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Video: Is Steve Durnin's D-Drive the holy grail of infinitely variable transmissions?

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May 13, 2010

The D-Drive: it could be a gearbox revolution, if only people could understand the thing!

The D-Drive: it could be a gearbox revolution, if only people could understand the thing!

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Ready for a bit of a mental mechanical challenge? Try your hand at understanding how the D-Drive works. Steve Durnin's ingenious new gearbox design is infinitely variable - that is, with your motor running at a constant speed, the D-Drive transmission can smoothly transition from top gear all the way through neutral and into reverse. It doesn't need a clutch, it doesn't use any friction drive components, and the power is always transmitted through strong, reliable gear teeth. In fact, it's a potential revolution in transmission technology - it could be pretty much the holy grail of gearboxes... if only it wasn't so diabolically hard to explain. We flew to Australia's Gold Coast to take a close look at the D-Drive - and it looks to us like Durnin has pulled a rabbit out of his hat. Check out the video after the jump and see if you can work out if there's a catch.

Geared transmissions - a useful compromise

In basic terms, the idea of a gearbox is to create the ideal level of mechanical advantage between a motor and its output. Motors of all kinds have a speed of maximum efficiency, and a speed of maximum power, and you use a gearbox to decide what engine speed you're running compared to the output speed.

In a car, that means you want a low gear at low speeds or for quick acceleration - because in lower gears, the engine revs harder and produces more power. Cruising on the freeway, you want a high gear that lets you trundle along using the minimum practical engine RPM so you don't waste fuel.

So most gearboxes offer a compromise - manual, semi-auto and auto transmissions offer you a set number of gears you can choose to find one that's close to the ideal ratio for what you're doing. But there's efficiency losses in between gearshifts as you disengage the engine using a clutch - or in the case of an auto, a torque converter. And although some geared transmissions offer lots of gear choices, every set gear ratio is a compromise.

And the clutch itself is a fairly crude device - when you're engaging a clutch, you're basically pushing a set of plates together, some of which are coated in high-friction material, which grab the other plates and force them to spin. This approach is inefficient and prone to slip and wear under large power loads.

Variable transmissions - very good, but not quite

Then there's Continuously Variable Transmissions, or CVTs. The CVT is in theory a much better solution, because it allows a constant range of gear ratios between low and high gears. Scooters use them, as do some cars nowadays - with a CVT, the engine can sit at its most efficient or powerful RPM, while the gear ratio constantly adjusts itself to match wheel speed.

But most CVTs have a limited range of ratios they can work through - so while you can transition all the way from low gear up to high, you can't go all the way down to neutral. So they need to use a friction clutch or torque converter to get them started from a standstill - and what's more, in order to achieve variablilty in the gear ratio, they're almost always built around some sort of friction drive too - like belts pulling on conical rollers, or rollers being mashed against toroid shapes.

All these friction components cause troubles when you start trying to put high power and torque through them - they start to slip and fail, they wear and generally contribute to inefficiencies in the drive train. That's why you tend to go back to gears when you're designing a high-powered machine. Gear teeth are reliable - the bigger the teeth, the more power they can handle.

The D-Drive - infinitely variable, no friction components

If all this gearbox talk seems like a long setup, it's kind of necessary to understand the problem when you're looking at the solution Steve Durnin has come up with.

Because at the heart of it, what Steve has managed to do is create a gearbox that:
  • requires no clutch at all;
  • is infinitely variable - from top gear through neutral and even into reverse; and
  • doesn't use ANY clutches or friction drive components - instead, the power is ALWAYS transmitted from input to output through gear teeth.
The D-Drive's twin spinning shafts determine the final gear ratio.

But how on Earth do you obtain infinite variability using gears? After all, a cog's a cog - it's not like you can make them magically grow and shrink in size.

The answer is that you've got to stop thinking about gear sizes, or cones and belts, or any familiar transmission picture you have in your head, when you're talking about the D-Drive.

Because when you look at it, the only way to tell what sort of ratio it's in at a given moment is to look at the two spinning shafts in the middle of it. If the bottom shaft is still and the top one's turning, you're in top gear. If the top shaft is still and the bottom one's turning, you're in reverse. If the top and bottom shafts are spinning at the same speed but in opposite directions, you're in neutral. And you can speed up or slow down those shafts as much as you like to vary the gear ratio to any point between full speed reverse and full speed forward.

You really have to watch the attached video to start to understand how this gearbox works - but in essence it's built around planetary gear systems at either side, with sun gears, planet gears and revolving ring gears all interacting with one another.

The D-Drive's output planetary gear system.

The energy efficiency equation

In order to control the spinning speeds of the upper and lower shafts, you have to input a certain amount of energy - for instance, to put the D-Drive transmission into neutral, you have to spin the bottom shaft around at a speed that equals the speed of the driven top shaft.

But according to Steve and his engineers' calculations, the energy you put in to do spin that bottom shaft is only a tiny fraction of the energy your main engine is running. All that energy has to do is to spin the planetary gears around one another in such a way as to effect the final ratio.

And you can do that in a number of ways. Steve's current demo prototype uses electric engines both as the input engine and to spin the control shafts as needed.

But, taking the example of using the D-Drive in a car, you could easily use an auxiliary electric motor to control the gear ratios, or a kinetic energy recovery system, or some sort of regenerative braking system. You could even harvest energy directly from the driven shaft and use it to spin the control shaft.

Steve's prototype is only sufficient for demonstration purposes - and you'd have to question how effective a demonstration it is when just about everyone that looks at the thing is left scratching their heads and wondering 'er, so how exactly does that thing work again?'

