kubota vs. kioti

[SPYDERLK]

I'm not quite sure what situation you're proposing here. Are you talking about getting the engine up to full operating RPM quicker, or are you talking about intentionally running the engine at lower RPM?

The term tractability applies here. Engines having a good amt of torque rise avoid the need for exact gearing in the face of changing load when PTOrpm is not too critical. Lose a little ground speed and "torque" on thru w/o a shift.
larry

 

[SPYDERLK]

A bigger heavier gearbox and blades dont really take any more power to operate. The power required to turn just the components is peanuts in comparison to doing the work of mowing.

And sometimes the heavier blades and gearbox can help power through a thick spot, since once at speed, it has more inertia.

They take more power due more grass being cut and [a little] for greater windage losses. Theres either something wrong with the small mower or the small tractor. Could be as simple as grass discharge or blade profile differences.

 

[94BULLITT]

Yes a 8N will run a 5' but not well in deep stuff. But it's only 27 or so PTO hp correct? Now my NAA runs a 5ft ok if I stay I stay in first in thicker stuff. BUT I have to run it WOT and it's giving everything it's got. Can't say it gets pulled down to where I stop but definitely moans a lot and I Gotta go real slow. Never burns oil and has great oil pressure. My point is I don't see anyway it can handle a 6' in the same grass period but I'm going test this theory. Just need to wait a few more weeks. The 2810 on the other hand goes through same grass and doesn't seem to struggle at all even with the bigger and much more heavy gear box which in theory should require more power to operate.

You could try the 5' on the 2810 too.

 

[LD1]

I didnt realize the 2810 was such a heavy tractor until looking at the specs yesterday.

4400#, will lift 3000 on the 3PH, and only 32HP....

Put a heavy cutter on that and I bet it dont go up a hill very fast:laughing:

 

[SPYDERLK]

Yep. All calculations still apply. You can change any variable you want. Slope angle, HP, weight, etc.

Here is some more to think on.
In a typical real-world dyno, rpm(speed) will fall off quicker than HP. IE: if peak power is @ 3000rpm, at 1500 you will likely have more than half of what the peak was. Maybe 60% or so.

Why do I mention that? Simple. If you have ever driven a tractor on the road, in high gear and went up a hill. Did you notice that you might have dropped 500 rpm and then it quit falling off? That's because the speed decreases at a faster rate than power. And you reach an equilibrium point. If you don't, and rpm keeps falling, you downshift.

Its that slight upward bulge in the torque curve. It would be nice to have a good bump reasonably close to max power. RPM could then fall a little ways at constant power. Kinda hard to arrange in a passive fashion.

 

[LD1]

Just crawling through specs of different tractors, I found some other interesting things.

Ford 3610 was offered with both Gas or Diesel.
Gas Engine...44hp and 135ft-lbs of torque.
Diesel..........47.5hp and only 130 ft-lbs

TractorData.com Ford 3610 tractor engine information

And the ford 4610. This is even more interesting cause its the same bottom end. 4.4" bore 4.4" stroke 201ci

Gas..........56hp/173 ft lbs
Diesel.......60hp/168ftlbs

TractorData.com Ford 4610 tractor engine information

And on both of these, the gasoline engines made their peak torque at a lower RPM of 1100 vs 1400 for the diesel.

And here I thought the diesels always had more low end grunt and better "torque" monsters for towing:confused2:

 

[sawtooth]

I didnt realize the 2810 was such a heavy tractor until looking at the specs yesterday. 4400#, will lift 3000 on the 3PH, and only 32HP.... Put a heavy cutter on that and I bet it dont go up a hill very fast:laughing:

Yes those older fords were really built well. I actually have a friend of mine with a John Deere 990 that has 35pto hp and 40 engine hp. My 2wheel drive unit seems to out pull his in 4x4. I give him &$!@ about it every year. We pull a heavy Brown disk harrow. All I can figure is the weight diff of the two machines. He does have the R4 industrial tires though where I have ag tires. I know that's part of it but they have like new tread where mine are 1/2 way wore. Also felt 4x4 would make more diff. He seems to need to wind his out more around 2800 rpms vs me running 1600 or so. Tires seems to spin more as we'll.

