A hydro since the late sixties early seventies has been used to enhance the speeds of PTO work or to work at finite speeds to enhance the speed of crop processing. They can handle this type work better then and faster then a gear drive even with the parasitic horsepower drain of this style of transmissions. Today we are working with the CVT types that are a type of snowmobile drive system but by far more advanced but they still haven't shown us what they will do in the long run. Farmers have told us they are not as good on fuel as the gear drives but they do like the variables.
When the hydro first was offered to the farmers many were sold with out proper training as well as using them with the "they do it all" slogan. Such a shame!
As many of you know they do loose some on a hard pull from within. A good gear drive being the most economical on long hard pulls and then you have some of the many types of power shifts that will burn less then the hydro but more then the gear drive. The hydro has been a vary versatile transmission and had many duties though the years.
The maintence is normally higher on a hydro then a gear drive but the wear factor comes in! Ag customer a dairy farmer, two sixty five horsepower tractors that they had owned and both tractors were in the 5,000 to 6,000 hour range. The complaint was nobody liked to drag with the hydro or do heavy work. We talked for a bit and the hydro was put on the cattle trailer running between the three dairy barns about a six mile run. The hydro also was used for PTO work tedder and rake at first and then pulling the 12 hydro swing mower instead of the 100 PTO hp gear drive.
They were amazed over it's efficency! When talking after a year it was brought out that they had put three sets of tires and one clutch job in the gear drive vs the worn out originals on the hydro.
We often see ten thousand plus hours on the hydro's with no troubles and have a few that are double that. They will often go more then an engine.
Good info dfkrug. Thanks for the post. On the larger equipment like a dozer do they use a swash plate type transmission? If not what design is it? Just curious. How come you had your HST apart.
I don't mean to make this thread go on a tangent, but it occurs to me that concrete trucks are mostly powered by hydraulic motors. That means a motor must also have a pump powered by an engine PTO. I'm not sure how the speed of the motor is controlled, but fluid power seems to be pretty darn reliable in this application. By the looks of some of these trucks, they have been around for a long time with thousands of hours while mixing up to 9 yards of concrete at a time. I only hope my HST would be as reliable.
The only portion of a Concrete (good job on the correct term, they are not "cement" trucks!) truck...
Hear, hear! Calling your driveway a "cement" driveway is like saying your
house is made out of nails.
Most TBN members may not be aware but older Fergie tractors used a
gear transmission coupled to an automotive style torque converter. It
works pretty well as you can shift at idle speed with no clutch, and even
the hyd pump only ran above idle speed. I drove an old MF30 or 35 with
FEL. I wonder why you don't see that approach anymore?
Another note: CVT is coming to CUTs in the new New Holland units. They
would have the efficiency of gear trannies, the ease of speed changes
like HSTs, but not the safety of HSTs.
The "vast unwashed masses" won't know if that is Constant Velocity or Continuously Variable, but it won't matter
What you describe ..easier work like haymaking or pulling a trailer is where i would expect them to fit in but it was grain or potato farms with endless hours of heavy pulling ploughs and cultivators that seemed to give them the bad name...I am talking 80hp+ and these were 1980's machines...