The D-Drive's input side - a ring gear mounted eccentrically in a large orbital gear.

The next step - building a test rig

Durnin is currently in the process of raising funds to build a test rig - a strong, metallic rendition of the D-Drive with the ability to measure how much energy is going in at the input end, what's coming out at the other end, and how much power is being put into the control shafts - but he and the engineers he's consulted are confident that the D-Drive will be proven to be "an order of magnitude more efficient" than existing gearboxes.

The implications are pretty huge if he's right and the numbers come up looking good; as a geared system, the D-Drive is scalable in the extreme, and could remove the need for friction components or manual gearboxes in everything from cars, motorcycles, trucks, industrial and farm equipment, massive marine applications, wind power generators... basically anything that's got an engine.

Because it's all gears and bearings, reliability should be excellent and servicing or repairing the D-Drive a snap. Because you just need to spin (or lock) those control shafts to come up with your final ratio, you could use anything from a fully computerized smart control system to a manually applied pin through the control shaft to change your gear ratios, making it useful in certain very low-tech situations as well as extremely tunable in an automatic automotive application.

About the inventor

Video: Is Steve Durnin's D-Drive the holy grail of infinitely variable transmissions?

Steve Durnin is a plumbing inspector from Queensland, Australia, who has been tinkering with the D-Drive and several other ideas for more than 20 years. The "D" in D-Drive, incidentally, stands for Durnin.

This is the first invention that Steve has tried to patent and commercialize, so while the D-Drive looks very promising, it's taking him some time to push through the relevant channels. His demonstration prototype and patents were paid for by a small group of private investors, who stand to gain a heck of a lot if the D-Drive cranks out the right numbers on a test dyno and breaks into the market.

We thank Steve for his time and wish him all the best with the D-Drive. It's a diabolically hard invention to understand even when you're looking at the prototype in action - so he's one clever cookie to be able to come up with the concept from scratch, particularly seeing as he claims he had never heard of a planetary gear system before he'd designed one as part of the D-Drive.

Quite an achievement!

Steve can be contacted through his (very embryonic) website.

UPDATE

For an update on the D-Drive and the reaction it has sparked click here.

About the Author
Loz Blain Loz has been one of Gizmag's most versatile contributors since 2007. Joining the team as a motorcycle specialist, he has since covered everything from medical and military technology to aeronautics, music gear and historical artefacts. Since 2010 he's branched out into photography, video and audio production, and he remains the only Gizmag contributor willing to put his name to a sex toy review. A singer by night, he's often on the road with his a cappella band Suade.   All articles by Loz Blain
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58 Comments

Seems like a reincarnation of what the Toyota Prius has been using for years. Only the Prius system looks a lot less complicated and better suited for hybrid vehicles and energy recovery. The Prius system is essentially a planetary gear (or differential) in which both the sun and planetary gear cogs are driven producing the same effect of a CVT, with reverse, without a clutch or friction system to interrupt torque. Check the link for an animation: http://www.wind.sannet.ne.jp/m_matsu/prius/ThsSimu/index_i18n.html

jeffbloggs
13th May, 2010 @ 08:20 pm PDT

This is probably the most important invention I've seen yet on Gizmag. High-impact because it can be employed today. Excellent reporting too guys.

Yes, it does function similarly to the Prius system. However you have to appreciate what a gigantic leap it is for all vehicles, hybrid or not. For aircraft and boats it allows you to get rid of the variable-pitch propeller.

This may also represent a big blow to the Hybrid platform. It allows constant-speed running of the ICE; a primary benefit of hybrids. For ICE cars, it is a godsend that allows you lose not only the gears but the clutch as well. And the weight of hybrid batteries.

This is a really, really big deal.

Todd Dunning
13th May, 2010 @ 10:10 pm PDT

While interesting from a gadget perspective, the invention is likely to be as effective as the proverbial perpetual motion machine. While it does effectively vary the drive speed, it will not effectively transmit torgue efficiently over the range of the input-output shaft relation. The reason being that the input to the control shaft(s) must be sufficient to counter the torgue being applied at the input. One could effectively dispense with the motor used in the demo for the control shaft and place a brake band as used in any conventional automatic transmission. By allowing the brake band to slip the control shaft will be observed to rotate and the output shaft speed reduced in relation to the amount of slip allowed in the control shaft. This becomes wasted energy. The energy derives from the torgue applied to the shaft. The machine effectively then divides the input energy between the output shaft and the control shaft. The machine is interesting to observe operating, but does not present anything new from a mechanical engineering perspective.

NoResponse
13th May, 2010 @ 10:16 pm PDT

Looks like a simple differential mechanism to me. Kind of interesting that the control shaft needs to be driven by a CVT!

Michael G. Belanger
14th May, 2010 @ 05:32 am PDT

No, not the holy grail. Reducing drive output speed with a power take-off shaft (PTO), control shaft or whatever you want to call it is an inefficient waste of torque, regardless of whether you use it to drive a generator to be later reclaimed as in the Prius application. The shimano 27 speed chain drive on my bicycle is more advanced than this, not to mention the Rohloff and Davinci hub gear transmission concepts which are more efficient.

Oh, and to Mr Tod Dunning - no this will not eliminate the need for variable pitch propellers, those are used to maintain RPM due to tip-speed limitations, see 'constant speed propeller'.

This sort of thing would work nicely on a train, but as aforementioned the concept already exists.

