would fall way back to provide torque for the drive assuming the low revs stay the same.

Assuming this is a break through I will ask the obvious question - Why isn't it in common use?

Well their version is different, and is a low torque over-complicated design. At high speed it would have to rev the engine, this displays how the transmission works though.

I don't doubt it can be done only that a) we don't see it in common use so there are some problems somewhere b) low revs in a petrol engine means low torque - that's why we have the gear box in the first place.

At the other end of the scale build a prototype and show some test results so we can better assess how effective the idea is - Sometimes that's the only way to go!

K, I am working on building one with RC car parts. My main goal is a high torque handling transmission that can engage from 0 smoothly without a friction clutch. My families car runs just above the "green zone" when on an interstate going 75 with this transmission it would be able to reduce the RPMs to the green zone.

My main goal here is for this to be used in farm equipment. The existing CVTs and IVT in farm vehicles are friction based, where out, and can't handle the torque as well.

Your fluid-brakes will get hot, it's a form of friction. But fluid is easy to change.
Have a look at Voith couplings if you're interested.


Why don't you like my brakes so much? You can cool them with a radiator just like tractors have for their hydraulic fluid. Why and how would I use this voith thing, its a fancy torque converter, and all it does is allow for slightly smoother starting and coming to full stops with things like automatics.

I don't object to anything you propose, I see the similarities with other systems from first principles. I'm only pointing to developed functional systems for general interest. I've thought of things like this, but you/I eventually realise that other people have too, and there are good systems in use already.


Ok, how exactly do I make a brake like this though with the information you have provided? I have looked all over and really can't seem to find anything.

Tractor hydraulic drives are notoriously inefficient.

That doesn't really matter, they are used to slow one side down as brakes, I am trying to figure out another way of making a smooth brake that doesn't have friction components to where down.

My dad had a DAF, there were a pair of drive-belts.


Correct this avoids the need to change the drive shaft distance. They also did a lorry version with a steel belt made up of small wedges on a steel band.

And if you're using hydraulic fluid for smooth-transmission, you should look at torque-converters / fluid-couplings.


Thanks, although completely stopping one side with this wouldn't work would it?

Look at epicyclic / planetary gears. The brake-shift method of operation is essentially the same.


I have looked well into planetary gears and I am done with that. The D-Drive which I originally described used them, but it took three equivalent drives to output the power of one.

Forgot the drawing sorry

Its going to be very lossy.