Oil & Fuel Diesel Tractor HP vs. ATV or Car

[VTSasquatch]

Oh yeah, the way I think I understand the issue now is that a low torque/high RPM engine may be able to be geared way down to move a 10 ton machine but that it would have to be geared so low that it would not be a practical choice and it would have to move very slowly. A torquey engine can be geared higher and, therefore, run at lower rpms to run a tractor. The main reason for the same HP is the ability to generate very high rpms (for a short period of time or it will wear out) with less torque in an atv engine.

Now there is a difference in functional HP in gas versus diesel? Oh no!

 

[Charlesaf3]

The ATV was stolen in VT? I'm shocked and disappointed to hear that. God that's infuriating.

As I understand it (many here clearly understand it better) the torque curve is better for diesel - that is to say diesel develops more low end torque than gas.

 

[RobJ]

I did read the article Moss. Thanks. I got lost though when the author talked about the water wheel. I don't really understand why all that torque couldn't be geared to turn a shaft faster without the huge loss of energy. Or why a fast motorcycle engine couldnt be geared down to produce more torque at the wheel. Anyway, I think I get the jist. Apples and oranges. One is made for one task and one for another. I used my atv to pull a 500 lb disc harrow and it could move it well. I am sure a tractor would be better though.

The atv was stolen overnight so I won't be able to compare them side by side. The worst part is that I'm told that my homeowners insurance won't cover it. It was a $7K machine with only 300 miles on it. I hate theives too! (saw the other thread.)

In high school physics my kids are learning about hp, gearing, and what will and won't work. Google mouse trap car.

Bummer about your ATV. they are separate because they have a VIN if i recall. My 2 are insured that runs me about $200 a year. I keep them in a locked garage chained together. Just in case.

Good Luck,
rob

 

[Iplayfarmer]

I read the article. Great explanation!

Here's my question about Horsepower...

How come my old '69 John Deere 140 at 14 HP seems to out work the neighboor's shiny new 20 HP Craftsman? There's got to be a difference in measuring Horsepower there.

 

[Patches]

If yours' is a gear or hydrostatic and his is belt driven, the answer is clear

 

[Z-Michigan]

I read the article. Great explanation!

Here's my question about Horsepower...

How come my old '69 John Deere 140 at 14 HP seems to out work the neighboor's shiny new 20 HP Craftsman? There's got to be a difference in measuring Horsepower there.

Yeah, uh, I've got a JD 5105 rated for 50hp and a MTD Yardman mower rated 20hp (gas briggs & stratton). The mower is decent for mowing, but there's no chance in (anywhere) it will do 40% of the work that my JD diesel tractor will do.

The drive system is part - HST in the mower vs. gear in the tractor - but HST CUT's can do fine. As unscientific as this sounds, there are differences in horses between different engines and purposes.

Now, if the Yardman had the gear system of a Ford 8N, then maybe it would do closer to 40% of what my JD does...

 

[jmfox]

HP at a limited rpm range puts less stress on a system. As the range of power increases, the engine must be able to handle the strain. Tractors have huge cranks etc. They can produce more horse power throughout a wider range. The sport bike might have a spike at 7,500 rpm, but it is fleeting and depends on momentum etc.

jmf

 

[slaveToHorses]

Yeah, uh, I've got a JD 5105 rated for 50hp and a MTD Yardman mower rated 20hp (gas briggs & stratton). The mower is decent for mowing, but there's no chance in (anywhere) it will do 40% of the work that my JD diesel tractor will do.

The drive system is part - HST in the mower vs. gear in the tractor - but HST CUT's can do fine. As unscientific as this sounds, there are differences in horses between different engines and purposes.

Now, if the Yardman had the gear system of a Ford 8N, then maybe it would do closer to 40% of what my JD does...

Actually, the MTD/B&S engine is basically a small tractor engine. It has a long stroke and large diameter crank, for it's displacement. It is designed to generate peak HP and torque at low rpm. So yes, given the correct gearing, it could work in a real tractor (frame issues aside). In the lawn mower, it has a belt drive cheesy transmission and no weight so the mower doesn't make a good tractor. Of course if you put it in too large a tractor and you would likely break the crankshaft...

Some ATV engines are built more like tractor engines than they used to be. There are ATVs that are marketed as farm chore vehicles. But the true tractor and tractor engine is still designed heavier, larger, stronger and slower. It's a different design target.

 

[Reg]

Torque is turning force (force times distance).
Power is "rate of doing work", or force times speed.

One Horse Power is 746 Watts (from memory, but that is close) or some number of ft pounds per second (that I really do NOT remember, but would recognize from lo skool phys class).

 

[john_bud]

Mr Watt based his HP number on how much coal a horse could pull out of a mine. I think it was 550 pounds 1ft vertical in 1 second.

Here are 2 things you have to KNOW to compare power plants. 1 is HP the other is RPM where that HP is generated.


As was previously posted, tractors are usually rated in continuous HP. That is the power they can deliver hour after hour after hour for years at a time. Cars, ATV's etc are rated at instantaneous peak hp. That is just like it sounds, the optimum best case and not sustainable. It's because there is a bigger marketing influence in consumer goods than real AG goods. And farmers really care about things like PTO hp because they actually USE it.


Bottom line on tractors is to compare PTO hp, that levels the playing field.

jb