PeetEngineer
14th May, 2010 @ 07:14 am PDT

WOW what a concept almost a confusing as the W engine

Facebook User
14th May, 2010 @ 07:38 am PDT

Steve Durnin has come up with something unthought of before and of course there will be detractors all saying blah blah blah ! I watched this demo many times and I'm convinced he has got something that will hit the automotive world in a big way, I watch with interest how this plumbers idea comes to fruition, and thank you Gizmag for yet another well put together piece of reporting

robinyatesuk2003
14th May, 2010 @ 08:18 am PDT

I am from Australia and saw this guy on a TV show we have here called "The New Inventors" (There was a show years ago called "The Inventors"). I could not work out how this things worked either but this guy came across as pretty normal, quite genuine and very excited about what he has done. On that basis, and the fact he made it onto the show, I started getting excited too. Like others here I can see the potential although I will say to Todd Dunning above that this system is not needed for aircraft - they are limited by propeller tip speed so a huge speed range is not the best option. If this thing does go ahead, and we are all using some sort of fossil or renewable carbon fuel in the future, I like the fact that we might be able to design engines for cars etc that are designed to run at one optimum speed (like aircraft engines) with all the efficiency benefits that brings. And a lighter, more efficient gearbox means everything else can be that much lighter and more efficient as well.

We have a long history of not backing our inventors in Australia - it is often US, European or Japanese investors who have the vision and buy the technology. It would be very sad if that happened with this invention - given the potential application in the lives of every single one of us!

Hogey74
14th May, 2010 @ 08:25 am PDT

Noresponse- if there is energy available at the control shaft, why not have a motor generator on it. Generate power in the forward ratios and use it as a motor to make reverse happen.

God job Durnin!

foghorn
14th May, 2010 @ 08:26 am PDT

This transmission is almost identical in operation to a Constant Speed Drive used on aircraft jet engines. They are used so the electrical power stays at a constant 400 hertz while the engine speed changes from idle to max rpm. I thought it was pretty neat idea when I was trained on jet engines back in the 70's and they have been around a lot longer than that. I've always thought it would be interesting to apply the technology to cars but in reverse. Constant speed input (such as a turbine engine running at 100%) to variable speed output (The wheels).

Gary Reed
14th May, 2010 @ 08:29 am PDT

I think it is really quite brilliant. To eliminate the need for a torque converter or clutch is gigantic in its implication. A variable transmission with positive, not friction drive.

Good job!!!

Facebook User
14th May, 2010 @ 08:43 am PDT

Just a variation on an old theme. The problem areas are in what is not addressed, the things we aren't shown, the drives on the back of the prototype. He has electric drive instead of whatever clutches or other things would be needed to give a variable speed, so it's effectively a variable opposition drive where you use the second input to undo the effect of the main drive path.

If you just consider the output gears, when reversing the inner gear needs to be driven with the reversing torque, so it takes the same sort of load as the primary, however it is supposed to just be a control input. Not so. This reminds me of the Wizard of Oz... ignore the fool behind the curtain. In this case, ignore how those two shafts are driven.

It is really just an undeveloped version of the John Deere IVT, the difference is that the John Deere transmission has been hauling plows around in several feet of clay for years. In the IVT a hydraulic motor, powered by a transmission driven pump, provides the variable opposing drive. Other tractor companies have similar industrial grade, tried and tested, variable transmissions. There's nothing new here.



chann94501
14th May, 2010 @ 09:08 am PDT

Ehuff already how do we invest or help, as we want to jump on this INGENIOUS BREAKAWAY! KUDOS TO THIS SPARK OF GENIUS ALIVE AND KICKING IN THE LAND OF DOWNUNDER!

cretus
14th May, 2010 @ 09:26 am PDT

Call me a skeptic, but I don't see the novelty here. It is very much like the torque-sensing constant speed drives used in machinery for years. It is very clever, however.

BTW, it does not negate the need for controllable pitch propellers, which are necessary for different phases of operation (speeds, altitude, thrust needed), and to prevent the blade tips from exceeding the speed of sound.

W7SVJ
14th May, 2010 @ 09:27 am PDT

@jeffbloggs

I agree, I think this is similar to the Hybrid Synergy Drive developed by Toyota which also does not involve any clutch or belts.

http://en.wikipedia.org/wiki/Hybrid_Synergy_Drive

Steve Durnin hasn't come up with anything new and I am sure Toyota has already patented it.

arnuxii
14th May, 2010 @ 10:48 am PDT

Actually, it would have been nice if he'd invented this fifty years ago. We'd have saved lots of oil. But now, the internal combustion engine, the one that needs to be going at a particular RPM in order to be efficient, is on the way out. You don't need constant speed with an electric motor as the primary driver of your vehicle. And electric motors, powered by batteries or fuel cells, are going to be the future of powered personal mobility.

HenryFarkas
14th May, 2010 @ 11:16 am PDT

@Michael G Belanger

Yea. You are right.

A CVT to drive the control shaft. LOL.

He's not removing the CVT from the system merely moving it to a different place in the system. Now I'd be hopeful to see if that has actually made a difference in the system's efficiency when they do do a full prototype.

Karan Checker
14th May, 2010 @ 01:41 pm PDT

Still sceptic about the efficiency considering we pop the clutch in split seconds and generaly stay for a long duration at the rev with maximum torque, some apps will be great though. On safety, if the small control shaft motor ( or other propulsion options) fails we are at full blast directly bolted on the power source!!

Apichat
14th May, 2010 @ 08:30 pm PDT

This system has been patented by Darcy Gabriel Of Prince Gorge BC Canada in mid 90s. I have seen it work using a 50 HP Gasoline Engine

waltvuk
14th May, 2010 @ 11:07 pm PDT

When I first started reading this I thought "aha another planetary gearset".

