SRobertson

As I was looking for the end of the internet this evening I got on the topic of CVT's and kept searching.

Thought came to mind and I believe it has been brought up, if the technology for steal bets etc will reach the point that make CVT's an option for HD diesels such as our trucks or say a 1500?

Seems like if you could, you would be able to find tune all parameters of the engine to run at a very narrow band of power and maximize fuel consumption etc. With VGT turbos the boost could be adjusted depending on load while the RPM remained within a 500 rpm power band?

Not sure it is every realistic, but I would love to have something like that in a mini van or SUV and perhaps someday in a full size truck.

That said I do love the sound of a 12 or 24v going through the gears. The auto's just don't do it for me.

Curious of the thoughts out there.

SR

MikeyB

My daughter's car and my ATV has a CVT transmission. Not so bad with the ATV but I hate in the car. It wants to get into high range quickly as possible so it's easy to bog down the little four cylinder unless you add in more throttle input. Constantly modulating the throttle. Plus I really believe it hurts the fuel economy more so than the typical automatic transmission.

MikeyB

signature600

We have a very strong, very GOOD CVT in our Massey Ferguson tractors we sell.

Not sure how you could package it in a truck, but it would be different to say the least. Cost is probably the issue now, to make one hold any amount of power for towing.

Our replacement transmission for a 200-275hp tractor is in the neighborhood of $25,000.
Chris

SIXSLUG

I rode in a friends Nissan Murano and it seemed odd at first with no shift points, but it is definitely smooth. I couldn't quite get over being aware of it over a ten to fifteen mile trip at each stop sign.

It would have to be beneficial for heavy towing as the loading and unloading of a conventional trans would be greatly reduced, wear and tear on driveline parts would probably be less also.

Expense? I'm not sure what is inside them or how much is part of the price tag for a Murano, they are pretty expensive, his was over 40 grand if I'm not mistaken, but it definitely is on par with the euro and upper end japanese suv's.

How's economy? The acceleration is smooth and constant with no drop in rpm so it must be good.


If its worthwhile they will start optimizing a CVT for heavy apps.

SRobertson

My dad has a Nissan Maxima with the CVT and it is different, but is pretty quick and gets good gas mileage.

In the smaller vehicles the concept is proven and if we can just start getting some more small diesel options I think the market would match them up, if they haven't already in Europe.

Yikes!! on the price for tranny in your Massey Tractor. That would hurt! But I can image a Dodge Diesel CVT with manual shift mode that gave you 7-8 gears just for fun? You could always keep it in the sweet spot and fine tune the cam, injectors, turbo etc to give the best mileage.

Who knows... maybe, maybe not.

JD730

John Deere experimented with a steel belt CVT during the development of the New Generation tractors in the 1950's. IIRC I read that it was not suitable for the rigors of constant heavy work like tillage.

Before hydrostatic transmissions were widely used in combines they used a regular trans with a variable speed belt pulley setup to drive it, worked well as it didn't demand the kind of torque heavier work required.

I found this paper on CVT's very interesting.

http://elibrary.asabe.org/data/pdf/6...eries29rev.pdf

Busboy

My daughter has a 2011 Jeep Patriot that is "trail rated". It uses a CVT transmission that has a super low rock crawling gear. Not sure how it works but could be like a torque amplifier. Under normal diving 2 or 4 WD it's very smooth and they say it's capable of fording 19 inches of water.

cLAYH

PFFFT! If its got an IFS front end then its a Jeep in name only.

I heard GM was trying to develop a fully hydrostatic transmission for their diesel pickups. That would be pretty cool. Leave the engine at either its peak power or peak economy RPM and just stroke the tranny for required speed/torque.

Would need one MASSIVE tranny cooler!

NE frmhnd

The trouble with a hydrostatic transmission is that is highly inefficient. IHC had to re-name the 1066 hydro the hydro 100. It was about a 120-130 horse tractor, but the hydro ate up everything it had over 100. Guys were bringing them back to the dealers complaining they couldn't keep up with the neighbor's gear-driven 10.

Diesel Power had an article a couple years ago about a Cat CVT that could possibly see use in pick-ups. With a CVt you can keep the engine near it's peak torque output. So ideally for best fuel mileage with a CVT you would want the motor set up the same as for a stick or an auto- get the peak torque at the lowest RPM possible.

Sig600- that wouldn't be Marcie's in Pierpont, would it? I can't remember if they sell tractors or just short lines, haven't been there in 10 years. The only other MF dealer I can think of in the area is J E Andrews out of Espyville, not to be confused with Andrews Farm Equipment out of Conneautville. Which actually happens fairly often.

Busboy

They stopped making "Jeeps" a long time ago so I understand where you are coming from I had a 2006 Jeep TJ sport, the rag top was difficult to put on, there was no room for anyone in the back and if you did have the rear seat up there wasn't even room in the back for a small toolbox. The starter was a joke, it rode harsh because of the wheelbase and because they tried to smooth the ride out with coils it couldn't carry any hitch weight especially on the front. I don't expect the Patriot to carry a big hitch weight but I did expect the TJ to. I sold it after 1 year and kept the Landrover I hoped the Jeep would replace. Just comparing apples to apples. Meanwhile the sunroof and AC are nice in summer, the heated leather seats are toasty in the winter, there's room for 5 and even then there's lots of room for test equipment in the back. The Nav and 4X4 is enough to get it to the well/test site in comfort. Just saying. Oh and 22mpg on gas so better than our trucks.

sled4fun

CVT have been used for years on snowmobiles and do an excellent job at keeping the engine running in the sweet zone. The problem is that they are not going to be able to transmit all the torque and power needed for these trucks. I think the best way would be to have the cummins run in the sweet zone turning a generator. Then this power could be used to run an electric motor at each wheel getting rid of the trans, transfer case, front and rear differentials.

Mopar1973

ever consider the cost of one and the complexity of them if they fail? For instance take the Saturn Vue (don't ever buy one), we had one in our transmission shop with 70k on the odometer and the lady had just bought it. Paid $7000 for it and another $2500 for the bumper to bumper unlimited everything warranty for two extra years. Trans went and the insurance company handling the warranty valued the car at $2900. Warranty company was prepared to total the car out and is only liable to pay the amount that THEY value the vehicle at. Trans, at cost to the shop, was was $2950 not counting labor to install. You CANNOT get replacement parts to rebuilt the units because the parts aren't sold. Your only option is a used unit or a new replacement from GM, which is what she went with. She hadn't had it a month and almost $1100 out of her own pocket went towards the labor and so on and so forth of her low-mileage Saturn! The cost of repair (if possible) is staggering because of the lack of widespread application and the transmissions in the Saturn, according to Saturn themselves, are good from 30-50k miles IF you're lucky.

DWeiler

Wife's 2008 Nissan Sentra is prone to some failures in that year of CVT----i hear its the oil pump,but what does Nissan do---they stand behind there mistakes and extended the warranty for 10years---200,000KM(125000 miles),Also if you paid out of the original warranty repair for a rebuild before this extended warranty(after 100,000KM) they refunded your money if you had a receipt from any tranny shop .The Mrs only drives about 15,000 a year so we don't have to worry about it for another 6 years---only condition is that the dealer has to service the unit every 60,000KM.So far no problems and the it runs fine---"Zippy" little car for her.(38MPG highway).DW