In message ,
George writes
Evening all.

In my workshop I have a Lister 4 cylinder diesel, air cooled 3 phase
Alternator I think it must only have two poles as to get 50 Hz it seems
to run far too fast and makes far too much noise in so doing.

It is at least twice as powerful as I would ever need and I often use
it at about half revs at which speed it still generates enough to run
an old Milling machine, However It would be very nice it I could run
the diesel at this low speed and still get 50 c/s and the correct
voltages. It is skid mounted, bolted to the floor on a heavy chassis
but the engine and alt. are close coupled. I was toying with the idea
of separating them and hooking up a chain shaft drive behind the set to
gear the motor speed down by at least half.

This will be a big job I fear, as they are very close together and it
might be necessary to move the engine to the right a bit to enable
sprockets or even pulleys to be connected to gear down the alternator.
Has anyone ever done this and has anyone any simpler lateral solution.

Or - alternately does anyone wish to swap a noisy 40 Kw set for a nice
quiet 15- 20 Kw set ?

No help to you George but I am reminded of an ingenious set up used to
provide a range of speeds on a flat belt drive centre lathe.......a car
gearbox, directly driven from the motor, with a flat drive pulley
instead of the prop shaft drive:-)

Not used in a production environment of course!

--
Tim Lamb