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

It is nothing like the HSD.

It is a complex setup to vary speed in positive, neutral and negative directions. It does not multiply torque or the speed of the engine.

 

Actually the principle is very much like the HSD, but with more
parts, and so far nothing to account for the substantial amount
of power that's going to be sent to those two silly little
bevel gears. Running things like this with little motors is
one thing, but when you actually start wanting to put some real
power through the thing the whole game changes. The idea of
"catching" some of that power electrically and sending it to the
other shaft-control motor is, in fact, *exactly* how the HSD
works in steady-state when there's no battery current in or out.
The power sent through that "electrical hop" is not trivial, so
it has to be handled in a meaningful and efficient way.
.
_H*

 

As I watched it, I saw a great many forces that were not balanced on the centerline. As you scale this up, it will push sideways (nonproductively) a lot. There were bent shafts which will be hard to scale.

This is not insurmountable, belt CVT transmissions started small and grew as it's problems were solved, but I bet that automotive sized uses are not the first use.

Lawn Mowers > Golf Carts > Kei Cars > Cars > Trucks

 

about that holy grail thing...

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.