I have been catching up with the digest E mails since I have been on
vacation and would like to comment on removing the rear hubs
On the Spitfire and Stag the standard advice is not to attempt pulling the
hub off unless you have the Churchill puller as it is possible to bend the
hub flange. There was a comment recently on the Stag list about getting
around this problem with a simple tool. When you think about this operation
it's not a good idea to try to break the friction fit of the Morse taper by
the use of a hub puller, Churchill or other , to slowly build up a force
that is big enough to overcome the friction since this requires a huge
force. It can be done of course with the Churchill puller since this has a
strong flange that does not put a bending moment on the hub flange as
simple puller drawers do. The friction fit is best released by applying a
sharp impact to the shaft itself. This was the point made in the Stag E
mail I read. The question was how to do this. If I understood the Stag E
mail correctly it seems that the outer diameter of the threaded portion of
the shaft ( where the big nut screws on) is smaller than the outer end of
the Morse taper so that there is a bit of land on the shaft where the
shaft diameter steps up to the size of the Morse taper just after the end
of the threaded section. If one could apply a sharp blow to this land with
the hub supported in a vise then the force needed to break the friction fit
would be much less than that required if one used a steadily increasing
force applied by the Churchill tool. This was the solution proposed in the
E mail and the writer had used it with no problem. I didn't really fully
understand just what the person did but it seems that he had fabricated a
small piece of tube which had an inner diameter that just cleared the
thread diameter and the outer tube diameter was the same as the Morse
taper. He then screwed a nut on the shaft so it just lightly touched the
end of the tube and given the nut a sharp blow to break the friction. I
guess that if you use a nut which is a little loose on the threads you will
not distort the threads as you strike it. I have never studied a Spitfire
shaft, or a Stag for that matter, to confirm the presence of this land but
I certainly the engineering premise behind this technique is sound. Did
anyone else see this and could comment?
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