In article ,
says...
I had the chance to get a used (very used) surface grinder and I took it.
I've never used one before so I read some of the previous threads but still
have some questions.

First, if anyone has a manual I'm willing to pay for a copy.

Main problem is this: If I hold spindle at the threads, I can rotate it
about 30 degrees before it catches the motor shaft. I can twist it back
and forth and feel it bang as it engages with the shaft. I assume there's a
key in there but I don't know how to remove the spindle from the shaft. (I
hope I'm using the right names for these parts).


It sounds as though there may be a jaw type (AKA Lovejoy)
coupling in between the motor and spindle, and the spider
is gone.

http://www.lovejoy-inc.com/contents.htm

Ned Simmons