I'm looking at purchasing a B2400. The specs online suggest the tractor is rated at 24HP and the PTO is rated at 18HP. Why is it derated? and is this a common practice? I thought that the PTO power would be at the same HP as the tractor...
B2400 pto hp
- Thread starter mink
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Billdog350
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Kubota L3710 HST,L2230A QT,forks,Takeuchi TB125, 60" Luck Now pto Snowblower
Mink, there are parasitic losses from gears, seals, water pump, alternator, bearings and hydraulics by the time the "horsepower" gets from the flywheel to the PTO shaft.
On the B2400, there is also a HST unit that is basically a large hydraulic pump and motor that makes the tractor move. Pumping those hydraulics also causes a parasitic loss.
Kubota has calculated/tested that the HST system plus driveline losses = 6hp. You would likely find if they made a gear drive B2400 (which I don't think they did) it would be rated somewhere around 22-21hp at the PTO.
While you lose more HP with a HST, you make it up with the ability to "infinitely adjust" your travel speed to match the implement load and keep the engine from bogging.
I have used my little B9200 tractor, 22.5 flywheel hp and only 16pto hp to drive a 60" snowblower that should have had a minimum of 20+ hp to run...I plowed 1-2' of snow without much issue, though I did have to slow down a little at times when the engine bogged.
On the B2400, there is also a HST unit that is basically a large hydraulic pump and motor that makes the tractor move. Pumping those hydraulics also causes a parasitic loss.
Kubota has calculated/tested that the HST system plus driveline losses = 6hp. You would likely find if they made a gear drive B2400 (which I don't think they did) it would be rated somewhere around 22-21hp at the PTO.
While you lose more HP with a HST, you make it up with the ability to "infinitely adjust" your travel speed to match the implement load and keep the engine from bogging.
I have used my little B9200 tractor, 22.5 flywheel hp and only 16pto hp to drive a 60" snowblower that should have had a minimum of 20+ hp to run...I plowed 1-2' of snow without much issue, though I did have to slow down a little at times when the engine bogged.
85Hokie
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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Billdog350 said it well !
Back in the old days - a car could have 350 HP on a dyno, but at the rear wheels it would be at least 10% less. The movement of parts sucks up some of the HP.
Now when you talk about HP of an engine, unless it was dyno'ed - it talks about brake HP, that HP that can be measured at the wheel not that of the engine
Back in the old days - a car could have 350 HP on a dyno, but at the rear wheels it would be at least 10% less. The movement of parts sucks up some of the HP.
Now when you talk about HP of an engine, unless it was dyno'ed - it talks about brake HP, that HP that can be measured at the wheel not that of the engine