[olePigeon]

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

Wow, this is really cool. Apparently he also won some show I'd never heard of on NBC. It's an infinitely variable transmission. In short, it is always at peak gear to power ratio regardless of the speed of the engine. Because it's infinitely variable, you don't need a clutch, and because it uses clogs and not a wheel or belt system, you get optimum power and torque. Torque is simply limited to how large and how strong you can make the gears.

I'd love to see this guy get an interview on Top Gear.

[mduell]

Note all the demos are at low speeds... for real implementation I'd have concerns about vibration and durability of the pinion.

[olePigeon]

Originally Posted by mduell 

Note all the demos are at low speeds... for real implementation I'd have concerns about vibration and durability of the pinion.

Absolutely, but I'm anxious to see a full size prototype working in a car. He mentions he has a few engineers looking at it, and in principle it looks like it should work. At the very least I could see it being used in construction vehicles and long haul vehicles. This thing could do wonders in terms of fuel efficiency and longevity of engines for trucks with heavy cargo.

[Sealobo]

holy shit.

[Andy8]

Originally Posted by olePigeon 

Apparently he also won some show I'd never heard of on NBC.

New Inventors on Australia's ABC (The Australian Broadcasting Corporation).

[Shaddim]

That's nice, but I still prefer a manual.

[reader50]

This is what patents are supposed to be for. I hope he gets rich from it.

And oh yes - I want one.

[macaddict0001]

Wow he almost had me fooled, but I looked at that thing real close and it just won't work.

(Disclaimer: Everything I say is my opinion. Unless I quote references)

[turtle777]

Is it MAC compatible ?

-t

[Eriamjh]

How do they control the speeds of the two shafts? That's what I want to know.

[reader50]

Of the two shafts, the top one carries the drive force. The lower shaft is the control input. There is a 2nd smaller motor powering the lower shaft. It is on the far side of the demo unit, facing the inventor. You can see it in a few shots, mostly when the camera shows him operating the control board.

I may have spotted one problem with the design. When the control shaft is overdriven, so the final output is in reverse, the driving shaft on top comes to a stop. This suggests that in the reverse condition, the motive force all comes from the control input.

If true, this is not ideal. The control motor would need to be fairly beefy to handle Reverse in a car. The purpose of all the gears is to provide variable output ratio, and to isolate the control shaft from the load torque. Which it appears to do in forward & neutral, but not reverse.

It might not work this way if there were a load on the unit. Which they couldn't simulate unfortunately - the demo unit has a fair number of plastic gears.

[Cold Warrior]

I read some of the comments on the page and they were really nasty and putting down this invention. From our knowledgeable members, does this thing look promising?

[macaddict0001]

It looks to me like the bottom shaft torque input has to match torque output, but its a visual mess so its hard to say.

[mduell]

Originally Posted by Eriamjh 

How do they control the speeds of the two shafts? That's what I want to know.

Small electric motor; they just need to control the speed of the control shaft, the torque/power is minimal.

[DrTacoMD]

Does it run Linux?

[SSharon]

Originally Posted by Cold Warrior 

I read some of the comments on the page and they were really nasty and putting down this invention. From our knowledgeable members, does this thing look promising?

This isn't my area of expertise at all, but my guess is that even if this isn't the holy grail of transmissions (and I don't think it is) it will get people to rethink our current transmissions and hopefully develop something new. Even if this guys product fails initially I'm sure the kinks can be worked out and learned from and applied elsewhere.

[downinflames68]

Originally Posted by reader50 

If true, this is not ideal. The control motor would need to be fairly beefy to handle Reverse in a car. The purpose of all the gears is to provide variable output ratio, and to isolate the control shaft from the load torque. Which it appears to do in forward & neutral, but not reverse.

Not really. Accelerating at the speeds most people back up in would only require like 1-5 horsepower, which can easily be done with an electric motor.

[Eug]

Originally Posted by olePigeon 

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

Wow, this is really cool. Apparently he also won some show I'd never heard of on NBC. It's an infinitely variable transmission.

D-Drive redux: about that holy grail thing...

Firstly, the D-Drive as pictured in our video is not a complete infinitely variable transmission system. At best, according to the engineering report, it is a cheap, innovative and potentially very useful primary component of an IVT.

The key problem here is that the D-Drive's control shaft needs to be driven at variable speeds in order to effect the final ratio - so effectively, you need a variable drive motor attached to the D-Drive before it actually works. e3k's engineering report goes so far as to say the control shaft could foreseeably be driven through an external CVT, using a clutch - which of course introduces not one, but two friction components to the system.

P.S. I drive a Prius, and have been for almost 10 years now.

[downinflames68]

Priuses are lame.

[mduell]

Originally Posted by Eug 

The key problem here is that the D-Drive's control shaft needs to be driven at variable speeds in order to effect the final ratio - so effectively, you need a variable drive motor attached to the D-Drive before it actually works. e3k's engineering report goes so far as to say the control shaft could foreseeably be driven through an external CVT, using a clutch - which of course introduces not one, but two friction components to the system.

Why not just use a small electric motor? All you need is to set speed, not provide much power.

[Eug]

I am not an engineer. Here is the engineering report:

http://infinitelyvariabletransmissio...ion-Report.pdf

[olePigeon]

Originally Posted by Eug 

P.S. I drive a Prius, and have been for almost 10 years now.

Maybe your next car will be a Vokswagen TDI. It's faster, more powerful, better looking, and gets better gas mileage.

[Eug]

Originally Posted by olePigeon 

Maybe your next car will be a Vokswagen TDI. It's faster, more powerful, better looking, and gets better gas mileage.

Not really, since the TDI is diesel. As you know, diesel fuel isn't regular unleaded gas - different energy content (about 18% higher), and higher emissions. I did look at the VW Jetta TDI at the time , but the car is also quite a bit smaller, with crappy storage in comparison. This is the #1 point for me. And where I live, you have to search for diesel stations - it's very, very annoying. I found out the hard way after renting a diesel U-haul truck.

Anyways, the point was is that the Prius has had a CVT transmission with no belt or clutch since the 90s, in production cars. Different of course, but just an added point for the discussion.

And like I said, I am not an engineer.

[reader50]

Originally Posted by mduell 

Why not just use a small electric motor? All you need is to set speed, not provide much power.

The control input is not isolated from the load. The dDrive has 4 connection points labeled In, Out, Control1, and Control2. Under certain conditions, it can demand up to 50% of power input from one or both of the control inputs. It depends on the desired gear ratio. I'd recommend reading that report PDF - it was quite interesting, and the engineer obviously likes the dDrive.

A hybrid already has a beefy electric motor, and will benefit from the dDrive. A 2-motor car needs a common gearbox anyway, and the dDrive eliminates the need for the clutch & 2nd gearbox to provide Neutral and Reverse. So you get the benefits with no real cost.

A full electric vehicle can use it too, by using 2 medium-sized motors instead of one big one. You obtain better torque control using less expensive motors, and save on the solid state motor control box. Probably worth it overall.

In a single-engine car, you'd need to split the engine output, and use a conventional CVT to drive the control inputs on the dDrive. There may be no weight savings overall, the extra CVT is likely to offset losing the clutch. The improved efficiency might be worth it, and the controls CVT would only need to handle half the engine horsepower vs doing transmission duty directly.

[Doofy]

Originally Posted by olePigeon 

Maybe your next car will be a Vokswagen TDI. It's faster, more powerful, better looking, and gets better gas mileage.

Or a Ferrari 599. Much faster, much more powerful, much better looking, and who cares about mileage anyways?

[The Final Dakar]

Durrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr rrrrrrrr