Is PTO power the same as Tractor HP?

[Scotty370]

In my project in the Build it Yourself forum, I'm going to use a gearbox on an PTO driven grinder. If my compact tractor (JD 4200, 26hp) is hooked to it, do I have a margin of over-build using a 40HP rated gearbox?

 

[bx23barry]

More than enough

 

[Dmace]

PTO power is always less than engine hp due to heat, hydraulic, and friction losses. Typically a gear tractor looses about 10% hp to the PTO and a hydro tractor looses about 25%. These are rough estimates and dependent on many factors.

 

[tallyho8]

Tractors manufactured for use in Japan are rated in pto horsepower but tractors manufactured for sale in the US are rated in engine hp.

My Yanmar YM1802 was made to sell in Japan and is rated at 18 pto hp but the engine hp is approximately 22.5.

 

[schmism]

Typically a gear tractor looses about 10% hp to the PTO and a hydro tractor looses about 25%.

almost got it right.

Most hydrostatic TRANSMISSION tractors (if not all) use a direct connection to the engine for the PTO (via clutch). the reason the PTO speed goes up and down based on engine RPM. therefore the HP diff between PTO and engine numbers is the same for both a gear and hydro (or shuttle shift, automatic, power trans etc) transmission tractors

what your thinking of (in the 20% loss) is when it comes to putting HP to the ground via the transmission. the hydro has a greater loss in converting the mechanical engine rotation to hydraulic fluid back to mechanical motion. with the trade off of infinite ground speed control and shock protection.

 

[Botabill]

In my project in the Build it Yourself forum, I'm going to use a gearbox on an PTO driven grinder. If my compact tractor (JD 4200, 26hp) is hooked to it, do I have a margin of over-build using a 40HP rated gearbox?

My 26 HP Kubota produces 19 HP at the PTO.

 

[SnowRidge]

Maximum engine horsepower is typically produced at a higher RPM than PTO speed, so PTO horsepower will automatically be a little bit less than engine horsepower. Any mechanical losses in the PTO system will lower it even more.

Manufacturers generally provide both ratings.

 

[MtnViewRanch]

almost got it right.

Most hydrostatic TRANSMISSION tractors (if not all) use a direct connection to the engine for the PTO (via clutch). the reason the PTO speed goes up and down based on engine RPM. therefore the HP diff between PTO and engine numbers is the same for both a gear and hydro (or shuttle shift, automatic, power trans etc) transmission tractors

what your thinking of (in the 20% loss) is when it comes to putting HP to the ground via the transmission. the hydro has a greater loss in converting the mechanical engine rotation to hydraulic fluid back to mechanical motion. with the trade off of infinite ground speed control and shock protection.

I'm hot sure I follow you, I just checked Mahindra 3215s. Both tractors have 32hp. The gear shows pto to be 27hp and the HST shows 25hp, both reach 540rpm at 2376rpm. How do both of these tractors have the same pto hp? Is this not similar on most tractor comparisons of this type? Yes the loss is because of the HST, but it is still a loss, the gear tractor always has more pto hp.

Am I wrong here?

 

[638]

The HST pump runs all of the time absorbing some of the available horsepower. Thus, less HP at the PTO.

 

[MessickFarmEqu]

The HST pump runs all of the time absorbing some of the available horsepower. Thus, less HP at the PTO.

This is correct, whoever said PTO HP between gear and hydro is the same is wrong.