I emailed Rexnord rep to see if he had any fluid coupling ideas for me...guess not...

Begin forwarded message:

From: Brian Clark <Brian.Clark@rexnord.com
Date: August 24, 2011 2:14:57 PM CDT
To: gene kahn
Subject: RE: question about fluid coupling

Gene, spoke with some engineers about your application, the HP is no problem, but
the max speed for a fluid coupling is 1800 rpm.
If you are looking for soft/start flexibility you might want to
look at a inverter for the motor.
Thanks
Brian Clark

-----Original Message-----
From: gene kahn
Sent: Sunday, August 21, 2011 4:46 PM
To: Brian Clark
Subject: question about fluid coupling

Brian,

I am investigating the use of fluid couplings for applications
of up to 600 HP, at 6-8 thousand rpm.  The diameter could
be up to 14 inches or so, and the length [the thinner the
better] could be up to 6 to 8 inches.  Do you have anything
like that?  Thanks.

Gene Kahn