Helmar

In various reviews, some reviewers talk about the "TRUE" CVT on the LS600hL, while others imply only a perceived CVT: " ... uses planetary gears in a super-smooth system in which the switching among eight gears is imperceptible ...". This quote was from http://www.newcarpicks.com/index.php...tory_id=232526

So which is it? Is the transmission truly continuous with artificial points for manual switching, or is it a modified gear system with the perception of CVT?

Anyone know?

HBH

PhilipMSPT

iTrader: (5)

It's a "Dual Stage Electronically Controlled Variable Transmission (ECVT)."

In other words, they pair the 8-speed tranny with the hybrid's "throttle" to move the gears seamlessly without any interruption to linear driving.

Johnny

From a purist's point of view, it still is a geared (albeit planetary), so there's some shifting going on.

The generally accepted "true" CVT is in fact a belt & pulley system, and its origin can be traced back to Leonardo Di Caprio (aka Da Vinci).

You can read about the various CVT types here: http://en.wikipedia.org/wiki/Continu...e_transmission

Summarizing the Lexus approach:

Helmar

I guess I don't get it.

So Lexus is being untruthful when they say that the LS600hL has a CVT?

It's just an ordinary 8-speed transmission with extra-smooth shifting due to a link with the electric motors?

HBH

Nextourer

no no no.

It's a CVT (planetary gear set). The manual mode "simulates" 8 gears (just like how the Murano's CVT has a manual mode that simulates 5 gears or how the GS450h has 6 virtual gears).

Johnny

Not trying to split hairs here, but Toyota calls it a "Electronically controlled continuously variable transmission (ECVT)", not a CVT. Some industry writers have latched on to the latter terminology. In reality, it is a Power Split Transmission (PST). The end result is "similar" (technically), however it can't be termed as a pure "infinitely variable" system, unlike a belt & pulley system. By the way, a planetary gear setup is a lot more durable and low maintenance on a car whose dynamic loads fluctuate greatly.

Helmar

Ok, as a retired software developer, I guess I'll just have to be content with the old joke:

How many programmers does it take to screw in a light bulb?

None, that's a hardware problem.

I'll be interesting to see how it feels and performs compared to the LS460 8 speed....

Especially to see if the downshift hesitation problem still exists. The only negative in both the 460 and 460L was the same complaint I had in my '03 LS430. When you're going around 30-40 mph, and press the accelerator to the floor (passing, or on an on-ramp) there's a 1-2 second hesitation before downshifting, which is very disconcerting.

Hopefully, with a new transmission, it won't be on the LS600hL...

HBH

Johnny

Or as an Engineer, the joke was stack all the engineers in this world, head to toe, and you'd never reach a conclusion...

Nextourer

With a CVT (PSD or cone/belt), there won't be a hesitation because there's no need to downshift. Just punch and go. The only time you'll have a "hesitation" is if the engine's off and needs to be fired up (i.e. you were driving in EV mode and for whatever reason needed to accelerate hard)

Helmar

There's in interesting tutorial about the Lexus planetary gearset system here:

http://www.lexus.com/lexus-share/demos/Tutorials/planetaryGear/index.html