Automatic Gearboxes

facade

All "modern" manual gearboxes have dog teeth (so they are dog gearboxes), the outer of the synchro hub slides onto them to lock the gear to the output shaft (first rubbing the brass cone against the gear to hopefully accelerate the input shaft and all the gears to the required speed- they have a very hard life!).

Is the Renault just a motorcycle gearbox, without brass synchro cones, and the controller just bangs the sliding selector into mesh when the speeds almost match?

Over 40 years ago I worked for Lucas, and we were looking at automated truck gearboxes that worked like that- 

on an up change the ecu backed off the throttle, then snatched the gear out as the load came off, and banged in the next gear as the engine speed dropped to within a few RPM of the gear speed.

Down changes it throttled up/backed off to snatch the gear out, then throttled up if required to match the engine speed to the lower gear and banged it in. It only needed the clutch to get moving.

Fairly trivial nowadays. The advantage being the gearbox is a lot cheaper, and the dogs can be larger, which are cheaper to make and claimed to be stronger (It depends on the total contact area surely?)

Goudy

facade said:

Is the Renault just a motorcycle gearbox, without brass synchro cones, and the controller just bangs the sliding selector into mesh when the speeds almost match?

Yes and no.
There no clutch or synchros and as you say it engages the dogs, just without the bang.

There are two electric motors involved, one of which, the starter/generator motor is used to match the gear speeds and mesh the gears smoothly.

As there's no synchros, the gears have less power sapping drag on it, so it's much more efficient than a gearbox with synchros.

Also the traction motor has what is in effect, a two speed "gearbox" of it's own, added to the "Dog" box which has 4 speeds, this creates a lot of different gear permutations.

When you consider it's capable of EV, petrol and petrol & electric drive and all the different "gear" permutations, it has the ability to select a ratio as efficient as possible no matter what's driving it.