This is a classic elementary problem in mechanical engineering, which is to work out the output gear ratio of a planetary gear set depending on sun speed (the center gear), planet speed (the one "orbiting" the sun) and ring gear speed (the ring within which the planet rotates). Usually input and output are the sun & ring and the planet just whizzes around, but you can vary the planet rotation and make any speed you want. So long as you have continuously variable speed electric motor driving it, that is....

I wonder why Gizmag doesn't do an article on something truly novel, such as the Ikona gear form?

www.ikona.ca

And they developed a nearly identical CVT concept based on a planetary gear using their non-involute gear tooth form.

Ikona has already gone bust, and all their engineering talent departed, but what's neat about their gear teeth form is that they achieved tremendous gear ratio reduction and near zero backlash in just one mesh using what they call "eccentric inline planetary" gear arrangement. They have a nice video online, too!

Grunchy
14th May, 2010 @ 11:58 pm PDT

Oops..the plumber guy is reinventing the wheel. Literally. Since he has never before learned of them as he himself acknowledges. Surprise surprise.

Obviously nothing really new.

See the comments by Grunchy and NoResponse.

Even if it makes some Gizmag people head spin...come on get some elementary engineering literacy.

nehopsa
15th May, 2010 @ 09:01 am PDT

It appears to me, though, that there is a fundamental problem with the design. "Doesn't use any clutches or friction drive components" -- which unfortunately is not true. Go back and watch the video showing how it works. In order for the transmission to be in 'neutral', both shafts have to be turning at the same speed. Now, imagine that the drive end is connected to an ordinary gasoline motor through a rigid linkage. Start the engine. The driven end of the transmission goes from stopped to idle speed, and the rate of change of RPM as the engine starts is not entirely predictable, so the vehicle is going to lurch forward uncontrollably when the engine starts, with a similar effect when the engine is stopped; even the best designed rotation sensors are going to introduce lag in controlling the gearing motor to spin up/down the drive-ratio shaft as the engine is started/stopped. Now, admittedly, the clutch would only be needed when starting and stopping the engine, but it's not eliminated from the design.

srmalloy
15th May, 2010 @ 09:56 am PDT

This is NOT magic and NOT a solution to variable transmission problem either. This guy simply out sourced the difficult (and yes, without magic impossible proposition: geared variable) part to an EXTERNAL input. There he has his very same problem again. Now he needs to vary the speed of his external control shaft. And I guess he DOES NOT DO IT WITH THIS TRANSMISSION again ad infinity however "variable" it is. It is not. That is the whole magic: external input that the Gizmag writer should have recognized and credited for the WHOLE magic trick.

nehopsa
15th May, 2010 @ 10:27 am PDT

Looks like the entire torque load is sitting on the control shaft motor. The seems like a major flaw unless that motor can put out equal torque to counter it. You don't want load on your control systems. The more it think about it, the more it sounds like an elaborate and obfuscated differential drive. The same simple gear system used in 99% of all today car power trains.

I'll defer to licensed engineers, and trust the the firms he is talking about are real. But from what I have seen the system does not appear to be anything new.

Ben McBeen
15th May, 2010 @ 01:54 pm PDT

This is simply a planetary differential. They're already in the transfer cases of many trucks and SUVs. This is not what he's claiming--- TOTAL BUNK.

winkosmosis
15th May, 2010 @ 02:35 pm PDT

chann94501, thanks for that very informative post about the John Deer IVT, i had not realized it worked like that, I thought it was a toroidal-friction transmission, not the clearly highly developed driven opposition device it is. The fact that they can use the high torque of the hydraulic opposition motor to over-drive the sun gear for higher than 1:1 output ratios is very snazzy. I think this guy's work may be original in it's execution and potential compactness, but it does seem to be a well documented existing idea. I had always wondered about taking power off the planets since the first time I say a Sturmey-Archer 3 speed hub in pieces, but I never pursued that thought, now I know ;)

JawzX
15th May, 2010 @ 03:19 pm PDT

This is definitely not a new idea, neither is it a CVT.

I built an almost identical system over 10 years ago for a telescope tracking drive. There we had a high torque motor running at 60rpm for the main drive that kept all the gears meshed in the forward direction and outputting 1 rev per 23h 56m 4.01s. Then a much smaller control motor added or subtracted corrective motion from on command from the CCD autoguider.

This system could never work as a CVT as all you have done is decouple the main drive by spinning up a variable speed control drive. We knew and found that to get any more than small adjustments in output rate the control motor torque has to be comparable to the torque of the main drive.

On the other hand, if you did have a main petrol engine and a separate high torque electric drive coupled in this way you could use it to run a hybrid while keeping the petrol motor working at ideal revs. You would get massive losses in the electric conversion and the extra gears, but provided you use it sparingly and never drive in the city it could work.

Gary Marriott
15th May, 2010 @ 03:24 pm PDT

HELLO PEOPLE, this "VARIABLE TRANSMISSION" is a JOKE!!!

A variable transmission requires only ONE motor and a CONTROL LEVER (not second motor). The control lever efortlessly controls the speed and direction. This contraption is not a variable speed transmission and as another reader posted, is an overly complex version of the Hybrid drive 'planetary transmission that is in my Toyota Highlander (which has one gas engine, a large generator and large electric motor) and is a variable speed, reversible constant mesh gearbox with no clutches or shifting and accelerates from 0-60 in 6 seconds!

This moron has devised a fancy ring, planet and sun gear arrangement that has two motors feeding into it. There is no variable speed, single motor energy source, reversible transmission here...

It is quite a nice looking Rube Goldberg contraption designed to confuse the mechanically unsophisticated...

