T&T: Coupling shaft movement

[Lawrence Zeitlin]

On Sep 7, 2008, at 12:00 AM, Rich wrote:

> Clear of the slip, backing on both shafts revealed movement between  
> coupling
> and shaft with both backing out of the two-inch long coupling about a
> quarter inch.  Neither trying to tighten the set screws nor  
> shifting back to
> the old ones solved the issue.


Rich,

It sounds as if the shaft is scored right under the setscrews.  
Previous motion might have left a groove long enough to let the shaft  
back out a fraction of an inch.  There are two possible solutions.  
The best is to fit a set of split or clamp couplings. If you can't  
wait until they arrive, remove the setecrews, rotate the shaft in the  
coupling 90 degrees, then drill spotting holes just big enough for  
the points of the setscrews. They should fit exactly. This should  
secure the shaft using the shear strength of the setscrews rather  
than friction.

Larry Z