For the mechanically interested out there: Steve Durnin’s ‘D-Drive’ infinitely variable transmission.
Not being an engineer, I don’t know what else to say about it, other than – pretty neat! Well worth a look…
The underlying principle is one of those things which is dirt obvious once somebody shows it to you. But I’d never have thought of it in a hundred years myself.
I can see the large moving eccentric parts would be an obstacle to smooth operation at any meaningful RPM.
But the idea of a continuously variable, zero slip, always engaged gear train is bound to have some uses. The fact that any failure in the control shaft leads to the transmission going into “high gear” not neutral, means it fails in a very not fail safe manner. That aspect will need some compensatory engineering in the surrounding systems.
I haven’t watched the video, but based on the description and pictures it looks like it’s based on a double differential drive with an electric motor as one of the inputs. If I’m right it might be a new use of an old techology, but it’s nothing revolutionary.
One thing mentioned in some of the commentary I read that might be new is that the D-Drive’s operation is continuous from reverse -> neutral -> forward, whereas others go only from neutral -> forward. Also, other designs make use of a clutch somewhere in their operation, just not with fixed gears.
Again, I’m no mech-e, so I don’t know whether that’s true or accurate…just mentioning it.
They buried the lead. The real application would be in wind generation for constant RPM to the generator from the blades.
Looks promising!
It just looks like a complicated differential, to me. You have to put mechanical power in at a range of speeds on the extra shaft, which is the thing this was supposed to accomplish in the first place. Like Grumman says, it might be useful, but it’s not new and isn’t a variable ratio transmission, is it?
He just reinvented the Toyota Prius transmission. Here’s a graphic model you can control to see how they do it with 2 electric motors and one ICE (internal combustion engine) tied into a planetary gear set. And yes, it’s infinitely variable.
It’s infinitely variable, but it isn’t a transmission, in the sense that it doesn’t transmit power from one shaft to another. It transmits power between several shafts. Or am I misunderstanding?
Reminds me of a torque converter.
There is a system around that does this, its just that it isn’t mechanical, you run a generator are a constant speed, and vary the output by changin the generator excitation, the output of the generator is then sent ot electric motors.
When you demand more power, it simply takes in more fuel, but the engine revs do not change, well not much anyway. Its the principle used on Diesel-electric trains.
I would like an opnion here by Una
Here’s a video of another transmission that sound promising.