Hydro or Shuttle for the long haul?

[jenkinsph]

Happy birthday and enjoy your tractor with family.

 

[LS Tractor Owner]

Congratulations on the new tractor! And HAPPY BIRTHDAY! I think you are really going to like your choice!

 

[Beeenvenue]

Congrats. In the end most of the units out there now are really nice, just a matter of personal preferences on details.

As I age and knees begin to ache, etc I am very grateful for an HST. Better for others who occasionally use the machine as well. I’m sure your son could learn a modern shuttle but unless she’s a farm girl your wife will like the convenience of an HST.

 

[npalen]

Got a question on the derating of PTO horsepower on hydrostat models: I understand that the fluid transmission connection becomes more inefficient as more power is applied but is the PTO hydraulically driven? I would say on most CUT's that the PTO is mechanically driven, right? So in many applications such as tilling or bush hogging there is not a lot of power consumed to propel the tractor so does the PTO horsepower derate actually apply in those cases?
Help me understand, please.

 

[TMGT]

Got a question on the derating of PTO horsepower on hydrostat models: I understand that the fluid transmission connection becomes more inefficient as more power is applied but is the PTO hydraulically driven? I would say on most CUT's that the PTO is mechanically driven, right? So in many applications such as tilling or bush hogging there is not a lot of power consumed to propel the tractor so does the PTO horsepower derate actually apply in those cases?
Help me understand, please.

I believe the lower PTO HP is the result of parasitic loss from the HST pump. As far as I've seen, the pto hp is tested with the tractor static. I don't think I've ever seen a test comparison where the tractor is under power/loaded while testing the pto, at least in the compact sector.

This is something I've always been curious about testing to see what the actual difference between different transmission types while operating.

And yes, the pto is coupled to the engine mechanically, no fluid coupling.

 

[daugen]

My ancient Super A was a delight to drive, but very hard on my body, both in ergonomics and
wrestling with the manual steering. My 27hp hydro Massey/Iseki was like a small car to drive, super easy.
My 50hp all manual Massey built in India performed wonderfully and with power
steering it was far easier on me than the Farmall. But at the end of discing a multi-acre field, I could really feel it in my left leg.
Then in size on to a 57hp cab Kubota HST which was my favorite for doing everything well. Until I got my cab 70hp MF 4707 which
introduced me to the comforts of air suspension seats and the driving challenge of using an electronic powershift. I never did feel comfortable with
the powershift after spending years in the Kubota.

Most of us have driven a stick shift car or truck in our lives. I'd love to have a garage toy with a big V8, manual, and nice pipes. Manuals are fun
and for sure engage you in driving more. And I'm sure they are a tiny bit more efficient.
But there are times I'm driving the tractor I'd like to be less engaged, particularly when it comes to repetitive motions
like turning in headlands.

when I was using my powershift Massey with the man lift doing second story tree trimming with the lift up almost all the way, it was way more difficult to be smooth
with a clutch than it was with a treadle. If that smoothness comes at the price of efficiency, well ok by me. Just let me buy a tractor with 10-20hp more than I calculate
I need. Unless you are farming for a business, fuel costs aren't that big a deal to many of us. Capability and comfort are higher up in priority.

this was a helpful discussion. At one point I had four tractors and different types of transmissions. Switched back and forth from JD to Kubota hydro controls, which
we all know work very differently. Yes you learn how, but ultimately less effort is nice.
But if you want a larger frame utility tractor, which the OP doesn't, it's going to come with a clutch. Do IVT tractors come with a clutch? Feel like I should know...

pretty soon they will be electric anyway...

 

[npalen]

I believe the lower PTO HP is the result of parasitic loss from the HST pump. As far as I've seen, the pto hp is tested with the tractor static. I don't think I've ever seen a test comparison where the tractor is under power/loaded while testing the pto, at least in the compact sector.

This is something I've always been curious about testing to see what the actual difference between different transmission types while operating.

And yes, the pto is coupled to the engine mechanically, no fluid coupling.

So therein lies my question: How much parasitic loss is there when the tractor is running but stationary. How much horsepower does it take to drive the hydro pump when the swashplate is only maintaining minimal pilot pressure?
Would the hydrostat tractor, with the clutch disengaged, have the same rating as a gear drive? Seems like it would.........

 

[ptsg]

So therein lies my question: How much parasitic loss is there when the tractor is running but stationary. How much horsepower does it take to drive the hydro pump when the swashplate is only maintaining minimal pilot pressure?
Would the hydrostat tractor, with the clutch disengaged, have the same rating as a gear drive? Seems like it would.........

Well it wouldn't.

The HST tractors that have a clutch, the clutch is used to engage the PTO, so you can't press it without stopping the PTO.

The HST tractors that doesn't have a clutch, you can't press it either way, because there is none. It uses a clutch pack to engage the PTO.

And yes, I know that there may be some tractors with a clutch pack for the PTO and still have the dry clutch as well, but far less common.

 

[Blue Mule]

Using the Workmaster 25 that I'm likely buying as an example, the engine output is rated just a hair below 25 horsepower. But, the PTO is rated at 17 horsepower on the hydro model, and 19 on the gear model. So either way there is a substantial parasitic loss between the engine and PTO, but yes the hydro loses a little more.

It doesn't have a clutch pedal, so I'm assuming this means it's "independent PTO", which is still a little confusing to me vs. the "live PTO" but I'm not sure if one system has more parasitic loss than the other.

 

[npalen]

So what I'm wondering is how the two horsepower difference in the above example is "calculated". Is it based on an amount of drawbar pull in a given gear range, at a given ground speed, given RPM or is it just a SWAG.
For example, running a PTO driven chipper/shredder (at zero MPH hopefully) what happens to the two horsepower difference?