[SEL] Question re tapered gib keys

[Germoamer at aol.com]

Jerry,
 
The tapered key will only work with a hub that has been machined with a  
taper in it.  Interchanging straight and tapered keys will not work at  all.  
If you insert a tapered key into a "straight key" hub it will only  bind up 
at a point to point contact, whereas if it is inserted in a "tapered  key" 
hub it will lock up the full surface of the key thus giving it maximum  
strength.  A tapered key in a straight key hub with the point to point  contact 
will work loose immediately.
 
It sounds to me that the key slot has worn oversize in either the shaft or  
hub or both.  If it is ok in the shaft and worn in the hub,  you can 
machine the hub to an oversize key and make a step key.  This is  something that 
is commonly done. The other thing that it could be is that  the bore size in 
hub has gotten slightly oversize during removal/running loose  and is not 
properly tightening up around the shaft.  In that case, the hub  has to be 
bored and bushed.  

Tom  Schmutz
Concord,  Va.
germoamer at AOL.com