PTO Unit - Need to Call in The Experts!

[CatBuilder]

I have settled on propulsion for my boat, after having looked through electric, outboards and diesels.

The lightest weight, most reliable setup I could find is a pair of Yanmar 3YM30's. After remembering how many times I've had to pull carbs on gasoline generators and outboards to clean them because of the junk they call gasoline (petrol) in the States, I am not going with outboards.

Electric, no matter which way I do it, weighs more than Yanmar engines.

That leaves a pair of 3YM30's.

Now, I also need that tremendous electrical power for my guests, but I don't want another 300lbs+ engine involved in a stand along marine geneset. So, I'd like to hook a generator head/end up to one of my Yanmar drive motors instead, for intermittent use when not motoring.

Who has ideas on how this would be done? Anyone understand PTOs in this application?

So far, my options seem to be:

1. Be abe to disengage the prop shaft somewhre along its length and attach a notched belt pulley system to the standard shaft, between the transmission and the rest of the shaft.
2. Find some kind of geared PTO for the flywheel that sits on it like a starter motor does and run the generator head from this. Does such a thing exist?
3. Use some kind of T shaped planetary gear box that allows you to switch between a pair of output shafts. One for the prop shaft, the other for the generator head/end.
4. Somehow attach a notched belt drive between the flywheel and the transmission, so I can just put it in neutral and enjoy the spinning flywheel power to spin the generator end/head. I'd probably need a clutch on that notched belt so I could turn off the generator spin when using the transmission in gear and/or regular prop shaft. Do they make clutched pulleys that attach to the flywheel, but sit between the flywheel and the transmission?

How would you do this hookup?

What's the best way?

[thudpucker]

"Tremendous Electrical power...." would be a XXX Watt Generator.

If you have room????
put the Generator in between the Front of the Yanmar's.
Use a Belt drive and Clutch from the Yanmars to the Generator.
That way, you can engage either Yanmar.
That's just the first thing that popped into my head. I have never seen or heard of such a thing.

[CatBuilder]

Sorry, Thud. I did leave out some details. It's a 10kw 2 pole head (for lightest weight). The engines are in different hulls, so I can only hook to one of them. What is that belt drive and clutch? Where does it attach?

[PAR]

V belt it to an electric clutch. When you need the generator, the clutch engages and you're up and running, other wise the clutch free wheels and there's next to no load on the engine.

[CatBuilder]

Thanks, Par. Where does the v belt attach to the engine? That's the missing piece of the puzzle. How do I get a pto going? Prop shaft? Flywheel? What piece of hardware can I use at the Flywheel or shaft? What bearing setup can handle the load?

[thudpucker]

You'd probably put the Alt. drive on the front of the Engine.
Several ways of doing that.
Sometimes you bolt an extra Pully on the front of the Crankshaft to run to the Electric clutch.

If the Alt turns the same way, mount it alongside, if it's the opposite way, mount the alt facing the engine.
Electric Clutch is similar to the A.C. clutch on your Automobile.

[Frosty]

This is nothing new and is normally used on much bigger engines, its called a cruising generator. (PTO) power take off the front crank pulley is criticall I think your way over. Yanmar gives information on this.

10 KW is huge for 28HP motor,I dont think it could handle it if you loaded it.

The best way to connect is a hand throw mechanical dog clutch, select at stop then start,--when Volatage is acceptable then you connect exite. An electrical car AC type would not take this torque for a second.

3KW would be ample, what on earth do you need 10 KW for.

These simple gens do not have AVR and voltage is set by RPM and hopfully the governor will keep it set at your 240V and 50/60 cycles . Your little 28 will struggle with keeping a usable stable voltage.

I dont know the maths but 28Hp is not enough for 10KW.

[PAR]

It takes about 18 HP to drive a 10k head, this is a hell of a load for a 28 HP engine, that's also used as propulsion.

Electric clutches can be had to tolerate this level of input, as can a manual dog clutch.

The head is front of the engine mounted (very probably considerably off to one side, because of size) and if reversed rotation from the engine, it doesn't have to be mounted backwards, you just need an idler and tension serpentine pulley arrangement.

An electric clutch can be setup to kick in automatically, once operating RPM and/or voltage is reached.

I'd have to agree that 10k is a huge requirement for a yacht, unless you're running a separate A/C system. Have you counted up the wattage you'll need?

[Frosty]

I have a 3kw diesel industrial, removed from its frame and glased in on mountings in the front of my cat. I remeber carrying it down there with one hand The fuel is connected to the ships supplywith a ticker pump and control was wired back to the helm . It Is air cooled in a air box made of sound absobing compound the temp guage never goes over 200. Its been in there for 7 years.

I run the air con if I want but in the galley deversification is required, I dont use the toaster and the kettle and the micro wavce and the rice cooker , but with a bit of for thought and management it perfectly usable.

All ships supplies on a small boat has to have diversification applied to the loads possible.

This system cost me the price of an industrial Yanmar 3 KW. No water cooling no pumps, electric remote start, ---which I cant hear, I turn the key and see the volt guage jump up.

I could replace it 3 times for the price of a small marine gen.

Your 10KW is too big and will possible snap your crankshaft.

I have a yanmar book of ALL yanmars Ille try to look up max PTO load when I get time but I would be very very reluctant to put 10KW on the end of one of my 250HP yanmars.

And only a 2 pole as well!!!!!--A 4 pole wouild be less harmonic vibration.

[thudpucker]

I don't know all that math either.
We built Cabins with 2500 KW Onan's.
Two or three Skill saws, lights and an Air compressor running almost 18 hours.
I'm no help to you there, just relating an experience.

[philSweet]

Thud, that'd git-r-done alright.

a Cat, not an Onan. 3516

[TeddyDiver]

I'd propably use something like here http://www.loganclutch.com/industrialClutches look at P series. Or a gearbox with PTO, but dunno if there's one in this size. Better ask Yanmar me thinks..

[Frosty]

The clutch alone will cost more than my little throw away genies.

[waikikin]

If considering large belt driven loads on the front of the engine, extra bearing support is required.

[waikikin]

Some "yanmah" http://www.yanmarhelp.com/i_pto.htm