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.
)</font>
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.
)</font>
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.
He had both the CK30 HST, CK30 and the DK35. I told him I was in a very hilly area. He said I might be better off with a gear tractor as it has more power on the ground for the price. He also recommended R1 tires for maximum grip as the R4s tend to slip sideways on hills.
DocHeb
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I'd like to hear others' opinions on advantages of HST vs. Gear for hilly areas. I know with my HST I can vary power/torque to the wheels to meet the needs of hill climbing, but I have no gear experience to compare it with. Do you have to stop to change gears to get extra torque to go up hills, then stop to change gears to get the extra speed on flatter areas?
JerryG
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I rarely stop to change gears or completely stop to change directions with my power-shuttle. More torque or more speed is what more gears are about, isn't that standard knowledge?
DocHeb
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</font><font color="blue" class="small">( I rarely stop to change gears or completely stop to change directions with my power-shuttle. More torque or more speed is what more gears are about, isn't that standard knowledge?)</font>
I do understand the inverse relationship of gearing for speed vs. torque, so I guess I do have that "standard knowledge". As I stated in my post, however, I am ignorant as to how applicable this is to everyday use as I have no experience. Because of my ignorance in this matter, I was very careful to not tout HST as better for hills than gear, but rather asked for informed opinions from somebody that has experience.
Thank you for the first part of your reply.
I do understand the inverse relationship of gearing for speed vs. torque, so I guess I do have that "standard knowledge". As I stated in my post, however, I am ignorant as to how applicable this is to everyday use as I have no experience. Because of my ignorance in this matter, I was very careful to not tout HST as better for hills than gear, but rather asked for informed opinions from somebody that has experience.
Thank you for the first part of your reply.
btolle
Platinum Member
</font><font color="blue" class="small">( I'd like to hear others' opinions on advantages of HST vs. Gear for hilly areas. I know with my HST I can vary power/torque to the wheels to meet the needs of hill climbing, but I have no gear experience to compare it with. Do you have to stop to change gears to get extra torque to go up hills, then stop to change gears to get the extra speed on flatter areas? )</font>
Depends on the hill. I assume mean a hill steep enough to bog the engine down in a higher gear the the answer is yes, you would need to downshift. But if I am in Hi range with my HST I may have to shift to Lo range to get up that same hill.
As for gear vs. hydro I like my hydro but it is like air conditioning in a car, it will cost me power and fuel mileage. When I am hot I don't give a darn about horsepower and mileage, I just want to get cool. In other words, whatever HST costs me it is worth it to me. May not be to some, but that is a matter of personal choice and circumstances.
"There is no free lunch (or horsepower)."
Bill Tolle
Depends on the hill. I assume mean a hill steep enough to bog the engine down in a higher gear the the answer is yes, you would need to downshift. But if I am in Hi range with my HST I may have to shift to Lo range to get up that same hill.
As for gear vs. hydro I like my hydro but it is like air conditioning in a car, it will cost me power and fuel mileage. When I am hot I don't give a darn about horsepower and mileage, I just want to get cool. In other words, whatever HST costs me it is worth it to me. May not be to some, but that is a matter of personal choice and circumstances.
"There is no free lunch (or horsepower)."
Bill Tolle
JerryG
Super Member
The reason that I said it that way was because I knew that your hydro had a range selector. Other than that I guess I don't get what you are wanting. Unless it is to say that yes you do go to a higher gear to go faster and go to a lower gear to have more torque. /forums/images/graemlins/confused.gif
Bob_Skurka
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<font color="red">
I'd like to hear others' opinions on advantages of HST vs. Gear for hilly areas. </font>
I have a couple steep drops and I've used both gear and HST machines on my property. On the slopes I would never, let me repeat that NEVER, go back to working on a slope with a gear tractor after using HST on a slope. The only thing you have to do be be in the correct range (in my case LOW on my 2 range N.H. and LOW on my 3 range Kubota) but after that there is nothing to worry about. I could not even imagine doing any loader work on my slopes with a gear machine.
I'd like to hear others' opinions on advantages of HST vs. Gear for hilly areas. </font>
I have a couple steep drops and I've used both gear and HST machines on my property. On the slopes I would never, let me repeat that NEVER, go back to working on a slope with a gear tractor after using HST on a slope. The only thing you have to do be be in the correct range (in my case LOW on my 2 range N.H. and LOW on my 3 range Kubota) but after that there is nothing to worry about. I could not even imagine doing any loader work on my slopes with a gear machine.
