Gear or Hydrostatic Transmissions for Compact Utility Tractors?

[Sawyer Rob]

I never trade down, I just add another tractor! lol

I have to add, I had to smile today every time I used my brakes to turn, as I was rotavating with a gear drive tractor, thinking about this thread... lol

SR

 

[MossRoad]

I never trade down, I just add another tractor! lol
....

Wish that were the case for us, but I only have so much money, time, space, etc.... and, really no need for more than one machine. With our quick attach, its a 15 second job to switch implements without getting off the tractor (add 30 seconds and quick hop-on, hop-off to hook up hydraulics if its a powered implement). With the old IH and a 3pt, it was a chore. I hate 3pt hitches and hope to never have to use one ever again. :thumbsup:

 

[gladehound]

If the tractor is rated at XX PTO HP, its XX PTO HP. The same thing applies to draw bar HP regardless of how it gets there.

I thought that PTO hp is hp measured at the PTO? Is this not correct? If this is correct, than it follows that PTO HP on any tractor can only be at the rated HP when the tractor is not under another load at the same time.

For example, if you are running hydraulics you are using some of the engines hp, therefore usable PTO HP goes down. Likewise if you are pulling something by the draw bar usable PTO hp goes down. This happens regardless of the transmission.

All transmissions convert power to heat. The harder you work the transmission to put power to the ground, the more power that is converted to heat. Power that is put to the ground plus power turned to heat are not available for the PTO. Therefore, if one transmission is less efficient than another at putting power to the ground, there is a correspondingly greater reduction in available PTO hp while power is being put to the ground.

It would be interesting to see what the draw bar HP is for the same model with gear vs HST. My guess is that you would get more drop off in draw bar hp than in PTO hp. And that is the point that I was trying to make. Unfortunately, draw bar hp isn't typically listed for small tractors.

 

[gladehound]

I found this and it proves my point. Notice the huge difference in draw bar hp and comparatively small difference in PTO hp between HST and gear.

"the IH 1066 was offered as a gear drive tractor developing a maximum 100.5 drawbar HP. The hydro version produced 84.88hp. The relative PTO HP were 116 and 113, respectively. All other factors are equal or very close between the two versions of this '70s farm tractor. Info from Nebraske tests # 1081 and 1083, 1971. "

 

[4570Man]

I would hope a HST transmission is more efficient than it was in 1970. Besides I don't really care what the draw bar HP is. I do very minimal draw bar/3 point hitch work.

 

[4570Man]

What tires are the best? What brand is the best?

 

[gladehound]

I have to thank the HST fans here for pushed me to think about this more deeply than I have before. The result is that I am more solidly entrenched in the gear camp than ever before.

Pros for gear....

-generally a slight PTO hp advantage with same engine (no big deal)
-substantial draw bar hp advantage with same engine (big deal)
-same money buys much bigger tractor which increases both advantages above. Pulling / pushing power with gear ~1.5X that with HST at similar price. (Huge deal)

Pros of HST...

-more convenient to operate, thus better for new operators. (not a big deal for me, but obviously a big deal for many)
-really the only choice if you need frequent infinite speed variation near zero mph without damaging equipment. (huge deal for anyone using their machine this way)

Verdict
- Get gear if you need brute force or sustained high draw bar hp for your dollar. Add a power reverser if frequent direction changes also needed. The clear choice for getting a high volume of work done on a minimal budget.
- Get HST if you value convenience and ease of operation, have physical limitations that makes gear a challenge, have frequent need for infinite speed adjustment approaching zero mph or frequent low speed direction changes, and do not need sustained high draw bar hp. The clear choice for frequent fine low speed changes in speed / direction.

 

[MossRoad]

I found this and it proves my point. Notice the huge difference in draw bar hp and comparatively small difference in PTO hp between HST and gear.

"the IH 1066 was offered as a gear drive tractor developing a maximum 100.5 drawbar HP. The hydro version produced 84.88hp. The relative PTO HP were 116 and 113, respectively. All other factors are equal or very close between the two versions of this '70s farm tractor. Info from Nebraske tests # 1081 and 1083, 1971. "

Good find. :thumbsup:

 

[MossRoad]

I found this and it proves my point. Notice the huge difference in draw bar hp and comparatively small difference in PTO hp between HST and gear.

"the IH 1066 was offered as a gear drive tractor developing a maximum 100.5 drawbar HP. The hydro version produced 84.88hp. The relative PTO HP were 116 and 113, respectively. All other factors are equal or very close between the two versions of this '70s farm tractor. Info from Nebraske tests # 1081 and 1083, 1971. "

Now throw this into the old blender....
TractorData.com International Harvester 2500B industrial tractor engine information

This is the specs for our old IH2500b.
Ours had the C200 gas engine. It was available with a C239 diesel engine as well.
Several transmission choices.
Check out the engine HP for both diesel and gas engines...
Both the diesel and gas engines are rated at significantly higher HP with the HYDRO transmission.... what???
Maybe to compensate to get the same PTO and drawbar HP out of both transmission types? Or maybe this page isn't complete...
Anyhow, also note that the diesel is 39 cubic inches larger than the gas, or about 20% larger displacement to get similar numbers.

And here's a report on the IH574. Its the AG version of this tractor.
TractorData.com International Harvester 574 tractor tests information
Both of these tests were done with gas and diesel engines, and both with the same gear transmission.
The diesel produces more power, but uses about 25% less fuel doing it. So the larger displacement engine uses significantly less fuel to produce similar power.
... But that's a discussion for another thread: GAS VS DIESEL! :laughing:

 

[gladehound]

:thumbsup:

Now throw this into the old blender....
TractorData.com International Harvester 2500B industrial tractor engine information

This is the specs for our old IH2500b.
Ours had the C200 gas engine. It was available with a C239 diesel engine as well.
Several transmission choices.
Check out the engine HP for both diesel and gas engines...
Both the diesel and gas engines are rated at significantly higher HP with the HYDRO transmission.... what???
Maybe to compensate to get the same PTO and drawbar HP out of both transmission types? Or maybe this page isn't complete...
Anyhow, also note that the diesel is 39 cubic inches larger than the gas, or about 20% larger displacement to get similar numbers.

And here's a report on the IH574. Its the AG version of this tractor.
TractorData.com International Harvester 574 tractor tests information
Both of these tests were done with gas and diesel engines, and both with the same gear transmission.
The diesel produces more power, but uses about 25% less fuel doing it. So the larger displacement engine uses significantly less fuel to produce similar power.
... But that's a discussion for another thread: GAS VS DIESEL! :laughing:

Good stuff Moss! I think you're right that they are trying to keep pushing / pulling ability about the same with different transmissions by bumping up engine HP.

The gas vs diesel discussion would be entertaining! :thumbsup: