In article ,
Jon Elson wrote:

Ignoramus26468 wrote:

Have you considered using a system of pulleys?

The pulley on the generator head side could be attached to a separate
shaft, which would be connected to the head's shaft with a U-joint.


Pulleys? For a 25 KW alternator? That could be pretty big! The alternator
may not like that much side force on the shaft, either.



Another idea I'm thinking about is having a plate machined that would
bolt to the flywheel and have a 1.5 inch shaft coming off of it that I
could couple to the generator head with a heavy duty rubber insert
type coupler. (I'm concerned that this setup would be hard for me to
balance, and the stresses on the shaft welded to the plate be to high)


Many alternators and generators designed for IC engine drive have a "quill"
inside a hollow shaft. This is essentially a torsion spring that allows
the engine
to vary in speed due to the power strokes without massive torque pulses
between
the engine and alternator. If this alternator is so equipped, the quill
also serves
as a coupling, and will take quite a bit of misalignment. They often have a
rubber damper (looks like a tiny clutch) to absorb any resonance in the
quill.

This would work if you can run the motor continuously at the desired
RPM, is it 3,600 or 1,800 for those ST heads?


Yeah, if its a 3600 RPM alternator. you REALLY don't want to have the
car engine wailing away at 3600 RPM all the time.

In general, that would indeed be true. But what says you've gotta have
the beast mounted directly to the engine? Especially if you've got the
tranny sitting right there to go with it.

Overall, if I were as worried about the side-loads and alignment as the
OP seems to be, I'd take the beast and mount it with a doubled pulley
system - triple-belt from tailshaft of tranny, belted onto half of a
6-position pulley on the alternator head, then a triple-belt from the
alternator to an idler pulley positioned and tensioned to balance the
side-force from the tranny pulley. Presto. You're balanced and aligned
as good as you're ever likely to get.

Select appropriate gear to give a comfy 3600 on the tailshaft of the
tranny, and you run 1:1 pulleys. Dunno about the OP's engine, but if I
were to do that with my spare Mazda engine/tranny set, I'd probably have
it in third gear with the engine turning right around 27-2800, which is
dead in the sweet spot for this little 4-popper/5-speed combo. I'd have
to do the math again to figure out exactly where to pin the engine for a
dead-on 3600 at the tranny output, but that's trivia. It should be
putting out just short of 75 ponies in that configuration. Ought to
power a REAL healthy genset... How many watts is 75 horsepower again?

I could go with being able to say "Rolling blackout? What's that?"

Hmmm... Y'all've given me an inspiration... I'll keep you posted on
what, if anything, develops.

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