Does engine HP affect driving power

super55

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Jan 27, 2012
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806
Location
Great North of Michigan
Tractor
Oliver Super55, John Deere 4310, John Deere 4400, Kubota L2500 (had)
Years ago tractors used to list drawbar power which essentially gave a rating at how well the tractor could maintain momentum under load. Hydro tractors are incredibly easy to use and for loader or work that has constant F/R or finesse work they win hands down. Plus the ease of use is well liked.

The one spot where they fall flat is drawbar power. A gear shift or a power reverser tractor will run circles around a hydro in pulling of similar hp. The kubota L2500 DT (25hp) I had will out pull my JD 4400 hydro (34hp) at a higher speeds. With a hydro you loose all the centrifugal force from the engine/flywill to help drive the tires because there's no solid connection. You are moving by fluid flow. If the fluid isn't flowing as fast as it should then the system goes into relief to save the pump.

If your heart is not committed on hydro I would recommend trying a couple sizes with a direct drive transmission. If heart is set on hydro then hp is your best option for better performance.
 

chim

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Apr 7, 2002
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Location
Lancaster County, PA
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Kubota L4240, Ford 1210
When I was looking for a larger tractor in 2012 (had a Kubota B7500 then) I went to try out a privately owned Bobcat CT350. I took it for a spin down the road and back. It seemed really sluggish on the hill in HI even though it had an extra 14 horses. It seems that the HI selection on a 3-range hydro is more of an overdrive for running on the level. Ended up with an L3200 then.

The L4240 is the first tractor I've had where HI is useful. With the HST+ I can mow in HI and toggle from Rabbit to Turtle for going up grades. When roading it to town there's a hill that I need to back off the hydro pedal, but it will make it in HI Rabbit most of the time. Speed does drop a couple MPH's. This Winter with the 8' plow on the front and a 55 gallon concrete-filled barrel on the rear I did bump it down to HI Turtle for the hill.
 

CobyRupert

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Oct 30, 2012
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5,021
Location
Washington County, NY
Tractor
JD 5075E
Horsepower is just a measure of how FAST you can perform a task like climb a hill.
Assuming you had slow enough “gears”, you could have a 1 horsepower motor and still climb the hill. ...but it might be 40 times slower than having 40hp.
Like others say, the hydro pedal is not a gas pedal. You don’t mash it down when you need more torque, you lift up to go slower.
 

RalphVa

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Dec 19, 2003
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7,018
Location
Charlottesville, VA, USA
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JD 2025R, previously Gravely 5650 & JD 4010 & JD 1025R
My father in law let's me use his 25hp HST tractor quite often. Some of it's use is maintaining the road we live on. It really struggles going up any kind of hill especially with a load of gravel. I know the engine hp doesn't affect lift capacity because it's really based on what the hydraulic pump can do. But what about a HST transmission. Really not that familiar with how those work. Are they hydraulically driven. Basically I'm asking about it I buy a tractor and get a 40hp or so engine will that alleviate the issue of not being able to pull hills very well
With HST, you can rev it to get the hp needed and push the HST pedal enough to move. You won't get the full 25 hp unless you're up around 3,000 rpm. You cannot just ticka ticka ticka around like you apparently want to with a 40-50 hp tractor.
 

Egon

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Aug 14, 2001
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21,829
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Nova Scotia, Canada
HP makes the wheels go round. HP makes the hydraulic pumps produce a flow rate that is acceptable.

It’s all about HP.
 

sea2summit

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Mar 6, 2012
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Location
Left coast of, GA
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Kubota 1860->25D, MX5800, M4D
Thanks for all the input. For those that asked have been trying to decide on which Orange tractor to get the L series has the 25hp 33 and 39. All the same frame. Just wantframe make sure I wasn't paying extra for the extra hp if it didn't help
If you're looking at the 39, price out an MX. You'll be shocked how close they are.
 

sea2summit

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Left coast of, GA
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Kubota 1860->25D, MX5800, M4D
Buy a HUGE tractor and gradually work your way down. It's funner that way! That way you realize what you are missing and may want in capability.
This also get's around the whole "well a little bigger tractor will probably fit" conundrum because you'll run into all of that stuff in the first 20 hrs and as you downsize you'll never hit it again. When you go the other way you seem to hit the same things with every new tractor until you move them "that much" farther away.
 

big bubba

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Mar 7, 2007
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arkansas
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M 8540
one way of looking @ HP might be to accurately access the right model HP for your current & future needs....then step up to the next higher HP model to accommodate the HP loss robbed by HST during use, esp on hills. just a thought
think the MX suggestion by see2summit is a good one
 

hube2

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Sep 4, 2020
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Paris, NY
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Masey Ferguson GC1725M
I gave my old JD Lawn Tractor to my FIL when I got my new tractor. I've been trying to explain the HST in it to him for nearly a year. He keeps complaining that when he's going up hill he seems to loose power and it has a hard time no matter how hard he pushes on the peddle. He's convinced there's something wrong with it. I had a new HST put in it the year before I gave it to him, nothing wrong with it except the old dog in the seat. :)
 

kthompson

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Sep 12, 2008
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3,275
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South Carolina
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Kubotas B2710, M6800, L6060 cab, Volvo EC excavator, 2 ZTRs and various implements.
Yep. There's a reason my 3200 lb sedan has a 200 HP engine while my ~3500 lb tractor+FEL struggles up hills with a 33 HP engine. It takes a lot of horses to climb hills at any decent speed and weight makes all the difference.

Just for grins: mathematically, it requires 9.4 HP for that 3500 lb tractor to climb a 10% grade at 10 mph. Add 1000 lbs to the bucket and a 500 lb box blade for ballast, now it's 13.4 HP. And that's not considering tire friction, transmission inefficiencies or anything else. Hill climbing's tough for tractors unless you're going sloooooow!
Doc, so glad to see you move the topic off only tractor to point out this is not an issue with tractors. I own a Kubota B2710 with hst and recently sold my JD with 91 hp and manual transmission. We don't any real hills but we do have some reasonable slopes here. I also have a L606 with hst Kubota. We have a decent slope on our road I have run each of these tractors on along with my M6900 Kubota with manual transmission. So two manual trans and bigger engines and two with hst and small engines. Each one of those tractors slow down running up the grade. With load or without load. Of course the load would increase how much it slowed down.

As Doc pointed out, the same is true with vehicle. Just think about the "truck only" lanes on steep grades of even bridges and interstate. The slope or grade test that is most important is going down the slope. Is your tractor heavy and even brake power to control the load.

If you want another simple test get a 10 speed bike and see how it handles the grades...when I use to ride one soon learned how to down shift or strain very hard on slopes.
 
 
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