Why CVT's are awesome

[LD1]

A local guy just had his 2013 Outback CVT fail (Subaru is one of the few that doesn't have a class action lawsuit - yet, at least). He was quoted $7,000 for a replacement.

Probably not much different than a manual or automatic transmission (if those were an option) in that vehicle.

Transmissions are expensive, especially if having a dealer do a total replacement. Dont matter weather its an auto, Manual, or CVT.

 

[ovrszd]

Hydrostatic is cheap and proven. CVT is likely still more expensive and do all trans shops work on them? I wonder what the failure parts are.
So yes, for a bottom of the line Kubota UTV one should not expect a sophisticated car like trans.
And to cut cost Kubota would not use a trans more expensive than a hydrostatic, so my belt drive makes sense.
But an infinitely variable transmission that keeps the engine in an efficient power band without roaring away like a metro bus
sure seems like an attractive idea.
Regardless of how Kubota's belt drive variable trans works, it is smooth and has no problem with putting the power down. Never had it bog or die on me.
Never had a burning belt or any odor at all, or squeal. Only grinding on shifting and a throttle and brake layout that has cables making some strange bends.
I'd give the trans a B. Not very sophisticated, even less now that I know how it works, but it does work. As i would expect a Kubota to frankly.

A car CVT trans can't be too expensive or they would not have brought it out first on economy cars. I guess they could only handle so much power to begin with.
I think they are now up to the high 200's in max hp to a CVT. Nissan has been using them for a long time and now their Maxima uses one I believe, so that's close to 300hp. The Germans all use dual clutch automatic boxes, most high performance cars do today I think. For faster shifting.
10 speed transmissions now. I wonder why not just go CVT unless they are catering to traditionalists or the CVT's can't handle four to seven hundred horsepower engines now out there.
Interestingly I first drove the $21K full boat a/c cabbed RTV, and thought the hydrostatic trans in it was super jerky and unpleasant to drive. The smaller gas powered model was actually fun to drive and scoots right along. Remarkable what 16hp can do.

Just understand that your UTV trans is nothing like the CVTs being discussed in this thread. Not going to debate the particulars of naming each variety. Just saying they aren't anywhere near the same. I have a Yamaha Rhino with a similar belt drive system as your Kubota uses. I consider it marginal. Minimal if discussing durability. No comparison to the VHT in my Kubota RTV 900. No comparison to the CVT systems being discussed here. So regardless of whatever name the manufacturers want to attach to a system, there is a LOT of variances. If Fendt can successfully utilize their system in 200HP tractors with success, I'm sold.

 

[Renze]

The Fendt Vario is the Pioneer example of a CVT, and it's the only clutch less version. All others like JD & CNH use clutch packs.

Renault patented it in 1908 but they were unable to produce it reliable and cost effective. Voith had the DiWa transmission for city buses, which was exactly a vario except the hydrostatic power branch was a hydrodynamic (torque converter) one.

Fendt uses clutch packs (or dog clutches) as well, it just can take off in high range while the others shift on the fly. Go rip some hard pan at low speed in high range with a Fendt and it won't last long... with the others, this misuse is made impossible.

 

[Renze]

Thanks for posting this. Hydrostatic power loss is pretty high and not getting into exact applications, its around 20%. Of course some transmissions are better or worst. Engineering Essentials: Hydrostatic Transmissions | Hydraulics content from Hydraulics & Pneumatics
Where as CVT's loss is in the 2-5% area. Pretty darn good

This is why Hydrostatic transmissions have not been successful is some applications. We won't consider one in a UTV.

Hydrostatic loss is 20% at peak efficiency: low speed high pressure (but not so much pressure that it will leak internally)
Roading a hydrostatic transmission with high speed and low pressure (high fluid motion loss) efficiency drops to 50% or lower. (source: Parker Hannifin specialist)
In a test of two, three years ago with CVT Magnums and 8R series and their powershift counterparts, the CVT models won on transport (high road speed is low hydrostatic speed, good efficiency) and the powershift models won on draft work. Or in other words, the CVT has no place on the grain plains.

Now a Vario, we all know what happens when we brake one rear wheel of a tractor : the differential makes the other wheel run at double the speed.

A vario is more or less your mechanical tractor differential, with the left wheel as transmission output shaft, the pinion as mechanical CVT input, and a hydrostatic motor connected to the right wheel as hydrostatic input. If we want to slow down, we need to speed up the other end of the planetary gear set, so in a power split CVT the efficiency is high at high output speeds, and low at slow output speeds, opposed to a conventional hydrostatic transmission (yet better overall)

Thats why land levelling contractors prefer a powershift or double clutch gearbox for their scraper tractors. A local contractor tried a Deere CVT and found it lacking just as much as their Fendt 900 series compared to the NH TG255 they had, so they got a brand new Deere 7250R Direct Drive for the land levelling and reclaiming work..

Aside of that, a Vario on average lasts 10.000 hours, like a hydrostatic, where mechanical gearboxes last longer and are cheaper to rebuild. (maybe not a Deere or CNH full powershift with 9 or 11 clutch packs, but a double clutch gearbox has only two.... Two to cause drag losses, two to replace at overhaul )

The double clutch gearbox is the new must-have in tractor land, the likely successor of partial and full powershift gearboxes with similar operating characteristics but the highest mechanical efficiency possible. Deere was the first, New Holland and Zetor intend to introduce theirs in 2017/18

After all, having an indefinate amount of gear ratios is a petty excuse for a poor lugging engine...

 

[daugen]

Just understand that your UTV trans is nothing like the CVTs being discussed in this thread.
absolutely. Thanks.

are the terms double clutch and dual clutch interchangeable?

