The elusive PS (Pferdestarke)

gbirky · Nov 17, 2003

Not that it really adds much to the final evaluation, but I got curious enough about the units used to rate power on these Japanese tractors to search the internet. They are all rated in PS which is pferdestarke (or literally power of a horse). I found it at this web site.

It is actually very close to our horsepower. Now the question remains as to whether this is engine power, drawbar power, or pto power.

DavesTractor · Nov 17, 2003

Greg,

Now you've started something! I researched that once as well and it seems to be a PS equals a HP...but what HP; gross engine, net engine, 1 hour rated, 12 hour rated, PTO, drawbar?

There are a few direct engine cross overs from Yanmar Japan to Yanmar USA. Looking at the specs, it appears adding 20% (multiply by 1.2) to the PS ratings on the gray Yanmars will give you the rating we would have seen in the US. I think a YM240 and a YM2000 are almost twins, as are the YM155 and YM1300. The math works on these and others.

Some say a PS is a kw, and that simply is wishful thinking.

nuvz · Nov 18, 2003

So if a 2010D has 23 hp, would that mean that it is really 27.6?? Please help me here!! Thanks!
/forums/images/graemlins/confused.gif

DavesTractor · Nov 18, 2003

A 2010 would be 20 x 1.2 = 24HP at the engine. I think that is a reasonable approximation...but not science. Where did you get the 23HP number?

nuvz · Nov 22, 2003

I downloaded a list off one of the old Yahoo group sites and have kept it current by adding new stuff as it comes along. It is fun to refer to from time to time as you read through the posts on this site. I have posted it before, but here it is again in case you missed it. I can only post it as a text file, but you should be able to upload it into a database or spreadheet if you wish.

nuvz · Nov 23, 2003

I see that the list I posted left out the weight info... I added it since that is a REALLY relevant item! /forums/images/graemlins/blush.gif /forums/images/graemlins/cool.gif

TexasTractors · Nov 23, 2003

Here is some history on PS, and the calculation. The PS HP marked on the Yanmar engines actually calculates out to be less BHP than is usually advertised.

One measure to be aware of though is the "continental horsepower" or PS. This stands for "PferdeStarke" - the German translation of "horse power". In France you sometimes see the same measure being called a "CV" for Cheval Vapeur. This measure was chosen in Europe as being the closest thing to a horsepower that could be expressed in nice round metric units - 75 kilogramme metres per second to be exact. It is commonly used by car manufacturers nowadays and tends to get used synonymously with bhp although it is actually a slightly smaller unit of power. One PS is about 98.6% of one bhp. The conversion table below covers the units most commonly used to express power and torque.

To convert from BHP to PS multiply BHP by 1.01387
To convert from PS to BHP multiply PS by 98.6