One for fans of ingenious mechanical designs

It’s very clever and being able to eliminate the clutch is innovative but there are new engine and transmission designs popping up all the time on YouTube that never make it to production. With the move to EVs I can’t see any car manufacturer investing money in it.

We only have gearboxes and clutches in cars because of the limitations of the ICE. Maybe it’ll have a future in bicycles?

Tim

I designed a constantly variable differential gearbox back in 1957, but nobody was interested. It was designed for a Jowett Jupiter.

But do you really think this is the end of the ICE? Bless!

Even an electric motor has a peak efficiency curve

The Ford CVT for hybrids (licensed from Toyota I believe) is also geared, with no real clutch. And it combines electric and ICE inputs.

A bit different because it relies on the electric motor to alter ratio.

And it's 258MPH without a transmission, and only using a final drive gear set. A lot of other consumer BEV can't do near that kind of speed, using the same concept (no transmission). Tesla did one, where the extra top speed came from designing an electric motor with higher revs (higher centripetal limit, different materials) than the previous car in that line.

The problem with the other BEVs then, is "they're just cheap". They're designed for a different future.

Paul

In practice, current EVs all(?) manage without a gearbox. There's an obvious saving in cost, weight, and complexity.

Plus, there are mechanical losses in a gearbox, so you'd have to show that by running the electric motor more efficiently that at least offsets the gearbox losses and extra weight.

Do they? I am not so sure.

Gearboxes around 98% efficient. In a BEV its the motor and the battery you have to cool...

A stalled electric motor is 0% efficient.

At optimal speed it may peak at over 95%.

Its peak power RPM and current is radically different from its peak efficiency RPM and current

There is at least one with a two speed transmission.

During non-race activity, it always stays in low gear. (Street legal speeds are all covered by low gear.)

Only on the autobahn, would you barely make it into second gear on the thing.

I have not heard of any transmissions with more speeds than that, on a muscular BEV.

The purpose then, of the two speed transmission, is to reach the speed-limiter speed that is advertised for the vehicle. Which is not normally needed. It's not like you are going to hear the car shift, all that often.

Paul

The genius thing about the Prius 'eCVT' transmission is how simple it is. Two motors, a sun and planet gear arrangement, and an engine. No clutches, no belts, basically nothing to go wrong. That's why they can easily get

Toyota perfected it in the Gen2 Prius, some later models have stupid reliability issues unrelated to the transmission - eg the 2010-12 have head gasket problems with the new 1.8l engine, which they fixed in the 2013 year onwards. There's a collection of other Toyotas that either have the Prius system (mostly good) and a few other attempts like the Alphard where it didn't work so well:

Weber Auto's channel is great for understanding transmissions and EV systems.

Theo

TNP is the dinosaur gazing up at the comet flashing across the sky saying “Quick, make a wish!”

Tim

Such a shame that Toyota then decided to woo the petroleum king and pursued hydrogen instead of capitalising on their early lead in electrification.

Tim

I got most of my knowledge from Weber Auto!

And you are the newborn lamb looking at the wolf and saying 'Nice to meet my future'

Unlike Jaguar, they will still be in business in a few years