Renze, great info.
LD1, isn't the issue what breaks "normally" and what does that repair cost? Vs. buying a brand new trans.
I agree with what you say about new costs,
though I wonder what those new ten speed automatics cost. A lot more than the last ten speed we bought...
Also, are these things getting so complicated that no one but the dealer can fix them and then all they can do is swap them out and ship them out?

I think for commercial operators cost tracking over 10k hours makes sense. For the rest of us, maybe compare service and repair costs over 5k hours instead.
If I have to fix a trans after thirty years, I don't think I'd get very upset. Unless the parts were built of Unobtanium
and were shipped in from the far reaches of the solar system. Wait until offshoring becomes off worlding...
Where out of this world quality and pricing are guaranteed.
There are those who think India might be the ninth planet out as far as parts availability confidence.
Yet Mahindra is the largest tractor company for a reason. They know their market.
And I bet CVT's aren't a big priority for them. Not yet anyway.

 

[Garandman]

Probably not much different than a manual or automatic transmission (if those were an option) in that vehicle.

Transmissions are expensive, especially if having a dealer do a total replacement. Dont matter weather its an auto, Manual, or CVT.

I had my Subaru WRX transmission rebuilt at Rallitech. $2,300 including a new center diff. Installation added hundreds but still less than 1/2 the CVT at a dealer.

 

[Weedy Fields]

Well I popped in hear to hear why CVT's are awesome.
I'm talking strictly cars now.
Haven't heard one thing that makes me think so yet.
Not being a wise guy or starting anything but I fell manuals are the best trans. out there and I'll state why.
Please inform me if a CVT can do these things.
Reasons why I'll always drive a manual.
1) better gas mileage, The last 2 cars I've owned with manuals have always gotten better mileage than same models equipped with autos. I've heard that CVT's are very good on gas, but I have not seen any real world comparisons. And please don't use EPA gas mileage numbers, they are not actual real world.
2) Easier on Brakes, again the brakes on my manual cars last alot longer than an auto equipped car, I would assume a CVT would be more like an auto trans and you use the brakes more. Please let me know on this any you CVT guys.
3) I can kick start a manual boxed car, can't do that on a auto, can you on CVT?
4) I can "rock" a manual box on extremely slippery conditions to get the car moving. Can't with a auto box, you drop it in drive, foot off the brake and the car is spinning already. Less control than a manual box. How about a CVT? More like an auto I assume, am I right?
5) Cost of maintenance/repair/replace. I easily get over 150K on manual cars before I ever need a clutch. Even when towing trailers. The only time I've blown up a manual box is thru severe abuse. Auto trans dying around 100k is not unusual especially when towing. I can buy a brand new manual box rated for 600ft of torque for $2500 dollars. How much for a auto or a cvt for the same torque rating?
6) Fun, nothing is enjoyable as driving any car equipped with a manual box. Economy cars especially are a world of difference in pep and fun when you match them up to a manual box.
How much fun is a CVT to drive, seems to me its like a auto, boring.

I don't follow all the latest technology so please educate me, let me know where I'm wrong.
Like to hear some real world info on CVT's in cars.

Thanks

 

[LD1]

Drivability, yes they are like an auto. So no you cannot rock them, or pull start them.

I don't think driving a manual is fun at all. Just one more tedious thing to have to do. Performance car....maybe, but my work car, trying to ship coffee or grab a bite to eat on the way in.....give me an auto anyway. Same for my truck, plowing snow with a stiff clutched stick.....I'll pass.

As to brakes....well my daily driver is indeed a manual. They didn't make a CVT in a 2001 Saturn, and the manual is way better than the autos for milage in those cars. But I don't engine brake /downshift at all while slowing. Brakes are cheap and easy to do. Synchros and clutch....not so much. So I'd rather add wear to the cheaper and easier to work on parts. And you can downshift an auto if you want too.

The wife's sentra /CVT has basically what is like 4 gears. There is drive and low, and either can have o/d on or off. So it will engine brake as well if you want, going down hills and stuff. And it has been flawless. Haven't had to touch a thing on that car (knock on wood) other than tires, brakes, and oil changes/filters. It's 8 years old with 150k.

As to milage, you would have to ha e two identical cars, same drivers, etc with the only difference being the trans. And in that case, I'd say that yes the CVT will do better than the std.

 

[KennyG]

Relative to the questions on CVTs:

They do get better gas mileage in the real world. Nissan went to CVT on their cars because they saw a 1 to 2 mpg increase over conventional automatics in the real world. In volume production, CVT is not more expensive than an automatic and is lighter in weight.

Not sure about the engine braking. I have two cars with CVTs but they are hybrids with regen braking so the brakes last a lifetime. Brakes last so long on cars these days I'm not sure this is an issue.

As far as reliability the CVTs are doing very well. My Escape Hybrid only has about 100K but they are commonly used in taxi service and many have run 300k to 500k miles and transmission failure has not been a problem. Most of the ones in cars are designed for light duty (focus on economy) and they are not rated for heavy towing. At some point we may see a heavier duty design, but there is probably a reason Ford is going to 10 speed F-150s instead of CVTs.

No, they are not as much fun to drive as standard transmissions, but now that trucks are automatic only, unless you are looking at sports cars, you don't have that option.

 

[crabjoe]

I don't care what tech is used for a transmission as long as it does it's job....

Now I do have a question... We've got a '15 Subaru Outback at home and the one thing that drive me nutz with the transmission is shifting into drive. There's a huge lag when putting the car in drive. I noticed this was true on all the Outbacks we test drove. Can anyone confirm if this is a Subaru thing or are all CVT transmissions like this?

Other than this lag, I have no problems with how the transmission performs... It does small little fake shifts, which I could care less about, but we get excellent MPGs for a fulltime AWD vehicle.