Re: Cub Genset

Fri Nov 02, 2012 9:18 pm

Scrivet wrote:Not a generator expert but won't the size of the electrical load applied have an effect on the engine speed thus the generators output? Will the Cub's governor be up to the task of keeping the engine speed constant under varying electrical loads?
The Cub's governor should be capable of keeping the engine rpms constant/close enough. Actually the Cub engine may not even notice the additional load on the generator head.

Example provided in opening of this topic. 3500 Watts, 6 hp engine required. These figures are the maximum.

Some figures from a numbered cub low-boy engine: 1200 rpms = 8.87 hp. 1400 rpms = 10.5 hp. Basically using 1200 rpms and 8.75 hp, the Cub engine could easily handle the 3500 watt generator head requiring 6 hp. And there are still engine rpms available to the governor.

Re: Cub Genset

Fri Nov 02, 2012 9:31 pm

Eugene:

Could a C-60 Power Unit handle say a 10kw or 12kw generator head?

Re: Cub Genset

Fri Nov 02, 2012 10:36 pm

Ok, so my earlier attempt at a post got lost in the x button....

In almost all cases, a gen-set engine uses a zero droop governor. The cub governor is a 150-200 rpm droop. One could possibly modify it to reduce the governor droop, but in non-critical applications, one would probably be OK. You would not want to power anything that needs clean power - anything computer that is not on the opposite side of a transformer.
Perfect speeds for our power needs are 3600 (single pole) 1800 (double pole) and 1200 (3 pole). Since 1800 is really close to FLGS on the cub, whatever you do should strive to run the cub right at FLGS(full load governed speed). You also want at least 10% reserve power, so for a cub that would limit the generator head to about 9 hp, or about 7 KW. A 5 to 6 KW generator head should be a near perfect fit.

For the northern tool gen heads, you would need to run a 1:2 overdrive ratio, or maybe slightly under 1:2 depending on what year cub you have (1600 FLGS or 1800 FLGS). Would be a nice addition to the cub toolbox.

Re: Cub Genset

Fri Nov 02, 2012 11:04 pm

Dan Robertson's solution.

Image
Photo by Dan Robertson

Re: Cub Genset

Fri Nov 02, 2012 11:29 pm

I guess then when the B&S/knock-off engine blows up I can take the 6.5kw head off of that and power it with my C-60. It is something I have been thinking about for a long time as a permanent generator solution for when power goes out. But I do want to run my puters -- so surge bars ain't going too far. Oh the house is getting a surge protector at the main panel.

Re: Cub Genset

Sun Nov 04, 2012 9:55 pm

Dan did good.

I'm not an EE, but rather an ME. A surge protector won't do much good against the type of problems you'll have if your power is not clean.

You want as constant a speed as possible to make sure the AC frequency is consistent. That's why 2:1 overdrive and 1800 rpm input with a single pole generator is so important. It would depend on the voltage control strategy used in the generator, but it should remain constant throughout the rated speed range of the generator. You can also use a larger generator if you so choose, but you just need to be careful not to overload the engine. You could hook up a 10KW generator, just don't put 10 KW of load on it....the cub will end up on its knees.

Interesting idea - maybe the cub becomes the backup power supply for the house, but I still need to wire the transfer panel....

Re: Cub Genset

Sun Nov 04, 2012 10:52 pm

I have been thinking about this a long time and have always wanted to see if a C-60 Power Unit could fit the bill. Roger is putting in the Generator Panel with 16 circuits and the lock-out switch to prevent feedback. Will probably need some gauges for the output and of course rpms etc., to provide the constant speed. But I am hoping that this might be my eventual setup. The surge protector is for NB Power and not the genny. That was just an aside. Decided it was time to get with the program on that.

Re: Cub Genset

Mon Nov 05, 2012 7:29 am

I would think the cub would handle the job better than any other small engines. Most of the hp ratings given for the gen heads are for single cylinder engines. I would think that the cub being a 4 cylinder, still producing around 10hp, that the torque from the 4cyl would be ample amount to compensate for most any given load. The speed on the head unit can be brought into specs by different sized pulleys and still leave room for the governor to work safely. The picture of Dans generator is exactly what I would like to do, a good fast hitch setup would be so quick to get ready and yet it still doesn't take up much storage space.

Re: Cub Genset

Mon Nov 05, 2012 9:55 am

Rudi wrote:I have been thinking about this a long time and have always wanted to see if a C-60 Power Unit could fit the bill. Roger is putting in the Generator Panel with 16 circuits and the lock-out switch to prevent feedback. Will probably need some gauges for the output and of course rpms etc., to provide the constant speed. But I am hoping that this might be my eventual setup. The surge protector is for NB Power and not the genny. That was just an aside. Decided it was time to get with the program on that.



Basically 2 hp per KW, so 6.5 KW needs 13 hp. 1 cyl or 4 cyl, 1 foot-pound of torque or 1000 foot-pound torque, does not matter. Horsepower can compensate for a lack of torque but torque can never compensate for a lack of horsepower. Your cub could run the gen headset but not to full power. Another consideration is some gen heads have only one bearing and depend on the engine itself to provide the other bearing.

Re: Cub Genset

Mon Nov 05, 2012 10:52 am

Rudi wrote:I guess then when the B&S/knock-off engine blows up I can take the 6.5kw head off of that and power it with my C-60. .........
If/when that happens you may have to do some engineering. Most of the generators that mount directly to a small engine do not have a bearing on the drive end, or if they do it is a bushing, not designed for side pressure for a belt.