A question of Horse Power

cchoate · Jun 17, 2005

I have been comparing tractors for months and have seen manufactures stating gross and net HP on their machines. What does it mean, what's the difference between the two?
/forums/images/graemlins/confused.gif

frank_f15 · Jun 17, 2005

From what i can figure different manufactures mean different things by Gross hp and NET HP . i feel Gross HP is what the engine will actually put out and net HP IS WHAT YOU GET at pto, this all depends on type of tranmission. mabey somone more knowlegable than i can explain it better.
Btw i am just south of Buffalo myself, check out the MEETINGS AND GET TOGETHER FORUM WNY CHAPTER we are getting together on july 9th. if you are interested?

johnk · Jun 17, 2005

I don't see any WNY forum.........Where is it???

DHennet · Jun 17, 2005

The name of the forum is Meetings and Get togethers. It's toward the bottom of the discussions page.

cchoate · Jun 17, 2005

I love Earls, it's about an hour for me but worth it. I live over by Darien Lake. How long do the meetings last or is it just an informal get together?

The meetings forum is new to me, it's been a while since I have been on the board. Now that I'm moving up in the world (B7500 to a L3430) I'm back and good to be here.

johnk · Jun 17, 2005

I have been on here over a year and never clicked on the + sign to open those boards......Thanks.......

hobbyfarm · Jun 17, 2005

cchoate,
Hola, fellow telecom tech. Near as I can tell you,

The gross horsepower rating (and the torque rating) is taken at the flywheel with a bare engine (no accessories). I've read that some brands do use accessories such as alternator and water pump, etc. on an engine that's ready to drop in a vehicle and others use just bare block.
Where PTO hp rating is taken at the PTO shaft on a vehicle that is ready to go to the field, which, of course subtracts the load of various entities within the transmission.

Various manufacturers test to different SAE or ASAE standards.

There are forums where you can research the topic here:
American Society of Agricultural Engineers
or
Society of Automotive Engineers
Keep in mind that these organizations sell these standards and what you read in the forums will be anecdotal, kind of like here.

Clear as mud, right?
Phil

Bob_Skurka · Jun 17, 2005

Horsepower, Gross: The power of a basic engine at a specified rpm without alternator, water pumps, fan, etc. Gross horsepower is the figure commonly given as the horsepower rating of an engine.

Horsepower, Net: The usable power output of an engine "as installed." Net horsepower is the gross horsepower minus the horsepower used to drive the alternator, water pump, fan, etc., at a specified RPM.

Horsepower, PTO: The useable power output available at the PTO shaft to drive an implement. PTO horsepower is the net horsepower minus the horsepower lost to the transmission at a specified RPM.

DmansPadge · Jun 18, 2005

(

Horsepower, Gross: The power of a basic engine at a specified rpm without alternator, water pumps, fan, etc. Gross horsepower is the figure commonly given as the horsepower rating of an engine.

Horsepower, Net: The usable power output of an engine "as installed." Net horsepower is the gross horsepower minus the horsepower used to drive the alternator, water pump, fan, etc., at a specified RPM.

Horsepower, PTO: The useable power output available at the PTO shaft to drive an implement. PTO horsepower is the net horsepower minus the horsepower lost to the transmission at a specified RPM.)

Bob always knows best! How does Bob know so much anyway?? /forums/images/graemlins/confused.gif

JerryG · Jun 18, 2005

Bob,
I agree with everything that you said except:
 PTO horsepower is the net horsepower minus the horsepower lost to the transmission at a specified RPM.

When the PTO hp is tested, it is tested with the tractor stationary. I don't how much hp lose a hydro would have when the tractor is stationary because of the transmission, but a manual doesn't lose any hp to the trans. if the tractor is not moving.