The best variable speed transmission I've seen uses swash plates that can be set to different angles producing variable amounts of oscillation on a set of rods that are either hydrualic or feed ratcheting mechanisms. In Wikipedia, the article on variable speed transmissions has an animation and image of The Honda DN-01 motorcycle transmission and is the first road-going consumer vehicle with hydrostatic drive that employs a variable displacement axial piston pump with a variable-angle swashplate. This approach is also used in Diesel truck alternators with a purely mechanical ratching configuration but is not suitable for large torque. As another reader mentioned, tractors have similar swashplate hydraulic CVT's as well.

Nice job GizMag for promoting a fraud. The fact that the guy got on TV does not mean his stuff is real. Get an ME to vet your articles.

Shannon

Shannon
15th May, 2010 @ 04:05 pm PDT

"Still sceptic about the efficiency considering we pop the clutch in split seconds and generaly stay for a long duration at the rev with maximum torque, some apps will be great though."

If you "pop" a clutch and you stay at optimal torque, you're slipping and burning out the clutch. Yeah, lets ruin the car. Great for racing, bad for every day people.

"I agree, I think this is similar to the Hybrid Synergy Drive developed by Toyota which also does not involve any clutch or belts."

The Synergy drive itself doesn't use any clutches/belts, but it hooks up to a CVT that does.

"Looks like a simple differential mechanism to me. Kind of interesting that the control shaft needs to be driven by a CVT!"

No, just an electric motor.

"This transmission is almost identical in operation to a Constant Speed Drive used on aircraft jet engines."

Except the "Constant Speed Drive" system used on Jet engines runs a hydraulic pump which drives a hydraulic motor. It's a hydraulic CVT and those have been around for a long time.

Does anyone know what they're talking about?

As for effencincy, all you have to do is measure power going into and measure power coming out. A quick and simple test could easily be done to see if this drive is even feasible. It would be nice to see this info since it could be horribly inefficient.

Bengie25
15th May, 2010 @ 04:17 pm PDT

Bengie25 - this is *exactly* how Toyota's Hybrid Synergy Drive works. There are no belts, but there are two electric motors. One on the flywheel of the petrol engine and another attached to what this dude calls the "control shaft"

It is effectively a differential with a motor on each end, with the wheels attached to what would be the input shaft on a classic differential.

You can then push the power on the output however you like by changing the control motors speed relative to the power motor (which, thanks to running on petrol, only has a limited speed range to work with).

There is nothing new under the sun.

q: Does anyone know what they're talking about? a: not you, at least.

Luke Smith
15th May, 2010 @ 07:27 pm PDT

Some people consider Durnin to be a genius, some think he is simply mistaken about the potential of his "invention". But I want to note that his model works great with no output load. With any output load, the torque of the main motor has to be equalled by the control motor, as others have noted.

Is it possible that Durnin worked on this (on and off) for 20 years, and never thought to try his model with an output load? I say no. Which makes him -- and I only use the word because it fits (and because someone else already did) -- a fraud.

French
15th May, 2010 @ 09:51 pm PDT

With my limited understanding of mechanics this seems like a dual fly-wheel system. The system, instead of placing the idle friction into the torque converter that this mechanism uses that power to slow itself down. I can see the efficiency gain at the beginning of this device: Full power out of the system during use, and less use of friction breaking systems if/when the external wheel has enough surplus to cancel out the input. Built properly with a breaking recovery system and the savings could be quite significant.

However, gears or not, all substances can break. The more power you need, the stronger and larger the two control shafts have to be. Too small and the input would tear it to shreds. To large and the loopback system would cost more energy than it's worth. They key of course is balance. The same goes for the release of energy from the gear system during rapid deceleration. Too much and the car lurches, to little and you're just wasting fuel.

Stephen Kraushaar
16th May, 2010 @ 12:42 am PDT

There is no flywheel here. Please read p. 19 of the 2008 independent lab report hosted on Durnin's own web site:

http://infinitelyvariabletransmission.com.au/wp-content/uploads/2010/05/dDrive-Transmission-Report.pdf

They state clearly that this device acts as nothing more than an epicyclic gear set, and that it is not a CVT (though it could serve as part of one). It's a pretty decent analysis, which properly notes that it's actually arbitrary which input shaft you call "power" and which "control", since they both require comparable output motors.

With all due respect, I hereby recommend that GizMag admit that this device is a hoax, that they have made a mistake in featuring it, and formally retract the article.

French
16th May, 2010 @ 03:38 am PDT

If this is such a well-known concept, why is there a major company interested in it?

James Pereira
16th May, 2010 @ 03:49 am PDT

I found it really frustrating that the video does not illustrate the back side of the prototype better. First off, I would like to see what controls he had over there - seemed like a lot of buttons for this small demo!

Torben Rygg
16th May, 2010 @ 04:16 am PDT

It is a neat idea but others have thought of it before.

I would not call him a fraud but I don't think that he has done all the math.

Looking at it I would assum that when a load is put on the output shaft that the torque is reflected back to the control shaft. if the control shaft was locked full torque would be applied to the output multiplied by the overall gear ratio of the system.

If the control shaft was allowed to slip then the output would slow down but the effiency of the system would go down because the RPMXTorque of the output be wasted. If that energe comes from the prome mover or some other soucre it ti still wasted.

In the video he applies an RPM to the control shaft but I think that when it is loaded up that he will eed to appliy an opposing torque to the control shaft.

Kudos for building a neat system but is it new and is it a holy grail no.

A hydrostic drive would woulrd but the losses of drving the pump are probably to large to maki it worht while.

If a lightweight electric generator / motor drive is developed that could handle 300 HP

then maybe the math would make sense.