_RaT_
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Doc, I use my L3830 with HST here at my place. I am in the Sirerra Foothills and as the name implies, it is hilly. I use my HST in medium for everything until I put on the boxscraper and put the rippers down, then I change gears by going to low range. There are a few other times I need low range. L is 0 - 4 mph, M is 0-7.5 and H is 0 -17 mph. The ranges work well for this tractor and the various things I do.
I also use a NH 2120 and a Kubota L4850 routinely, again, both in the foothills. Both are shuttle shifts and have larger engines. The Kubota is an 8X8, the NH a 12X12. When using a box scraper with the rippers down, both require low gears. The Kubota works best in 2, the NH in 3. I find the biggest drawback is in loader use where you in location A and need to get to point B. When moving 3 or 4 truck loads of topsoil, you still need to use the lower gears to get into the pile and heap your bucket, but then shift your range lever as well as you gear selection lever to get to 5 or 6 to deliver the material. You do have to be stopped to change the range selector on both. UPshifting is easy within the same range. If you have a hill with any climb, you need to drop back down etc... With my HST, I will go from L to H or M depending on the distance. M will climb most hills with a bucket load, H will not climb hills but works well on small grades. All in all, they all work well some with just a little less work. As far as shifitng gears on the shuttles, I do it for long distances, from 4th to 7th on the Kubota, the NH is trickier with its funky gear selector on the column.
I also use a NH 2120 and a Kubota L4850 routinely, again, both in the foothills. Both are shuttle shifts and have larger engines. The Kubota is an 8X8, the NH a 12X12. When using a box scraper with the rippers down, both require low gears. The Kubota works best in 2, the NH in 3. I find the biggest drawback is in loader use where you in location A and need to get to point B. When moving 3 or 4 truck loads of topsoil, you still need to use the lower gears to get into the pile and heap your bucket, but then shift your range lever as well as you gear selection lever to get to 5 or 6 to deliver the material. You do have to be stopped to change the range selector on both. UPshifting is easy within the same range. If you have a hill with any climb, you need to drop back down etc... With my HST, I will go from L to H or M depending on the distance. M will climb most hills with a bucket load, H will not climb hills but works well on small grades. All in all, they all work well some with just a little less work. As far as shifitng gears on the shuttles, I do it for long distances, from 4th to 7th on the Kubota, the NH is trickier with its funky gear selector on the column.
EastTexFrank
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</font><font color="blue" class="small">( <font color="blue"> Do you have to stop to change gears to get extra torque to go up hills, then stop to change gears to get the extra speed on flatter areas? </font> )</font>
Yup. On a straight gear tractor that's what you have to do if you need to keep the rpm within a specific range (for mowing). A synchro-shuttle is better but there is sometimes a "dead" spot when the transmission is shifting that will cause the tractor to slow down or even stop or roll back a little on hills before it engages that can cause your heart to miss a beat. Give me HST every time. You have much more control, going up or coming down hills, while still maintaining PTO rpms.
To me, the loss of PTO hp with a hydro is a non issue. If you need a specific PTO hp, then that's what you buy whether it's geared or hydro. If you have to step up one size compared to a gear tractor .... so what.
Yup. On a straight gear tractor that's what you have to do if you need to keep the rpm within a specific range (for mowing). A synchro-shuttle is better but there is sometimes a "dead" spot when the transmission is shifting that will cause the tractor to slow down or even stop or roll back a little on hills before it engages that can cause your heart to miss a beat. Give me HST every time. You have much more control, going up or coming down hills, while still maintaining PTO rpms.
To me, the loss of PTO hp with a hydro is a non issue. If you need a specific PTO hp, then that's what you buy whether it's geared or hydro. If you have to step up one size compared to a gear tractor .... so what.
DocHeb
Veteran Member
For example, a semi-truck can have 13 or more gears, and each one is effective in only a very narrow engine rpm/torque/ground speed ratio. A semi going up and down hills is shifting constantly and can have wide swings in ground speed. With gear tractors, are the gearing ranges more flexible and cover a wider range, and can you change gears on the fly without stopping?
I guess the best answer you can give me is that you have a gear tractor and have no problems with hills. /forums/images/graemlins/grin.gif
I guess the best answer you can give me is that you have a gear tractor and have no problems with hills. /forums/images/graemlins/grin.gif
