Will 10 Horsepower actually matter on the same size tractor?

[finn1]

Ram pickup engines.

6.4 L gas has 410 HP and 422 ft/lb torque.

6.7 diesel has 370 hp and 850 ft/lb torque.

The diesel has higher towing capacity even though it has less HP.

Try 420 hp and 1070 ft lb for the HO version. That’s over twice the torque of the gasoline engine.

Of course you need to specify the optional transmission to handle the torque.

 

[Cahaba Valley Farm]

Try 420 hp and 1070 ft lb for the HO version. That’s over twice the torque of the gasoline engine.

Of course you need to specify the optional transmission to handle the torque.

If this is possible then why is the PTO hp on all the tractors less then the engine hp?

 

[LD1]

If this is possible then why is the PTO hp on all the tractors less then the engine hp?

Was this being sarcastic or a rhetorical question? Or where you being serious?

 

[finn1]

He’s probably serious.

Answer is friction losses in the geartrain. Meshing gears generate heat, and bearings have drag, and gear lube is viscous. That’s all energy that can’t be used to do work.

 

[Cahaba Valley Farm]

He’s probably serious.

Answer is friction losses in the geartrain. Meshing gears generate heat, and bearings have drag, and gear lube is viscous. That’s all energy that can’t be used to do work.

But in reality PTO hp is just torque correct?

 

[mo1]

But in reality PTO hp is just torque correct?

No. Horsepower is torque multiplied by speed, specifically, (torque*RPM)/5252.

 

[LD1]

No. Horsepower is torque multiplied by speed, specifically, (torque*RPM)/5252.

In a round-about way he is correct. Because PTO HP is always measured at 540RPM.

So a tractor with 50 PTO HP is always gonna be 486ft-lbs of torque.

A tractor with 25PTO HP is always gonna be 243ft-lbs.

 

[RickB]

In a round-about way he is correct. Because PTO HP is always measured at 540RPM.

Except for those that aren't. Tractors larger than those primarily discussed here are usually rated using 1000rpm PTO's. Many of these only offer 1000 rpm PTO.

 

[Cahaba Valley Farm]

In a round-about way he is correct. Because PTO HP is always measured at 540RPM.

So a tractor with 50 PTO HP is always gonna be 486ft-lbs of torque.

A tractor with 25PTO HP is always gonna be 243ft-lbs.

Ooh interesting...I have never had anyone break it down like this before. If you don't mind me asking how do you know this? Could you share the math that was used to reach this understanding?

 

[mo1]

Ooh interesting...I have never had anyone break it down like this before. If you don't mind me asking how do you know this? Could you share the math that was used to reach this understanding?

The formula is in my post, horsepower = (torque*RPM)/5252. Applying seventh-grade algebra, torque = (horsepower*5252)/RPM.

@LD1
The reason I didn't specifically put any RPM value in the equation I posted is that there are actually four standard rear PTO types according to the ISO and ASABE and only one of them spins at 540 RPM. Type 1 is the six-spline 1 3/8" 540 RPM PTO that is on most compact and utility tractors. The other three standards use different, higher RPMs. Type 2 is a 1 3/8" 21 spline PTO spinning at 1000 RPM and is seen as an option on many full sized utility tractors and small row crop tractors. Type 3 is a 1 3/4" 20 spline PTO spinning at 1000 RPM and is on large row crop tractors. Type 4 is a 22 spline 2 1/4" PTO spinning at 1300 RPM. We also have nonstandard mid PTOs spinning at other, typically higher RPMs (generally 2000-2500 RPM). All of those will have different (lower) torque figures for the same horsepower ratings as compared to 540 RPM.