Captain Danger
16th May, 2010 @ 06:23 am PDT

put a electric motor on each axle of a car rearend, use the driveshaft yoke as the 'variable speed output shaft' and save yourself 20 years...sorry, its just a differential that uses planetary gears.

tim c
16th May, 2010 @ 08:01 am PDT

@ Grunchy

Which version of the Ikona transmissions are you referring to? The non-involute profile gears (aka Harmonic Drive) were used on the lunar rover in the sixties, but i have not yet found a variable speed/ratio version. Could you post a link to the actual drive please? Thx

jeffbloggs
16th May, 2010 @ 11:58 am PDT

Humm, the problem he seems to have claimed to solve is now externalized to what the 'control shafts' would be connected to. The sizing and names of the components is misleading. Those 'control shafts' are going to take a heck of a load when there is drag on the output.

This has the feeling of somebody at an inventor's fair trying to drum up money from investors with a little song and dance.

Anyways, I think it's all fine, and he seems fairly honest in what he says. What *bugs* me is the Gizmag reporter (or whatever he is) giving the other side of the sales pitch like a plant in the crowd yelling "Amazing! It's too complex to understand, so let's not try! The scientific world is going to keep a close eye on this! It's a wonderful story of a hands-on blue collar worker coming up with something brilliant! I'm sure he's going to be rich!" Seriously, was Gizmag (or at least the guy) paid to turn this into an obviously biased story?

Fill F. Fill
16th May, 2010 @ 02:10 pm PDT

It seems to me that this gearbox doesn't give you torque multiplication which is the whole point of gearboxes. The additional torque you would have gotten from a low gear ratio goes into the control shaft. If I'm right then it might give you an equivalent first gear ratio but not the normal first gear grunt. So what's the point? I could be wrong but I don't think so.

warren52nz
16th May, 2010 @ 02:38 pm PDT

Sorry folks - this is just another friction-based transmission. That second electric motor, conspicuously hidden most of the time, is supplying the "friction" needed to vary the transmission.

He hits the nail on the head a 9:00 minutes into the video "take power out" - that's what friction means.

Here is how you can re-create his entire envention, without using even 1 single gear at all:

---fixed-shaft---[motor2]-armature-[motor1]-armature-----output-shaft.

(note that motor2 rotates the entire of motor1 itself)

Drive motor1 at a constant speed (same as he is doing in the video)

Drive motor2 at a variable speed in either forwards or reverse (that's what he's doing with the "hidden" second motor in the video, and his motor speed controller box), and the output shaft can go at any forwards or reverse speed you want, including standstill.

If he had though to hook an ammeter up to both motors and a load up the the output, he could have svaed himself $50,000 in wasted patent fees :-(

The fastest way to identify scams or "mistaken inventors" is to look for the missing ammeter (or oscilloscope if they're messing with waveforms instead of constant currents)

christopher
16th May, 2010 @ 07:28 pm PDT

@Luke Smith

It would be nice if only people that know how the Toyota Synergy Drive works would comment about it...It definitely does NOT have any belts or pulleys or cones or hydraulic or any form of CVT in its normal automobile guise. It is exactly like Luke has said, a planetary gear or "differential". And it does not use any type of friction/brake system to control torque conversion at all!! (Buy some Lego if you want to see a differential and how it works guys!)

@tim c

Exactly right m8! Imagine one wheel being replaced with a combustion engine the other by an electric motor. Now start the combustion engine and rotate the electric motor in the opposite direction at the same rpm as the combustion engine...the output on the driveshaft will be zero rpm. Now change the speed of the electric motor and it will change the driveshaft rpm. Spin the electric motor backwards for reverse. This drive shaft rpm will then propel the vehicle (after its connected to a diff etc) as a variable transmission. Add a couple of ratios between the components and some fancy control system and hey presto Prius Synergy Drive

@ chann94501

John Deere did not develop the IVT, it was actually originally developed for Deutz Tractors (Germany) by ZF in Freidrichshafen (Germany) were I used to live

@ anyone who doesn't understand the Prius Synergy drive:

First up physics one on one.... Torque is not the same as power and does not necessarily consume energy.

The easiest way to understand the difference is that torque is without time. However energy is always consumed (read: converted into another form) over time to do work. To explain this I will try to clarify the following:

1. torque can exist in a lever, wrench, nut, bolt etc without it actually moving. Or:

2. a constant amount of torque can be applied to a fulcrum (pivot) in motion. Or:

3. Torque can be varied with the fulcrum in motion

For Example: In the tightened state of a nut the torque exists between the surface of the nut and the body onto which it is fastened, and against the thread of the bolt. A tightened nut/bolt does not do work, however retains its torque, and therefore does not consume any energy to remain in that state (as per point 1. above).

Here an analogy:

I take my son to the play ground and I sit him on one end of a seesaw, and myself on the other. If I remain relaxed he will stay up in the air indefinitely (no work, therefore no energy expended as per point 1. above). However, the fulcrum (ie bolt, pivot point of the seesaw) will experience torque, by an amount determined by my son's weight, due to gravity. When I lift my own body weight (or "I work" for which I consume energy over time as per point 2. above) the amount of torque applied to the pivot is still the same (apart from the change in lever geometry in relation to gravity). This will continue until my son touches the floor, at which point the torque exerted on the pivot will decrease until I no longer sit on the see-saw.

