D-Drive Infinitely Variable Geared Transmission

**Warr** · 17th May 2010, 22:36

From Slashdot . . looks pretty awesome. No clutch needed, forward & reverse.
Could easily replace automotive transmission systems in the future.

"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."

**Slyer** · 17th May 2010, 23:08

Muchly looking forward to seeing how this develops.

**bogan** · 17th May 2010, 23:11

interesting, it seems to boil down to a planetary gearbox with two driven and one output shaft to me though, which suggests a lot of torque is required for his gear variation shaft.

**Slyer** · 17th May 2010, 23:24

http://www.gizmag.com/d-drive-redux/15120/
Less excited now...

**Warr** · 17th May 2010, 23:36

Originally Posted by Slyer

Less excited now...

For sure !!

What you got right

You can certainly rely on Gizmag readers to think through an issue like this one - some of the technical discussion in the comments section of the original article - as well as the discussion threads on Slashdot, Reddit and elsewhere - was fascinating.

The D-Drive does indeed operate as an epicyclic gearset. It does indeed operate in a similar way to the Hybrid Synergy drive on the Toyota Prius - and this is a matter of some pride to Steve Durnin, who designed it with none of Toyota's considerable resources behind him.

It does require an external CVT or some other powerful drive component for the control shaft that will not yield to the torque of the primary input motor.

So where does this leave the D-Drive?

More or less where the engineering report concludes. The D-Drive is an innovative component that could be used in the design and manufacture of a true IVT for use in vehicles or anywhere else a variable drive would be required.

It's not a 'holy grail' and there's no rabbits coming out of hats - and what's more, it can't forseeably operate with no friction components between engine(s) and wheels, or at least something like an electric motor that can be smoothly varied in speed.

The D-Drive should, and will, be evaluated on its abilities inside this scope - and as such it may well still become a very valuable piece of intellectual property for its designer.

Thanks for calling us out

So thank you, astute readers and commenters, for calling bunk on this one. We saw an interesting and remarkable piece of emerging technology that hadn't been covered yet in enough detail to generate discussion. We certainly generated discussion, but we got some key information wrong - for that, we apologize.