Power loss between engine and PTO

[EuroYanmar]

Good morning,

Yesterday I have made this excel sheet to have an idea of the power loss between engine and PTO.
I took the datas from official specifications. Some of these tractors are from european market and others from US market.
I hope I did no mistakes.

What do you think of this ?

Thanks for your help.

Phil

 

[Tinhack]

It's not clear on what "rating" you're using. There could be a substantial difference between Maximum Engine Horsepower and Engine Horsepower at rated PTO output speed. If PTO output speed of 540rpm is achieved at 1800rpm engine speed and peak engine horsepower is achieved at 2100rpm, of course there will be a loss on PTO power. I would bet the gap is reduced if the engine is run at peak output rpm. The problem is the PTO rpm may not be the standard 540rpm. (Ignoring the other speed "standards".)

There's more to it than just comparing numbers. Nice chart though.

 

[Industrial Toys]

I always wondered about the slight discrepency between Engine HP and PTO HP. I don't think it's just the driveline losses. I think the measurements are different. Some shop vacs boast 6HP plugged into a 120 volt, 15 amp outlet. Doing the normal math, will show that is impossible. Even at the full 15 amps it falls many times short, never mind that the machines only draw a fraction of the 15 amps. I hope I didn't confuse things with the electrical example.

 

[wheelbuilder]

I may well be wrong here, but not too many years back, popular science was talking fuel efficiency in cars. At the time, automatics were only about 80 percent efficient compared to a manual. Both have losses. I know things have improved, but I think the type of drive your pto has certainly impacts the output.
Check how much heat you get in the oil in your transmission (either kind of drive). That heat is a big part of your power loss.

 

[hosspuller]

Depends on how the engine HP is rated. Are all engine accessories included? alternator, water pump, fuel pump, hydraulic pump, fan, plus any I missed... Are ou comparing an end of shaft ? Strictly, PTO related, there's the transmission. even in neutral, there're losses such as the transmission pump. Plus the PTO gear reduction, Seal drag loss, etc.

Notice the PTO power difference between open station and cab units... likely the a/c compressor power.

 

[Bavarian]

OP, you got it right. Tym's are known for this discrepancy. You're not the first one on this forum ho found this. But there is an error on the data sheet of Tym that even dealers are not aware of. One of the TBN useres was insisting and some higher Ups at Tym confirmed a lower loss to the PTO. I think this also applies to some Branson models.

 

[ptsg]

OP, you got it right. Tym's are known for this discrepancy. You're not the first one on this forum ho found this. But there is an error on the data sheet of Tym that even dealers are not aware of. One of the TBN useres was insisting and some higher Ups at Tym confirmed a lower loss to the PTO. I think this also applies to some Branson models.

Wondering if that's something related to the PTO clutch pack or something? If that's the case, then plenty of brands will have similar losses.

As I said on another thread, would be nice the the guys over at Nebraska Tractor Test Laboratory could test pretty much all the tractors. There is a test there of a TYM T603, by the way.

K5lwq, a member here on TBN, did test his brand new Branson 4815R (12x12 Transmission) on a PTO dyno. Here is the thread about that: https://www.tractorbynet.com/forums/century-branson/421282-branson-4815c-pto-dynamometer-test.html

 

[EuroYanmar]

Good morning,

Of course, you can imagine that I don't have a test bench at home to measure those numbers.
They come directly from the importers specification datasheets that everybody can download from their websites.

I guess there are in US some imposed industry standards when measuring the power of an engine or the power available at a PTO. (which one ? SAE, DIN, ISO etc.....?).

My mistake was certainly to mix, in the chart, european models and US models as the industrial measuring standards may differ from one side of the atlantic to another BUT : european Branson F47 is US Branson 4815 and european TYM T475 is US TYM T474 etc...

It stays IMHO that the power loss computed FROM THE IMPORTERS DATA for TYM is huge.......

Really a Tym official would be welcome if he could clarify this point.

Phil

 

[RalphVa]

View attachment 677003

Good morning,

Yesterday I have made this excel sheet to have an idea of the power loss between engine and PTO.
I took the datas from official specifications. Some of these tractors are from european market and others from US market.
I hope I did no mistakes.

What do you think of this ?

Thanks for your help.

Phil

83-87% pump efficiency for most. Awful for Tym. They must be using a centrifugal pump vs. probably a gear type for the others; wonder if they have an overpressure bypass like typical of others; wouldn't need with a centrifugal. That loss goes as heat that has to be cooled off in the hydraulic cooler.

 

[EuroYanmar]

Gentlemen,

I have fresh data from a TYM technical document for TYM T393, the former european version of TYM T394 but without DPF.

Anyway, the numbers are interesting :

T393 gear : engine 38,3 HP PTO 30,1 HP power loss (38,3-30,1)/38,3=21,4 %
T393 hst : engine 38,3 HP PTO 28,6 HP power loss (38,3-28,6)/38,3=25,3 %

I don't say this, TYM wrote it !

So our bavarian friend from Manitoba was 100 % right !

Phil