I see many auto maker especially Toyota switching to a CVT that some car reviewers ( Edmunds etc) seem to hate. That could be that old school transmissions are more attractive to car enthusiasts whereas the CVT is just fine for the typical commuter.
What is the difference between these two, reason. For the switch and should CVT be avoided?
In: Engineering
CVT has a different ‘feel’, which people used to climbing through the gears find disturbing. Also early attempts at CVTs were prone to premature failure, although I assume that’s been fixed by now.
A lot of it has to do with how the car feels and sounds. With discrete gears, you can hear the engine rev up as you accelerate, there’s a pause between gears, then it repeats. A CVT has no discrete gears, and can essentially accelerate the car by holding the engine speed/RPM steady and changing the gear ratio upwards instead. You just apply the gas and it’s a pretty smooth acceleration even up to highway speeds. (Source: i rented a CVT car for a week once)
Being more in control and feeling the behaviour of the car is “more fun”, but a computer controlled CVT will do wonders for fuel mileage while still being pretty good overall. That’s definitely what the “typical commuter” wants. Whatever the optimal gear ratio is, a CVT can provide it while the manual or automatic must choose which gear from a list is closest.
The only concern I have is the longevity and reliability of the CVT. They’ve been around for 15+ years which is pretty good, but I’m not sure about how often they need repairs. But this is my knowledge gap. Classical automatics may need a rebuild after a long-ish period of time, and manuals are almost maintenance-free other than oil changes as long as the clutch doesn’t wear out.
I used to drive a scooter which had CVT (described at the time as “twist and go”).
It was fun to ride – no gears to change, and no feeling of jumping between gears like on an automatic car.
Much easier to ride than my motorbike, with a manual gearbox.
My only concern with a car that had CVT would be in fast, immediate acceleration when required. Without the ability to “drop a gear” for a sudden necessary burst of speed, you could feasibly not be able to nip out of trouble when needs be.
Cvt has to wheels and a belt. The wheels can use air or hydraulics to change their diameter. When they change the ratio can be almost infinitely adjusted so there’s a ton of “gears”. I say “gears” becuase they aren’t actually gears just different ratios.
The upside is that is is super economical since it can be at the most efficient ratio for fuel mileage all the time. Fixed gears cannot accomplish this.
It is also very smooth there are no clunky downshifts so it makes for a very smooth ride.
Jatco ruined their reputation with some poorly designed units, but most of the ones you will find today are very reliable.
Some manufacturers made them have fake shifts to seem more like traditional automatics which completely defeats the purpose but helps buyers feel more comfortable with something they know.
I was skeptical at first but really love my cvt. They are not engaging like a manual but they are good at what they are made for
A normal transmission has a finite amount of preset transmission ratios to choose from.
A CVT has a range of transmission ratio and you can select any ratio within the range, effectively “infinite” amount of gears.
This allows CVT to precisely choose the best transmission ratio for a given speed and load instead of hopping between ratios and run the engine less than optimal to cover in between, resulting in better fuel economy.
However CVT uses a metal friction belt/chain to transmit power, this creates a few issues.
* The belt may slip at high loads, so the highest power a CVT can transmit is limited, limiting them to mostly commuter cars.
* The belt is weaker than gears and may snap if the transmission control runs away and apply too much clamping force, making the CVT more delicate than other kinds of transmissions.
For these reasons CVT is limited to economy cars even though in theory it’s the best kind of transmission. Exceptions exist but are pretty rare.
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