Hi All
The instructions that accompanied mine when I bought said that the correct usage was, that once the extractor was tightened up, you should hit it with a hammer and then tighten up again by one quarter of a turn, and then again use the hammer. This cycle should be repeated until the clutch centre is free. As has been said do not attempt to use it as a puller the threads will strip if you use the tool in this way.
The end of the "extractor" bolt is pointed hammering this into the end of the gearbox shaft is a none too clever idea
I have come across split mainshafts because of this
A few weeks ago I was brought a T140 bottom end where the owner had broken two pullers trying to remove the mainshaft pinion (plain shaft and keyway)
The PO had tried heat as well
The end of the crank was mushroomed and blued from the abuse
A better idea is to make a thick copper or brass pad that will sit in/on the end of the shaft so the pointy bolt will seat against that instead of the steel shaft
I have also seen the right hand end of the gearbox suffer from hammering the puller
It can break out the alloy around the RH bearing retaining circlip or dent the bearing races
Tension up the puller and pour a kettle of boiling water over the clutch shaft adaptor the "sudden" heat works better than applying a blow lamp that gives time for the heat to travel through to the main shaft as well
With decent quality pullers ( the ones that are black in colour usually have been heat treated)
an air or electric impact driver on the puller nut works well
John