 

[sd455dan]

I'm not quite sure what situation you're proposing here. Are you talking about getting the engine up to full operating RPM quicker, or are you talking about intentionally running the engine at lower RPM?

Neither- my point is a larger displacement engine that has a lower rated power rpm will produce more torque and therefore more horsepower at rpms under the rated rpm compared with an engine that has comparable horsepower at its rated operating rpm. Although the lower rpm engine should accelerate faster thru its rev range because it is producing more torque and therefore hp under the curve.

I f you compare the two graphs you will see that even though the 2000 rpm engine is actually only producing about 48 hp at rated speed compared to the Kubota which produces 50 hp at rated speed, at all operating speeds the 2000 rpm engine is producing much more torque and therefore much more horsepower at any rpm point in its operating range.

Which also means it can do more work on average than the higher revving engine -unless the Kubota is only compared while operating near or at wide open speed.

In a geared tractor configuration the engine is in many applications not running at rated speed but will have more horsepower available especially at low engine speeds - which is an advantage when pulling heavy implements from a dead stop. And many implements in real world conditions.


As i have said before i don't believe the 2000 rpm engine has an advantage in a Hydrastatic drive tractor -where the tractor is operated at peak rpm for the hydros benefit. i do believe it is an advantage in a geared tractor operating many times at lower rpms... i took a few a test rpm horsepower points on the 2000 rpm engine these are ballpark #s but at 1000rpm the 95a engine is @ 30hp the kubota isn't even on the chart but looks to be around 13 hp
@ 1500 rpm 95a @41hp kubota @34 hp
@ 1800 rpm 95a @44hp- Kubota @40 hp

I think due to epa regs and possibly manufacturing costs in materials manufacturers have cranked up the rpms on these diesels to achieve comparable hp #s using smaller and smaller displacement engines- but sacrificed some abilities the lower revving higher torque engines had in the past...

One more thing i am not intending to pick on Kubota it was just the chart already posted.
This seems to be industry wide and if the trend away from geared machines continues maybe it won't even matter because most hydro machines are operated at near rated rpms anyway... JMO and:2cents:

 

[SPYDERLK]

Just crawling through specs of different tractors, I found some other interesting things.

Ford 3610 was offered with both Gas or Diesel.
Gas Engine...44hp and 135ft-lbs of torque.
Diesel..........47.5hp and only 130 ft-lbs

TractorData.com Ford 3610 tractor engine information

And the ford 4610. This is even more interesting cause its the same bottom end. 4.4" bore 4.4" stroke 201ci

Gas..........56hp/173 ft lbs
Diesel.......60hp/168ftlbs

TractorData.com Ford 4610 tractor engine information

And on both of these, the gasoline engines made their peak torque at a lower RPM of 1100 vs 1400 for the diesel.

And here I thought the diesels always had more low end grunt and better "torque" monsters for towing:confused2:

There are some misprints I think. They gotta both be diesels judging from the compression ratios. :confused3:

 

[sawtooth]

The term tractability applies here. Engines having a good amt of torque rise avoid the need for exact gearing in the face of changing load when PTOrpm is not too critical. Lose a little ground speed and "torque" on thru w/o a shift. larry

Thanks as this is exactly what I was trying to explain earlier. The larger displacement engines normally are better at this. A lot of the older tractors had bigger derated engines with very early torque delivery. Newer compacts just don't offer this. Typically they use smaller engines to save cost and then squeeze every last bit out to meet a specified hp rating. Of the newer stuff I've tried being John Deere 990 and Kubota MX5100 they do fine when at or near rated engine speed but fall flat on their face when much below that during a heavy load. I can actually have both my Ford 2810 and 3910 at idle when I make a turn at end of a row then set in my heavy Brown disk harrow and throttle back up to speed. Both of the other tractors tend to die as they struggle trying to get back up into their comfort range. You can get around this by changing gears on the newer tractors to keep them in the rpm range they like or try to leave rpms up while turning and dropping disk. Only down side to this is more operator involvement for first option and 2nd option running engine at high rpms usually involves more jerkiness in rough terrain. I typically disk at 1400-1600 rpms and the tractor is very smooth in these type situations. Come to end of row pulling throttle down to idle lift disk, turn, and place disk in dirt while throttling back up. The Fords do this great but the other two not so well.