PTO hp and PTO ang vel (rpm)

[RyanMech1]

Hi, I posted this in agriculture but quickly realized that there hasn't been a post in two weeks. I thought it maybe better to seek help in this knowledgeable forum.

We're designing a tractor that will have a front mounted PTO and quick connect system and I am unclear on a couple of issues, any response would be greatly appreciated. I am trying to figure out what speed (rpm) the front PTO should run at, I understand that the standards for rear mounted PTO's are 540rpm or 1000rpm but have been told that a front mounted PTO may turn much faster (at engine speed). Also, does anyone know why the accepted values for rear PTO is 540 rpm or 1000 rpm? Secondly, I am wondering if there is an accepted value for comparing engine hp to PTO hp, I have found through research that PTO hp is approx 80-85% engine hp. If I know the design requirement of the power plant is 45 hp may I take that as the PTO hp for initial calculations or must I compensate for losses within the system? The only way I can see doing that is testing a similar power plant and obtaining the PTO hp experimentally. Thank you in advance for any information, Ryan.

 

[amorrison]

Slightly OT but this site may be useful to you.

New Zealand

http://www.bareco.com.au/files/pto2002/selgearbox.htm

 

[BillPSU]

I was involved in the manufacture of a PTO for a 400hp ag tractor. The gear box was rated to take the full hp through the PTO and was tested at full hp for 100 hours. PTO can be used for many different purposes including driving a water pump or some other high hp long duration purpose. Plan on using full hp and find out from your customers what shaft speed they need. If two different speeds are needed you may have to make RPM optional.
Watch your bearing lubrication which is what failed on our initial proto-type.

 

[JStephen]

It's possible those RPM's are engine speeds from way way back!

 

[Pressed]

.
1933 Harry Ferguson designed a final drive pto, which means a slow rpm. Continueing improvements there was a need to use high hydraulic pressure for powering implements. I assume there was a standard pressure at that time, 2000 to 2500 psi, not 100% sure. To achieve that pressure they had to use the the engine for power and the resultant rpm was 540. Around 1937 Ferguson had a hydraulic unit on an engine driven pto. There is direct reference to this in the links, but I could not find more about it.

I just visited a tractor meet/rally and they had a dynometer where every tractor was tested. Last year every same tractor was tested, just like the years before them. So, pto HP is going to change, up or down, otherwise those fellers would be sittin around comparing numbers from the last year.

Her are a few links I found, enjoy, I had fun finding them.

asae.frymulti.com/abstract.asp?aid=17742&t=2 (rpm spec)

http://www.fergusonsociety.co.uk/

(history, see 1937)

http://www.ytmag.com/articles/artint190.htm

(history)

http://www.iita.org/info/trn_mat/irg4/irg41.html

(history)

http://www.eh.net/encyclopedia/?article=white.tractors.history.us

http://www.gears-manufacturers.com/power-take-offs.html

(designed)

filebox.vt.edu/users/rgrisso/Grisso/Papers/031107.pdf

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/eng9927

ianrpubs.unl.edu/farmpower/g579.htm (testing)

http://www.hse.gov.uk/pubns/as24.pdf

(3/4 down, efficiency)

http://www.knowledgebank.irri.org/ppfm/farmPower/WebHelp/FarmPower_lesson07.htm

(efficiency)

http://www.calaged.org/ResourceFiles/Curriculum/advcluster/2853.txt

(efficiency)

http://www.pwrtst.com/brochures/agdyno.pdf

(dynometer)

http://www.valtra.com/com/commonfiles/press/articles/default_new.asp?CC=0&LANG=0&FROMCLUB=0&ID=54

(future)

_______________________________________
Feeling frisky.........

http://www.tailofthedragon.com

 

[Philrock]

Many engines are not designed to deliver full power from the front end. It would be wise to check with the engine manufacturer regarding this.

 

[CSLufkin]

How they started out at 540 and 1000 RPM is probably another long discussion but for whatever reason they did. My point is that I think the standard has been set and thousands of standard implements and gearboxs have been built to work properly at these RPM's. If you want your front mounted PTO to use standard existing implements, it should probably stick to the standard that has been established. Now don't get me wrong, I am not against re-inventing the wheel if it is for an improvement, but you will have to accomodate all the old stuff that is out there or else consumers will say "why should I buy all new implements just to match your new fangled PTO setup?". Remember, even if you design this to run specific attachments that match up with it, the consumer may well decide he wants to run one of his ols implements/pumps off the thing in the future and he won't be happy if it won't work.

Just my $.02