PTO speed for lo and hi

I take it you have a two pole alternator that requires 3,600 r/m to get 60Hz.

Your speed selector lever needs to be in the rear position for (corrected) 720 r/m and forward for 540 r/m.

FYI: 8kW only needs about 11 HP to produce so that would be the demand, even on a 125 HP engine. Doubt there would be much difference in fuel consumption per kW/hr between the two.

The FarmPro brochure says your PTO is 540/720 r/m, so maybe you can't get 60Hz after all. The 1,000 r/m PTO shafts will have 21 splines. Curious, let us know.

i am guessing that the 125HP motor would have a larger displacement so at a given RPM the fuel consumption would be greater.

My Jinma 284 has the digital dash with no battery volt amount just a light, and Fuel / temp then RPM analog gages. It does not show where the rpm's need to be for 540 or 1000 rpm PTO.

I am also looking for a TPH generator after this past weeks storm in NE. Ran old 4000 watt generator to run furnace, but would like to run well and lights maybe also.

Hopefully someone knows correct RPM to run PTO.

Thanks

Mike 

You run the PTO at whatever RPM that particular implement calls for.  Each implement has its own gearbox designed to run the thing at the proper final speed based on a given input rpm and you should follow it.

With a small PTO generator like the 15KW unit that Harbor Freight sells (or used to), they call for 540 RPM PTO speed since that is the common one.  Generally speaking, if you have an implement that takes a six-spline PTO shaft it is designed to run at 540 rpm.  Better generators have both voltmeters and frequency meters on them so you just set the throttle to yield 120 volts at 60 HZ with the load you're putting on the generator.

If you need to know what engine RPM yields a given PTO speed, you can get inexpensive shaft tachometers, either optical or mechanical, from HF and other suppliers for about twenty bucks.

Well, my bad. The 540 r/m position is toward the REAR, and the 720 r/m is to the front.

My apologies.

I just recently dove into PTO generators for the same reason. We lost power for a couple days after Irene blew through and I discovered that my 5000W Coleman generator couldn't start my well pump. It handled 2 refrigerators, a TV, a bunch of lights, and a couple PCs. I believe it could handle running my 1.5HP well pump, but it can't handle the startup current. So I looked at Harbor Freight 15KW and Northern Tool 12KW generators for $1500 each. I was going to go HF because it included the PTO shaft and 3PH frame, but they were backordered for about 6 weeks, so I bought the Northern Tool unit, built my own frame, and borrowed the PTO shaft from another implement. The generator expects 540RPM. I have a 2008 NT284 and the meter on the generator was right were it wanted to be at 2000RPM on the engine.

Grumpy wrote:

“The generator expects 540RPM. I have a 2008 NT284 and the meter on the generator was right were it wanted to be at 2000RPM on the engine.”

Excellent. The transmission in the alternator's PTO increases the rotor speed to 900 r/m if it's an eight pole, or 1,200 r/m if a six pole, 1,800 r/m for a four pole, and 3,600 r/m for a two pole – to get 60 Hz. (alternator trivia).

The generator claims to have a 1:7 gearbox. 540 x 7 = 3780. Would it be safe to assume then that the generator is a 2 pole, and that 2000RPM on the engine is actually 514RPM at the PTO in order to yield 3600 at the alternator? This is of course assuming that the meter on the generator is acurate.

  I learned a few things from testing. I learned that the NT254, Jinma 284, with what I think is the Y385T engine, has the guts at 2000RPM to produce at least 11000 watts from the Northern Electric 12KW generator. I have a slight issue though, and I am not sure if it is that the governor on the engine is not 'tight' enough to hold the RPMs under heavy load, there is an inefficiency in the generator that requires boosting RPMs to compensate when under heavy load, or I am dropping significant voltage in the wiring between the generator and the well pump when the pump kicks in. With about a 4000W load on the generator and the engine at about 2000RPM the generator outputs 240V. Then my well pump tries to start up, adding what appears to be about another 7000W load. The engine slows to about 1960 RPM, the generator output drops to about 234V and the pump gives up and kicks off. That seems ofuly oversensitive! If I am ready and watching I can bump the throttle back up to compensate, the geneartor will handle the load, and the pump is happy. However, if I leave the throttle there when the heavy load goes away the engine jumps up to about 2040 and the generator output to 245V. Anyone have any ideas? Sould I worry about running the house at 245V so the tractor and generator can handle the well pump??

Chuck:

“but I felt the MF1135 (Masssey Ferguson tractor) was using to

much fuel to produce 4000-6000w I needed.”

Do you know this for a fact? 1 kW of power requires 1.34 HP to produce, 1 HP = 42.44 BTU/min., 1 BTU = 0.0003930148 HP-hr. So what you actually need to determine your anticipated fuel consumption is to know what your engine's BSFC (Brake Specific Fuel Consumption) rate is.

Diesel fuel averages 18,550 BTU/lb. Did you actually run a GPH comparison with a fixed load?

Grumpy:

It sounds like the governor may be “sticking” – Slow on droop response and overrunning. If I understand correctly, your generator handles a 4 kW load @ 240V just fine, but when a starting spike of an additional 7 kW is applied you drop voltage to 234V (acceptable), but then the well pump trips (probably from under voltage protection), but then voltage increases to 245V (also acceptable for a second or two, and the cycles will fluctuate accordingly). Unfortunately, these are not isochronous governors so you are limited to what you can do with them. Do you have any idea what the voltage drop is in your wiring? Wire size? Length of run, etc? What is the HP of your well pump motor?

I was going to buy a PTO generator and had decided on the 12kw Voltmaster from Electric Generator Direct. The reason I selected this generator was the voltage regulation that the newer generators have and are safe for sensitive electronic equipment. The Harbor Freight Tool PTO generator does not have voltage regulation. Now I needed a three point platform and ended up ordering the parts from Harbor. After five weeks I was told to wait a little longer. I am still waiting!!

Ended up buying a 7kw generator from COSTCO online that was safe for sensitive electronic equipment using a $200 off coupon. I think I ended up paying $700 for the generator. I believe these generators are imported by Eastern Tool.

Short story, you can buy a lot of gas with the savings by buying a portable gas generator over a PTO generator. Now, if you need 12kw, that is a different story.

Speaking of 12 kW. This is my Onan DJC Just fired up after sitting outside (covered)for four years. 240V, 50A, 1Ø, 1,800 r/m, air cooled. This will power my shop until I get the electrical run.

That should handle you air compressor! How do you plan to heat you shop?

Pellet stove.