Rated HP vs Net

[CobyRupert]

Gross engine horsepower is how much is put out by the force of the cylinders pushing on the crankshaft through the connecting rods.
Net engine horsepower is how much is left over after running accessories such as the water pump, alternator, etc.
PTO horsepower it is how much horsepower makes it through the transmission and out to the PTO.
PTO horsepower will be less on hydrostatic tractor then on the same model gear driven tractor as the hydrostatic transmission is always pumping some fluid in the low pressure circuit to keep the high pressure pump for the hydrostatic transmission from starving.
Calculated PTO horsepower is likely using an estimate of how much horsepower the transmission loses for parasitic losses.
Observed PTO horsepower is likely from putting the tractor on a PTO dynamometer and seeing how much horsepower it puts out through the PTO.
Aaron Z

Thanks for the explanation. I've always heard that some engine ratings are the engine "bench test" without the additional "load sucker" accessories, factory exhaust, etc...
PTO horsepower is a good indication on what you'll actually get.

Nobody uses bHP (brake horsepower) measured at the wheels anymore? Not even the Nebraska tests? This would be a good indication too, especially on hydros.
Which begs the question: Is the loss to the PTO the same as loss to wheels on a hydro? On a gear? More or less?

 

[ericm979]

The PTO is not driven through the HST so there's no loss there. But there is a small extra loss as explained above because the HST is still pumping some fluid. You see that in specs of gear vs hst versions of the same tractor where the gear model has a few more PTO HP. For example a Kubota L4060 gear has 34 pto hp while the HST has 32.5. Both have 42 gross hp and 40 net.

Brake HP is just dyno HP- a brake is a type of dyno. So it could be measured at the engine or PTO. The old car SAE standard used back in the mucle car days allowed removing accessories, mufflers and air cleaners and was at the engine, so it resulted in artificially high numbers.

 

[CobyRupert]

The PTO is not driven through the HST so there's no loss there. But there is a small extra loss as explained above because the HST is still pumping some fluid. You see that in specs of gear vs hst versions of the same tractor where the gear model has a few more PTO HP. For example a Kubota L4060 gear has 34 pto hp while the HST has 32.5. Both have 42 gross hp and 40 net.

Brake HP is just dyno HP- a brake is a type of dyno. So it could be measured at the engine or PTO. The old car SAE standard used back in the mucle car days allowed removing accessories, mufflers and air cleaners and was at the engine, so it resulted in artificially high numbers.

Good info.
So.....is there no info on the horsepower the gear tractor can put on the ground (wheels) versus the hydro?

 

[jeff9366]

Doesn't bode well for being able to negotiate on prices.

Most years Kubota factory incentives are most generous, and fall on a wider assortment of equipment in the Spring.

For the last two years we have been in a period of fairly rapidly rising machinery prices due to tariffs, steel price increases and a strong market for new tractors <80 horsepower. I speculate net machinery prices escalated 5% per year in 2017 and 2018.

The marketing tactic of increasing prices during periods of strong demand, then discounting back a portion of the price increase as a limited time incentive, is as old as marketing itself.

Ponder the cost of waiting.

British Columbia is on the coast. There should be numerous dealers for you to negotiate with within 100 miles once you finalize options.

 

[Sawyer Rob]

I guess it really depends on the individual owners needs. I rarely use the PTO and when I do, it's usually for something that doesn't need a lot of HP. The only thing I need PTO hp for is the snow blower and I didn't even need to use it this winter. For me the biggest need for power is when pulling the boxblade or pushing the snow plow uphill. Even just traveling up my driveway it would be nice to have a little more HP so I could travel a bit faster.

Well, MY experience is, if it's got more to the pto, it's got more to the ground.

So, for me, pto hp is the most important...

SR

 

[Hilbilly]

Well, MY experience is, if it's got more to the pto, it's got more to the ground.

So, for me, pto hp is the most important...

SR

Good point!

 

[finn1]

No way are you going to get an accurate assessment of power by driving an unladen tractor around the dealers lot. You will need to hook up ground engaging equipment at the very least.

Driving an unloaded tractor will, at best, give you an idea of the gain calibrated into the throttle, ie governor response, but not actual usable horsepower.

One of the tricks calibrates use, particularly in cars and trucks is to front load the throttle progression curves to increase perceived power in the first few degrees of throttle progression. It makes the vehicle feel peppy because a little throttle really makes the vehicle jump as perceived in a typical around the block test drive. Problems arise when that same pedal calibration makes the vehicle all but undriveable off road.

Pull a load up a hill and that peppy calibration is no better than a standard calibration.