how much power does hst use vs gear

[1pizzahead]

:cool2: Ive been told a hydro transmission steals 12-15hp on a 30-40hp tractor. I'm looking at Kubota L3800 and NH Boomer 40 tractors. Does anyone know if this is true. I've also heard about a Boomer 30 hst not being able to pull a 2 bottom plow and the guys old junker gear 12 hp could. Any help? thank you:dance1:

 

[texasjohn]

I don't believe that there is any science behind the kind of power loss you have been told.

I have an HST and believe maybe one HP is what it takes. Yes, HST takes a small % of HP, but nobody these days using a 55 HP or under tractor puts a plow in the ground for sufficient hours in a year for that to be a factor in fuel saved. As far as traction and pulling power, a properly sized tractor/implement match will get the job done...gear/gst/HST does not matter.

HST is IMHO easily the winner when it comes to reduced operator fatigue and extreme precision operation and back/forth operations.

 

[crazyangel]

When I was shopping last year the data sheets I remember showed a 2-3 hp debit for HST.

EDIT: I went back and looked at some of the literature I have for a Kubota MX5100, and the published loss is 1.5 HP on a HST vs a geared transmission. YMMV.

 

[MHarryE]

The 2 - 3 HP debit for the HST is only for the extra power required for the HST charge pump which is always running to supply control pressure for the HST control plus make sure the piston pump always has a pressure oil supply and also oil to cool exchange in the high pressure loop so the hot loop oil can be cooled. The HST efficiency varies with pressure, pump swash plate angle, motor swash plate angle among other things. Hydros gain their efficiency in speed and direction control.

 

[crazyal]

People come up with information based on what they heard, not fact. The hydraulic pump for the HST drive does require HP to operate it, the numbers I've seen are anywhere from 1hp to 3hp. Then there's the issue with pressure, but the pressure is a direct result of traction and resistance to moving. The same is true for a gear tractor though. If you lift the tires off the ground then it will require no HP to turn the wheels but if you hitch it up to a large load then it will require a lot of HP.

The fact is that you are not going to run out of HP with a boomer 30 trying to pull a 2 bottom plow. You're either going to loose traction and spin your tires or you are going to pull it so slowly that the plow will not turn over the soil because you're not going fast enough. I've never tried to pull a plow but I'm guessing that pulling a 2 bottom plow with any 30hp CUT is going to be at it's limits. With the right soil it could be done. My best advise is if you are thinking about a Boomer then go to the New Holland section and ask specific questions. Tell them what you want to do. If plowing tell them the type of soil you have and the last time it was worked. Stop worrying about numbers on a piece of paper.

 

[jeff9366]

Does your tractor, or your proposed tractor, have an FEL?

If you will be doing a lot of forward/reverse work, as in operating an FEL, you will want an HST.

If you will primarily be pulling dirt engaging implements in straight lines over large fields, requiring minimal reverse time, a geared tractor may be appropriate.

 

[jeff9366]

I've also heard about a Boomer 30 hst not being able to pull a 2 bottom plow and the guys old junker gear 12 hp could.

Plow and other pulling capability is a factor of tractor weight, tractor horsepower, and tractor traction. Tractor weight is a considerable factor. A Kubota L3800 is a medium weight tractor, around 2650 pounds, and should be capable of pulling a 2-12 two bottom plow, which would normally be adjusted to plow 6" deep. Keep in mind it is easier to plow after a good rain when the soil is less resistant.

I am less certain an L3800 would pull a 2-14 two bottom plow satisfactorily.

Traction is a factor of tires, 2-WD or 4-WD and the ground you are pulling over.

Older tractors did not have much horsepower but had heavy frames and were universally outfitted with aggressively ribbed agricultural tires. The Ford 8N was 24-hp, I believe. Plowing was a high priority then, less so today. Today I believe more PT0 powered tillers, rather than plows, are used for soil preparation with compact tractors.

A high proportion of compact tractors sold today are purchased with FEL's; tractor/loaders are usually sold with industrial tires which are wider to support front end loads in the bucket and are more puncture resistant but provide less traction in the field than R-1 ag tires.

 

[alchemysa]

I have no idea of the HP loss of a HST but I'd suggest the stats are coming from the tractor manufacturers themselves and apply to brand new HST's in perfect condition. So I'd take those stats with a grain of salt myself.

Geared tractors don't lose power as the transmission gets 'older'. On the other hand, a tired HST can barely climb over its own shadow.

 

[Baby Grand]

:cool2: Ive been told a hydro transmission steals 12-15hp on a 30-40hp tractor. I'm looking at Kubota L3800 and NH Boomer 40 tractors. Does anyone know if this is true. I've also heard about a Boomer 30 hst not being able to pull a 2 bottom plow and the guys old junker gear 12 hp could. Any help? thank you:dance1:

Actual increased loss to hydro vs gear is probably closer to 1.2 - 1.5 hp on a 30 - 40 hp machine.
13.5 hp/hr would require a radiator capable of handling an additional 34,350 btu per hour (btu/h) heat rejection, forcing immediately noticeable design changes between the two machines. Since profit is improved by commonality through a product line, this wouldn't fly well with the business people.

 

[Ted Summey]

According to tractordata.com the loss is less than 2 hp at the PTO on the L3800. It varies from band to brand and model to model. In most cases the loss for HST is less than 3 hp at the PTO.

