Cooling the shaft does work. The mechanics, at the utility where I
worked, sometimes wrapped the shaft with dry ice to cool it. A simpler
approach is to follow the coupling and bearing manufacturer's
recomendations. Instead of the 1 to 2 thousanths of shrink per inch of
shaft that mechanics seem to hold sacred, machine it for 1/2 thousanths
shrink per inch of shaft with a minimum of 1/2 thousanth as per mfg.
recomendations. They also recommend that the coupling, bearing or
whatever be heated in an oil bath to 300 to 350 deg F. It's a lot
better for the metal than a torch or the shock of a superhot coupling
suddenly being slamed onto a shaft that has been frozen with dry ice.
With the smaller shrink fit this heating is more than enough to let it
slide on easily. It comes off more easily too. I switched to that
approach and never had any problems. Warning: Following mfg.
recomendation could lead to more serious illnesses like reading
instruction manuals.

Ken