This same effect can be achieved with a rotating planetary gear as is used by the Prius. In this scenario imagine that I am the Prius combustion engine (also the one doing work converting energy over time) and my son has a variable length arm on his side of the pivot, which is in effect the electric motor/ratio controller. Varying the length of the arm my son is sitting on will not expend much energy, but the effect of his position will determine how high or low I am on the see-saw and how much work I must do to lift (or acceleration by adding energy) or lower my son (deceleration or in the case of the Prius regenerative braking). My son varying his see-saw arm length will control the amount of torque applied to the pivot by my weight from 0-100%(as per point 3. Above). This is similar to the torque control effect of the Prius Synergy Drive and most likely the dDrive. If it is engineered correctly it can be very efficient, but torque does not necessarily affect the energy efficiency of a transmission as it has little to do with work and the conversion of energy. The only time it can affect a change in a systems efficiency is by optimising the input devices torque range to the output torque load. For example: to convert the poor useable torque range of a combustion engine to the high torque requirement of spinning a wheel to propel car. Simply put: Transmissions only convert torque by changing the length of the lever (even in a planetary gear), and therefore can be used to change the force applied. They do not and cannot increase/decrease energy conversion (no perpetual motion machine here!) and will generally increase entropy through friction at the fulcrum.

Archimedes said: "Give me a lever long enough, and a fulcrum to place it and I could move the world". So take note of my pop culture wisdom: no matter how fancy a transmission is it can only succeed in moving the earth, but it will never change it ;)

The other thing I would like to add here is that the Synergy drive can furthermore increase its efficiency by reintroducing the electrical energy "absorbed" through controlling the ratio, by the smaller generator(7kW) into either the battery or main electric motor (50kW) or vice versa, all the while optimizing the fuel consumption of the 57kW petrol (gas) engine. It can also optimize the regeneration whilst braking using the same mechanism. The electrical system efficiency is generally over 90% for AC motor/generators with inverter control and is not that great a loss considering the optimization of the engine speed/load and fuel consumption. Don't forget the Prius also utilizes this same system to control and reduce emissions by varying the load on the engine together with variable valve timing (compression ratio), fuel injection and ignition timing. BTW the Prius always starts warm, by using the built in thermos for its coolant, and always at the required revolutions using the generator (typically between 1500-3500rpm, never 150-300rpm like normal engines) which reduces the emissions and also the wear on the engine. One cold start at -15c is like driving a car up to 500km for wear on the engine. Also, less oil is burnt because the piston rings are expanded fully as they are at temperature and therefore completely sealed. Please note that clean combustion of a fuel is not directly a result of efficient combustion, and all these things need to be considered when constructing a "greener" vehicle from a manufacturing point of view.

There are numerous other side-effects that I could mention in relation to the Toyota Synergy Drive but I think one thing should be clear by now: Before anyone makes a comment on how good/important/revolutionary/genius something is or not, they should consider the overall benefits/detriment of any system by informing themselves first!!!

After all, that is why God invented Google ;)

BTW if you really want to use something efficient for transportation apart from a Prius...

try walking... a 10" wheel requires 360° of angular motion to cover 80cm, a human step only about 44° and all the other benefits this system provides are incalculable...someone obviously had their thinking cap on when we were made....

jeffbloggs
16th May, 2010 @ 09:19 pm PDT

I've only seen the bottom shaft rotate the opposite direction from the top shaft. And now I'm wondering what would happen if the bottom shaft was made to turn the other way around, so the same direction as the top shaft... Would it speed up the top shaft, generating extra power?

If that's the case, then this guy has done a lot of work to make a complicated equivalent of something much simpler: the differential!

BoilingOil
16th May, 2010 @ 10:47 pm PDT

These people who appear on the New Inventors here in Australia have their inventions well covered with patents etc before appearing. You don't get patents if the design is already patented. We will see if it really works when he shows his full prototype. Great work and smart design although if we were really looking at pure electric vehicles we don't need gearboxes see the hi-pa drives, in wheel electric motors for the 21st century. The Brits are way ahead even converting the F150 ford yanktank to electric with 600hp see: http://news.pickuptrucks.com/2008/10/updated-hi-pa-d.html

greytoma
16th May, 2010 @ 11:43 pm PDT

This is definitely why I like Gizmag! You find what everybody searchs for!

Unless there is no more energy dissipated in the double gear, this is a wonderfull invent. Gear up for the plumber inspector!

Ariel DAHAN

Attorney at Law, IP law, Paris Bar

Ariel Dahan
17th May, 2010 @ 03:34 am PDT

Whoa, hold it. The application goes to bits as soon as the "eccentricly mounted gear" starts to spin around at top speed. Vibration, it seems, without counterbalance will result. Another Gold Coast con man? I think not, but a system that might be useful at low speed application...maybe.

j.gates
17th May, 2010 @ 12:21 pm PDT

This looks like a great solution when coupled with a hydrostatic drive to set speed. Perhaps a bit Rube Goldberg in concept but with refinements could be extremely practical in many applications

ab72756
18th May, 2010 @ 09:36 am PDT

I am sad to see so many people (including the inventor) believing in this device. It reminds me of when my dad used to try to build a perpetual motion motor with magnets. This device is just transferring (ie hiding) all the transmission problems described to another place so they look like they're gone, but they're not resolved at all. As someone observed in the earlier comments, the device is essentially a differential. You could lift one of the back tires of your truck off the ground and argue that by changing the rotation of this floating tire, you vary the gear ratio of power transmitted from the engine to the wheel that is still on the ground. Think about it. It wouldn't transfer the energy the way you want it to even though you might be able to get the desired relative rotational speeds. Another way to look at it is mathematically. An ideal gearbox will have a ratio R such that output speed = input speed * R, output torque = input torque / R, and output power = the product of these which is the same as input power. This makes sense, because it means that energy is fully transferred; it is neither created nor destroyed. If you attempt to use an ideal 1:2 differential as a CVT, output torque (on both sides, regardless of speeds) = input torque, and left output speed right output speed = input speed. Output power = the product of these which again is the same as input power. Do the math. The reason it's not a variable transmission is because it can never change the torque ratio between the input and outputs. Sure, you can vary the output speed on one side of the differential by adding or removing power from the other side, but that just means you would need a CVT for that. So alas, the problem is moved just beyond our sight and grasp and we imagine that it is solved. Sorry to be so blunt, but you can mark my words: this invention won't go anywhere.

