Hydro or Shuttle for the long haul?

[metalbender]

Anybody have a line where sub compacts and compacts divide? When I bought my Massey 1742 cab model, I saw some of the subs. Just didn't look like a tractor. Dealer said thay get them used when people buy too small in the first place. Like the two pedals for the hydro, treddle didn't do it for me either.

 

[paulfun9]

That is why you buy enough HP to overcome the power lost with a HST vs a gear tractor.
So, buy a 30HP gear or a 35HP HST, you will have the same amount of power to the wheels or the PTO.
There was someone on here who is looking at going from a 25HP to a 40HP in the same frame size because the 25HP doesn't have enough power to go up a steep hill in high.

Aaron Z

You will need more than 5 hp to cover the difference, and in most cases by the time you go big enough to cover the hp needs the frame size changes and your back to feeling the losses with more overal wieght.

 

[jenkinsph]

You will need more than 5 hp to cover the difference, and in most cases by the time you go big enough to cover the hp needs the frame size changes and your back to feeling the losses with more overal wieght.

I don't think there is more than 5 hp. loss. And in most cases you can go for the higher hp model in a product line to cover the losses.
while it may cost a small amount more to run hydro vs. gear a person really should tryout both for awhile at the dealership. Then buy the one they like the best.

 

[paulfun9]

I don't think there is more than 5 hp. loss. And in most cases you can go for the higher hp model in a product line to cover the losses.
while it may cost a small amount more to run hydro vs. gear a person really should tryout both for awhile at the dealership. Then buy the one they like the best.

Have you ever experimented with them side by side?
Why is my 20hp gear faster uphill than my 50 hp Hst?
Why is my 40 hp HST just as fast up the hill as my friends 45 hp unit?
And why is his no faster than his neighbors 50 hp Hst unit?
Your words “I don’t think there is” say lots more than you think.
I may be accused of doing non scientific studies, but most here are just thinking with no study, test or comparrison at all.

 

[pmsmechanic]

Have you ever experimented with them side by side?
Why is my 20hp gear faster uphill than my 50 hp Hst?

It could be partially because of the weight difference between the two tractors. And which one would you pick for fussy front end loader work?

Why is my 40 hp HST just as fast up the hill as my friends 45 hp unit?
And why is his no faster than his neighbors 50 hp Hst unit?

Interesting comparisons. Are the tractors all the same brand?

Your words 的 don稚 think there is say lots more than you think.
I may be accused of doing non scientific studies, but most here are just thinking with no study, test or comparrison at all.

The thought has run through my mind that because of the swish plate and how it works I wonder if HST is more efficient at slower speeds than higher ones. At slow speed your only pushing a small amount of oil through the oil passages compared to higher speeds. Does HST cost more efficiency at higher speeds vs slower ones?

Just some thoughts on what your observations.

 

[the old grind]

With HST our engine is never driving the wheels. The HST motor does that and thereby limits what torque the wheels get. The hp 'loss' is what's drawn by the additional pump for HST.

HST pedal controls the motor's swash plate angle. Speed is, as always, a matter of HST motor and range selection. Tractor races would prove ___ if not same frame, HST motor and o'all weight.

Physics and mechanics rear their ugly heads.

 

[aczlan]

You will need more than 5 hp to cover the difference, and in most cases by the time you go big enough to cover the hp needs the frame size changes and your back to feeling the losses with more overal wieght.

Kubota lists for the L3940
Net HP: 38.5 hp
Gear PTO:33 hp
Hydro PTO:31.5 hp

So 1.5HP more in parasitic losses for a HST transmission vs a Gear transmission (probably running the HST and the hydraulic pump vs just the hydraulic pump).

HST will have more loss of efficiency in delivering power to the ground (hydraulics are generally around 80% efficient), so 31.5HP in at 80% should give you 25.2HP out (Kubota's HST drive may be little more efficient, but 80% is the general rule of thumb).

Gear is around 90% efficient (91.4% in a Nebraska test for a 12 speed gear Kubota M5700DT), 33HP in at 91.4% efficency will give you 30.18HP to the ground.

So, almost exactly 5HP to the ground difference between gear and HST on the same tractor with the same engine.

Aaron Z

 

[paulfun9]

Just some thoughts on what your observations.

That green print sure is hard to read.

Which would I pick? 99% of the time I take a gear or power shift unit over my 3 HST tractors. The HST is here for the wife’s convenience. I have no issues or concerns running a gear but tend to gravitate to the power shuttle.

We are talking DK 40 to DK 45 to DK 50 all open station with the difference between observations being the driver and hill at my friends is steeper.

I think your thoughts on the swash plate or should we say inability for the HST to be efficient at higher speeds might be more in line with the real problem. Have read test after test with similar results as in your comparrison but out in the real world I see and feel more of a difference.

By the way similar results have been witnessed with other brands of tractors but they were not all the same brand. So I don’t put much stock into the efficiency of one brand being better than the rest being a factor. But there we go again with the thinking thing, it will get us all in trouble!

 

[the old grind]

what Aaron says makes sense to me.

That said, what it means to me is that I'll surely have to be in low range to spin all four and continue to done so with far less than rated hp to the wheels.

(got box blade, grapple, tooth bar, disc?)

btw, loaded tires or not & BB with 4 cement blocks and up to 1/2 bucket sand/gravel for front ballast I can run out of traction before I run out of torque to the wheels. Two await new fronts already on hand. I had 2 WD 45 hp Deeres that struggled to pill my disc smoothly even with draft control. (use wrist/fingers vs arm to trim)

 

[pmsmechanic]

That green print sure is hard to read.

I noticed that too but since this was the first time I had attempted anything like that I just figured I would leave it. I'll pick a different color next time. It would be nicer if it was closer to a John Deere green.