PTO Generator Output

I have ran a 30 Kw PTO gen set off of an International Super H (around 36 HP) up to about 17 Kw before the engine topped out.

I am not sure of the power losses through your PTO, and I am not sure of the particular Hp rating system on your tractor. However, if the tractor is rated for a nominal output of 34 hp, then this equates to about 25 kW (1 horsepower is about 746 Watts- actually, 745.70). If the tractor is old, or the output power is some wierd unit like "brake horsepower", then you may not get 25 KW out of it. Unless you have a proper governor on the tractor, you will need to set the rpm for whatever load you are drawing from the generator. Just because it is a 25 kW generator does not mean it is putting out 25 kW. If all you are driving is the 7.5 hp pump, then all the tractor has to produce is about 5.6 kW plus whatever losses in the drive train. It is the electrical load you put on the system that determines how much power you take out of the system...

Hi wfga,

You should not think of taking more than 50% of the rated power out via the PTO, as a rule of thumb. Things to consider when arriving at the connected load are:

1) What the characteristics of that load are, is it continuous or intermittent

2) What type of starter is being used. VSDs are kinder to limited power sources than DOL, but you are not going to fork-out big money on one of these I reckon.

Given that you have mentioned a submersible pump this will present a fairly steady load but with little respite for the engine.

Think about the working environment for the tractor as it may over heat if subjected to a continuous demand if not placed somewhere the air can circulate freely around it.

If the tractor is to be left unattended for long periods, say several hours at a time. You may want to invest in an over temperature water stat for the radiator and a interface trip relay for the oil pressure switch. Wired in series and connected to a solenoid valve in the fuel line these will afford you the necessary protection to avoid cooking or seizing the engine. I know this having done the latter with a Fordson Major which had its PTO coupled to an irrigation pump; left unattended it 'expired' with wrecked bearings and bores!

Happy pumping,

Massey.