mech_engr
20th May, 2010 @ 05:40 pm PDT

This is definitely not an IVT. It is a PSD; a Power Splitting Device or Power Sharing Device. An IVT uses only one input to provide one variable output that can be adjusted continuously down to zero speed, whereas this uses two inputs for a variable output. The editor/writer needed to do research before he wrote this article! Look up 'Infinitely Variable Transmission' in Wikipedia. Misinformation like this should not appear as an article that will be assumed as authoritative!!! Get your facts straight!

IVT Inventor
5th June, 2010 @ 09:24 am PDT

This looks like a mechanical transistor to me.

I agree with BoilingOil in that it is a differential.

I hope something comes out of this.

MondoBanana
22nd October, 2010 @ 07:06 am PDT

I need compact axle units for my Famiglietta design : http://www.hermes-pegasus.biz

Algreen-ussing Søren
11th December, 2010 @ 06:06 am PST

What a scam...

Its nothing different than what's in your average hybrid (Toyota or ford fusion).

What is "the catch"? You have to spin the planetary gear with that electric motor (Just like a hybrid car). The problem is that that electric motor has to be comparable in power to the main engine, and that electric motor has to vary in speeds, in effect being a continuously variable transmitted source of power to begin with... Doable somewhat with electric motors, but then... why not throw away the transmission and the other engine and just drive the wheels directly with the electric motor? Or if your goal is to store and release electric energy while running a gas motor at a constant speed for fuel economy then you've just built a prius or ford fusion... There's nothing new here with this design... It smacks of perpetual motion machine announcements, praying on those not technically inclined, and typical of those comes from some far off place-with-attitude like Australia, some place where the locals can be convinced by the line "Local boy is smarter than the rest of the world and creates what the "big boys" have been trying to make for years, come support him with your cash for his business!"... reminiscent of some Irish or Scottish corp (i forget which) that recently was pushing it's perpetual motion machine. One of the key statements by such a company is "Its been checked out and vetted by engineering company X".. this should be an alarm bell to warn you to get far far away. If the device was useful and revolutionary as advertised, they wouldn't need to get any engineering company to check it out, they'd just either sell the patents, or build a machine that would make them rich. GM or Ford would snap up something like this if it was real, but they'd have their own tech guys check it out, and they'd see it for the scam it was, or if it was real then GM or Ford would buy or license it in a second. The only purpose having some 3rd party check it out supplies, is to try and persuade some segment of the public into believing the legitimacy of the product in order to scam them out of some money they might invest in the company/product... Lets be clear here, that's the only value to the "inventor" - to scam the gullible public into investing in them. It's useless to industry... Hence hiring some engineering company to lie about how useful the product is.

It's a sad statement on humanity.

The question I have is: Why does gizmag continue to post articles like this? A while back they posted a perpetual motion machine. Do they realise the disservice they do to any perspective investors that might read this article on their site (and skip the comments) and use that as the basis for investing in this scam? Does Gizmodo get paid to run these types of articles? Please clean up your act Gizmodo.

Dan K

Dan K
24th December, 2010 @ 02:19 pm PST

The demo set has been around since 2010.The invention of gear transmission success or not are depend on gear-set build up, the capable of part to handle torque and strength, sometime we can just link-up a set to perform said work but unable to assemblies it into high durability set, due to constrain of space.This is my word to Mr.Steve Durnin, perhaps it time to think out news version D-Drive 2.0

Tw Tan
9th February, 2012 @ 10:51 am PST

I have a real CVT (big torque) with no friction:

http://yves.maguer.free.fr/home/CVT_fort_couple.html

A real CVT must have (only):

_ one rotary input

_ one rotary output,

_ a cursor to command the ratio.

yves_mag_cvt
30th July, 2012 @ 02:27 am PDT

I explain how it works here:

http://yves.maguer.free.fr/home/CVT/To be or not to be a CVT.html

It is NOT a real CVT, Sorry!

yves_mag_cvt
12th November, 2012 @ 06:09 am PST

bad link, try this:

http://yves.maguer.free.fr/home/CVT/To%20be%20or%20not%20to%20be%20a%20CVT.html

yves_mag_cvt
28th November, 2012 @ 06:15 am PST

The comments by the foregoing pundits are all very well, but if battery technology and direct sun energy use make the kind progress they are likely to in the near future, it will not be long before the ICE motorcar is a dodo. Electric vehicles are the future, how ever much we try and deny it. They need no gearboxes, merely clever control of the drive motors.

I am working on a vehicle so light and space-efficient that battery life will not be an issue, especially when batteries using the new wonder material, graphene, are in production and battery life is ten times what it is today.

The future is electric, guys. No gears; no clutches; no torque converters; no engine maintenance; no cooling systems; no lubrication systems. All costly, unreliable, material wasteful, noisy, dirty and so last-century. With electric, just put your foot down and go!

Mike Franklin
15th April, 2014 @ 05:22 am PDT

electric motors need gearboxes!

if we think in ... POWER available.

an electric motor produces its maximum power at rated speed, not low speed!

So the CVT gives the maximum power of the engine at low speed of the vehicle!

yves_mag_cvt
28th May, 2014 @ 03:50 am PDT
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