How much power do you lose with hydro over gear in a 30 to 35 HP tractor? I have heard from a Kioti dealer that I may prefer a gear as it provides much more power than a hydro in the same motor. Is this really true?
Loss of power with hydro over gear???
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DUMBDOG
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Looking at the specs for NH and Kubota, you loose about five per cent of the HP to the pto from the engine. Drawbar horsepower is about 85% of the pto HP. This works out to about 1.5 HP loss to the pto and 1.7 to 2.0 HP on the drawbar, not a huge difference.
timb
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The drawbar loss % will be higher than the PTO loss % on a hydro compared to a gear, due to the basic nature of a fluid transfer transmission throughput efficiency versus a gear.
I've never seen CUT drawbar numbers measured or listed anywhere, but a rough guesstimate on a 32 hp tractor would go something like this:
Engine (gross) hp = 32 (both tractors)
PTO hp = 27 hp (gear), 25 hp (hydro)
Drawbar hp (guesstimate) = 23 hp (gear - 85% efficient), 19-20 hp (hydro - 70%-75% efficient).
First - the difference from the gross engine hp to the PTO number is due to all the parasitic losses of the various system components, pumps etc.,. The hydro has a little more loss here due to the hydro tranny pump thats not on the gear tractor. But - note that the PTO numbers are measured with the tractor stationary, I'm not sure if the loss would increase or not as the tractor is moving and that pump has to do work.
Second - a rough estimate for a gear tranny efficiency (hp in divided by hp out) is around 85%. So for this example, that 32hp CUT might put out around 23 hp at the drawbar.
A hydro transfer is supposed to be about 70 to 75% efficient. So in this example, probably around 19-20 hp at the drawbar.
Not a giagantic difference, but there will be a difference.
Caveat #1: The above example was based on general 'rules of thumb' applied against a popular CUT model, not hard facts.
- But in this case, as is typical on CUT lineups, there is a more powerful engine version of the otherwise same tractor model that starts with a 35 engine hp. Crank the numbers and that gets you back to about the same drawbar hp as the 32 hp gear tractor.
So for a really rough rule-of-thumb, for approximately equal power output, go up one engine size for a hydro versus a gear. That does make going hydro a little more expensive than just the obvious cost of the hydro option on the same tractor. Not good, not bad, just is what it is.
Caveat #2: The difference in drawbar hp will be even less meaningful if the tractors are not ballasted to their full potential. Since many CUT owners like to keep their tractors reasonably light to keep from destroying their yards, the tractors are traction, not hp, limited. Unless you ballast your tractor heavily, the hydro 'loss' will probably not really mean all that much in the real world.
I've never seen CUT drawbar numbers measured or listed anywhere, but a rough guesstimate on a 32 hp tractor would go something like this:
Engine (gross) hp = 32 (both tractors)
PTO hp = 27 hp (gear), 25 hp (hydro)
Drawbar hp (guesstimate) = 23 hp (gear - 85% efficient), 19-20 hp (hydro - 70%-75% efficient).
First - the difference from the gross engine hp to the PTO number is due to all the parasitic losses of the various system components, pumps etc.,. The hydro has a little more loss here due to the hydro tranny pump thats not on the gear tractor. But - note that the PTO numbers are measured with the tractor stationary, I'm not sure if the loss would increase or not as the tractor is moving and that pump has to do work.
Second - a rough estimate for a gear tranny efficiency (hp in divided by hp out) is around 85%. So for this example, that 32hp CUT might put out around 23 hp at the drawbar.
A hydro transfer is supposed to be about 70 to 75% efficient. So in this example, probably around 19-20 hp at the drawbar.
Not a giagantic difference, but there will be a difference.
Caveat #1: The above example was based on general 'rules of thumb' applied against a popular CUT model, not hard facts.
- But in this case, as is typical on CUT lineups, there is a more powerful engine version of the otherwise same tractor model that starts with a 35 engine hp. Crank the numbers and that gets you back to about the same drawbar hp as the 32 hp gear tractor.
So for a really rough rule-of-thumb, for approximately equal power output, go up one engine size for a hydro versus a gear. That does make going hydro a little more expensive than just the obvious cost of the hydro option on the same tractor. Not good, not bad, just is what it is.
Caveat #2: The difference in drawbar hp will be even less meaningful if the tractors are not ballasted to their full potential. Since many CUT owners like to keep their tractors reasonably light to keep from destroying their yards, the tractors are traction, not hp, limited. Unless you ballast your tractor heavily, the hydro 'loss' will probably not really mean all that much in the real world.
Beats me -- what I don't know won't hurt me. I wanted hydro for the ease of use and convenience, and the power I've got is the power I've got. If I was worried about power I would have bought a hydro tractor with more power, not a gear tractor. Sounds like the dealer has some gear tractors he's having trouble getting rid of...
LBrown59
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</font><font color="blue" class="small">( How much power do you lose with hydro over gear in a 30 to 35 HP tractor? I have heard from a Kioti dealer that I may prefer a gear as it provides much more power than a hydro in the same motor. Is this really true? )</font>
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I don't see where it matters how much power may be lost as long as you have plenty of power left to get the job done.
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I don't see where it matters how much power may be lost as long as you have plenty of power left to get the job done.
JerryG
Super Member
Tim,
Thanks for the write up. I think that is best layed out write up on the hp difference that we have had on TBN. But, know matter what the facts are, there will be many that will still try to say that it doesn't make a difference, because that think that theirs is the best. Most of the time, for the posters here it really doesn't make any difference because they don't ever use all their hp anyway. And since they don't need all the hp it is not a problem and they don't need to go up in size.
Thanks for the write up. I think that is best layed out write up on the hp difference that we have had on TBN. But, know matter what the facts are, there will be many that will still try to say that it doesn't make a difference, because that think that theirs is the best. Most of the time, for the posters here it really doesn't make any difference because they don't ever use all their hp anyway. And since they don't need all the hp it is not a problem and they don't need to go up in size.
MossRoad
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Very nice write up, Tim. /forums/images/graemlins/smile.gif
Bob_Skurka
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widmn . . . yes there is a loss but it might not really matter to you depending on what you are attempting to do with the tractor. Kioti has 3 tractors that are in the 30 to 35 hp ranges. LK, CK both come in 30hp and DK is available in 35hp. All 3 are different machines with different characteristics and that alone begs the question what do you need to do?
The tasks should dictate not only your choice of tractor but your choice of transmission.
The tasks should dictate not only your choice of tractor but your choice of transmission.
Evasive1
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</font><font color="blue" class="small">( So for a really rough rule-of-thumb, for approximately equal power output, go up one engine size for a hydro versus a gear. That does make going hydro a little more expensive than just the obvious cost of the hydro option on the same tractor. Not good, not bad, just is what it is.
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The best short explanation so far.
I agree with the others Tim, great job.
Like Bob stated, you first need to know what task you want to do with your tractor and then go from there.
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The best short explanation so far.
I agree with the others Tim, great job.
Like Bob stated, you first need to know what task you want to do with your tractor and then go from there.
