Confused: CVT vs. Hydro??

   #1  

MiserableOldFart

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I have been trying to find out what the advantages of a CVT over a Hydro are, and just don't understand, probably because I'm old and thick in the head. Now, if it weren't for loader work, I would certainly have a manual shifting tractor of some kind, but the loader makes the hydro a nice convenience.. what makes the CVT preferable? Can anyone 'splain this?

Thanks!
 
   #2  

KennyG

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The CVT advantage is efficiency. It is usually fully mechanical (steel belt on conical pulleys) so there are almost no losses in the transmission. The hydro transmission has a pump that sends fluid to a hydraulic motor, both of which have significant energy losses.

The disadvantage is that you have to have a reversing gearbox to change directions, and shifting that is like a manual transmission, less convenient than a hydro.

Interesting point - my hybrid car, like most has a CVT transmission. It doesn't have a reverse gear. You can only back up with the electric motor.
 
   #3  

jdbnh

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well a cvt gives you a lot of options for one. where a hydro is jsut two peddles forwards and backward with your speed ranges. The CVT doesnt have the high pitched "whinny" sound liek a hydro does either. THE CVT is not jerky like a hydro, it is very smooth. you have many different settings on a CVT, down to how you want the foot pedal to react when you step on it. it gives your tractor and the operator a lot of choice depending on the job at hand. Higher horse power tractors have them and in applications like plowing, loader work, planting, baling, you can really set the speed, rpms, etc how you want them for the most efficient work. if you would let me know what your email is i can send you a more in detail explanation
 
   #4  

jdbnh

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The CVT advantage is efficiency. It is usually fully mechanical (steel belt on conical pulleys) so there are almost no losses in the transmission. The hydro transmission has a pump that sends fluid to a hydraulic motor, both of which have significant energy losses.

The disadvantage is that you have to have a reversing gearbox to change directions, and shifting that is like a manual transmission, less convenient than a hydro.

Interesting point - my hybrid car, like most has a CVT transmission. It doesn't have a reverse gear. You can only back up with the electric motor.

actually in NH CVT on the compact tractors, they have a shuttle shift to go along with the CVT and it just has forward adn reverse cltuches. no other gearboxes or anything. it is pretty simple. i can send you info to read if you like. just let me know your email
 
   #5  

farmall40

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The only downfall that I have found with the CVT is it takes about 2 seconds to change direction. Trust me it's no big deal. I owned 2 hydro units before the CVT, these things should't even be mentioned in the same sentence. The power and the smoothness of the CVT is incredible. Let's just say I won't be going back to a hrdro anytime soon.
 
  
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MiserableOldFart

MiserableOldFart

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Thanks for the info, all. JDBNH, my email is "[email protected]" Does anyone have any thoughts as to which are more rugged and less trouble prone? I had leaned toward a manual shift until I read about loader work being easier with that hydro pedal, but I've always felt the manual tranny had less to go wrong long term than the hydro. Some dealers seemed to agree, others not. I certainly appreciate the hydro when I'm using the loader to move snow around.
 
   #7  

jdbnh

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what i am about to send you will probably answer that question on durabilty.
 
  
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MiserableOldFart

MiserableOldFart

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Thanks for the info, jdbnh. Wow, tractors have certainly become high tech items! Wish they were simple like computers ;-)
 
   #9  

jdbnh

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Thanks for the info, jdbnh. Wow, tractors have certainly become high tech items! Wish they were simple like computers ;-)

i certainly agree with you on that. nothing is simple anymore. Anytime you have a questions jsut holler
 

skspurling

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what i am about to send you will probably answer that question on durabilty.

Well, that's all fine and dandy for old fart, but the rest of us may want to know about the durability of the CVT. ;)

I would imagine, because of the mechanical nature of the system, you would be more prone to stresses and wear than with an HST. Is that wrong? And how would that not be the case? If you properly maintain an HST, any abrasives in the working fluid should be filtered or flushed before they cause much wear, and the compressibility of the working fluid (which makes it less efficient than a mechanical system) should reduce the actual shock on the mechanical parts.
Some people may think of an HST like a big pump, some hoses, and a couple of hydraulic motors driving the wheels, but that is no where near what it is. It would be more like a torque converter with extra valving. It's not that inefficient. Not saying that a CVT isn't nice, but I don't think you get all benefit and no down side. Any one telling you that is a sales person. I would not be surprised if the overall lifetime of the components in a CVT were not shorter than a standard gear based transmission. They just don't know that yet because they have not been on the market long enough.
 
 
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