 

[case245]

i know an auto tranny in a car say a turbo 400 takes 50-60 horse power to turn so maybe 10-15 hp on a hst tractor

 

[puckgrinder85]

After having a geared tractor and a FEL I dont think i'll ever go back to that once I got on an HST, I dont even use the brakes anymore.

 

[radioman]

well-- I would like to believe that a HST is more efficient then geared. With HST, the power being used to run pump is constant - so its easier to figure out your fuel use. Of course with a geared or HST tractor if you are pushing or pulling hard the fuel use goes up - but on HST the reliefs starts to kick in at max so its constant level of poweer being robbed - of not more on a geared tractor. Just my opinion- I could be wrong though..

 

[Gary Fowler]

I have both geared and HST tractors. The small Kubota B26 with backhoe will run out of traction before it runs out of power. I think the world average is about 2 HP lost vs same tractor with gear drive. I think someone already stated that if you are doing loader work and lots of forward reverse action, and HST is the best but it you are mowing straight line in a large pasture or using tillage equipment all day long a gear drive might be more suited. The one thing I like the gear drive over the HST is that I don't have to have a foot on the GO pedal all the time and that leaves both feet free to do braking and clutching. A few HST tractors will have a clutch also and maybe one will have the brakes on the left and HST pedal on the right but most have brakes on the same side as the HST pedal so it in nearly impossible to use the breaks for steering, that is assuming the tractor has steering brakes. Some only have one brake pedal which for me would be an automatic pass by on buying a tractor but some folks don't need them. To me a steering brake on a tractor is like a concealed weapon, its not very useful until you really need it.

 

[Gary Fowler]

i know an auto tranny in a car say a turbo 400 takes 50-60 horse power to turn so maybe 10-15 hp on a hst tractor

I think this is an old wives tale from the young fools drag racing days where everyone thought a standard was the only way to go. The old turbo 400s lost as bit of power in the clutches but not nearly that much and it wasn't so much that it took that 50-60HP to turn the tranny, just lost a bit on the low end due to slippage. Todays transmissions are much more efficient.
When it comes to power loss, everything(including gear drive) looses it due to friction loss. That is what keeps the proverbial perpetual motion machine from working. The fewer gears or other apparatus that the power moves thru before getting to the final drive the less friction losses there is.

 

[avc8130]

We can use "Kubota Math" to try to extract:

L45 is basically an L39 w/ a HST+.

I have owned both. I like both. The GST and HST each have their advantages and I won't get into it. Here are some stats:

L39:
39 HP
GST
30.5 HP PTO

L45:
45 HP (Gross Power)
42.5 HP (Net Power)
HST+
32 HP PTO

With that math...

The L39 has 6 less HP but only 1.5 less HP at the PTO. What's the deal with "gross" vs "net" SAE ratings on the L45? Somewhere the HST+ is using some HP...

ac

 

[Buckgnarly]

I have both geared and HST tractors. The small Kubota B26 with backhoe will run out of traction before it runs out of power. I think the world average is about 2 HP lost vs same tractor with gear drive. I think someone already stated that if you are doing loader work and lots of forward reverse action, and HST is the best but it you are mowing straight line in a large pasture or using tillage equipment all day long a gear drive might be more suited. The one thing I like the gear drive over the HST is that I don't have to have a foot on the GO pedal all the time and that leaves both feet free to do braking and clutching. A few HST tractors will have a clutch also and maybe one will have the brakes on the left and HST pedal on the right but most have brakes on the same side as the HST pedal so it in nearly impossible to use the breaks for steering, that is assuming the tractor has steering brakes. Some only have one brake pedal which for me would be an automatic pass by on buying a tractor but some folks don't need them. To me a steering brake on a tractor is like a concealed weapon, its not very useful until you really need it.

That is a really good point I never thought about. Is the pedal for HST usually on the same side as the brakes?
My gear Kioti has cutting brakes and I never thought I would use them until this Winter....pushing snow with the FEL I discovered the GREAT steering you get from them. The front wheels are useless on the ice, but the brakes work awesome for steering!

 

[nybirdman]

I pulled a 2/12 bottom plow for 4 years with a L3130 HST 4WD Kubota with no problem.Used 4WD most of the time,this is in the rock strewn North-east.Ten acres per year.R1 tires,31.5 HP.

 

[Gary Fowler]

That is a really good point I never thought about. Is the pedal for HST usually on the same side as the brakes?
My gear Kioti has cutting brakes and I never thought I would use them until this Winter....pushing snow with the FEL I discovered the GREAT steering you get from them. The front wheels are useless on the ice, but the brakes work awesome for steering!

I use the steering brakes to keep the tractor going my direction when back dragging or going forward but just using the heel of the bucket to smooth out muddy ruts with the FEL. Without using the brakes, it tends to drift to the high side which has more drag. It is difficult with the Kubota as the brakes are on the same side as the HST pedal just as most tractors are. SOMEONE jump in here with a model where the brakes are on the left side as I know there are a few that are that way.

 

[mowin]

I use the steering brakes to keep the tractor going my direction when back dragging or going forward but just using the heel of the bucket to smooth out muddy ruts with the FEL. Without using the brakes, it tends to drift to the high side which has more drag. It is difficult with the Kubota as the brakes are on the same side as the HST pedal just as most tractors are. SOMEONE jump in here with a model where the brakes are on the left side as I know there are a few that are that way.

My JD 3320 has the go peddels on the right and the brakes on the left. I use them when back dragging also. only way to keep a straight line..