engine R.P.M vs. P.T.O speed

terry274 · Post by **terry274** » Mon Aug 31, 2009 9:55 pm

At what engine RPM will 540 RPM be attained for the PTO? On the proofmeter, 1800 engine RPM is marked as "S.T.D PTO". This seems rather fast.
What would be the optimal speed for fuel economy and least engine wear?
Thanks,
Terry

JC · Post by JC » Tue Sep 01, 2009 6:38 am

Terry
I think that the PTO turns 760 rpm at 2200 engine rpm, so 1563 engine rpm= 540 PTO rpm. I have that info. written on a piece of paper, but I don't remember where I got it, so you may want to get a second opinion

Post by **Brian** » Tue Sep 01, 2009 8:12 am

1800 rpm is 540. That is the engine speed that is best for the engine when under load. It is between max hp and max torque and the engine should be run at around this speed when in work to get best fuel consumption, best wear charicteristics and long engine life.

Too low revs/light work =

Worn out engine.

Too many revs with no load/ engine not being worked =

Worn out engine.

Full load at 1800 revs =

Happy engine for many years.

We are lucky we do not collect John Deere tractors. The PTOspeed for 540 comes in at 2600 rpm. It used to be painful to set them up on fertilizer spreaders!

skipdow · Post by **skipdow** » Thu Sep 03, 2009 9:12 am

Are those numbers the same for petrol too?
My petrol Dexta seems to only have two positions for the revs.... on and off. The carburetor is pretty worn and I've never been able to find a replacement. It has no problems working hard tho.

dexta roadless · Post by **dexta roadless** » Sat Sep 05, 2009 1:51 pm

Hello Brian
It is correct on Dextas after aug. 1960 with a ratio of 3,33:1. Earlier models had a ratio at 2,89:1. That means rated speed of 536 rpm at pto with 1550 engine rpm. You can see what kind it is with the black knob at the hi/low lever. the old one don't have that.