That sounds like the system used on aircraft (except for the reliability).
At ten grand or more per propeller, I doubt it's what he's looking for.

Roger

http://home.earthlink.net/~derbyrm

"Steve" wrote in message
...
snip
The prop is has a hub with hydraulic mechanisms that rotate the
synchronized multiple blades from either side of "0" pitch (neutral) to
fwd or reverse.

The hydraulic control of this blade assembly comes through an Oil
Distribution Box (OD Box) on the extreme inboard end of the prop shaft.
The shaft end rotates inside this box and the hydraulic oil pressure is
transmitted down two passages bored from this inboard end, down to the hub
end where it is can act on the prop blade mechanism to rotate the blade.

This may sound overly complex but it eliminates the need to stop and
reverse the engines while maneuvering. Much less complex than reversing
gears for engines of these HPs.

The one problem I encountered while dealing with these system was from
total loss of hydraulic pressure. The prop blades seem to have a mind of
their own and as long as the engine is running/engaged the prop continues
to rotate and may switch from "0" pitch to full astern (my experience) or
full ahead.


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions