Hydro vs Gear Question

Would a loader tractor with a hydro transmission be ok for field work such as disking?
Something in the 40-50 hp. range pulling 10-12 foot disk?

(quoted from post at 10:16:42 02/15/18) Would a loader tractor with a hydro transmission be ok for field work such as disking?
Something in the 40-50 hp. range pulling 10-12 foot disk?

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Depends on what your expectations are .

I am struggling in trying to answer your question. I don't know what model disk you have, your expectations on how deep into the soil you intend to operate this disk, or your soil conditions/types, the tractor you are considering and if the horsepower rating is based on PTO horsepower output or on the engine horsepower output. I found a publication from the University of Georgia which gets much more in depth on this. Here is the link: http://caes2.caes.uga.edu/engineering/pubs/documents/farm%20tractor.pdf

It is stated in that publication, the engine in a tractor will transfer 75 to 85 percent of its power to the PTO. Converting the engine horsepower to drawbar horsepower will even further reduce this number. In just doing a quick look at some historic Nebraska Tractor Tests, will confirm how less efficient a hydrostatic drive is at generating drawbar horsepower. I have a tractor (with hydrostatic drive) rated approximately 70 pto horsepower. According to the Nebraska Tractor Tests, the maximum drawbar horsepower generated is 52 hp, which equates to 73 percent drawbar hp to pto hp rating efficiency. That same tractor in a gear drive is rated at 66 pto hp and 57 maximum drawbar hp, which equates to 86 percent drawbar hp to pto hp efficiency. In a nutshell, hydrostatic drives are significantly less efficient in converting engine horsepower to drawbar horsepower. I suspect this will tend to hold pretty true for all hydrostatic ground drives.

So, consider your 50 hp model. If that is engine horsepower rating, you are down to only about 29 drawbar horsepower. If that 50 hp rating is pto rated, you are going to be down to about 36 drawbar horsepower.

As I have found, I can pull a 12 foot disk with my A John Deere (29 hp with distillate pistons), but I am only going to be "scratching" and I am only going about 4 mph. I am not going to accomplish much in terms of moving and mixing soil with this tractor pulling this disk. If I wish to do a fair amount of mixing with good depth of operation, I am going to need more horsepower. Factor in the soil conditions, as mentioned in the University of Georgia publication, will affect the power needed to perform your tillage task. I would much rather have an excess of power for the task, and be able to travel a bit faster in normal or good conditions, and still be able to do a decent job in difficult conditions.

I would not want to run it too long or too hard for fear of burning up the hydro !
Maybe check into something with a power reverser (deere) or glide shift (Kubota)they might give the best both have to offer ?

Neighbor had two IH 656 tractors. One was a gear drive and the other a hydro. He pulled 4x14 plows with the gear drive but had 3x14 on the hydro. The hydro took that much more power for the hydrostatic drive.

It sounds like your talking about a modern compact utility tractor that would be rated 40-50 HP. One big thing to keep in mind when most of us old tractor guys talk about horsepower we are talking about PTO horse power not gross HP. The majority of the tractors today have the GROSS horse power advertised. So that 50 GROSS HP tractor could easily only be a 35 PTO HP tractor.

Doing tillage work with a hydro tractor will make them get really warm real fast.

The McCormick is 47 HP, I think my 30 HP Farmall H would out pull it easy.

its easier to outrun the dust when you go faster.