Fastening pulleys onto shafts.

[Scraperman]

I have a query regarding the fastening of pulleys onto their respective shafts on a T gearbox made by Superior. I am quite conversant with fastening pulleys onto shafts by gib headed, parallel and woodruff keys but this is a method that I have not encountered before. Briefly the pulley is placed over the shaft. The internal diameter is much larger than the shaft and so it just sits there when the boss, which has a tapered external surface, an internal keyway, and a slot, the latter allows the surface that mates with the internal surface of the pulley to expand or constrict. The pulley is placed over the boss and the 2 bolts are screwed through the flange of the boss and into the threaded holes in the pulley.


At this stage the pulley has to be lined up with whatever other pulleys are involved in the drive train so that the vee-belt is running true otherwise it will wear out quicker than if it is set up correctly.




The 2 bolts that can be seen in the boss are used to pull the pulley over the boss and because the boss surface is tapered the tighter it is pulled over the boss the tighter it becomes and the boss also becomes tighter on the shaft because the internal diameter has been decreased by the tightening procedure. But here's the problem. The pulley has been lined up with other pulleys but the tightening process moves the pulley along the shaft so it becomes mis-aligned with the other pulley(s) in the drive train. And when is the parallel key inserted before the tightening process or is it hammered home when all the tightening has been done ?

 

[StarTech]

keys are installed before tightening. And tap the fitting down as much as you can while keeping the pulley(s) aligned before tightening the screws the final amount. And you don't have to fully seat the fitting either. At least that how I do it on Scag Turf Tiger spindle pulleys here.

 

[Scraperman]

keys are installed before tightening. And tap the fitting down as much as you can while keeping the pulley(s) aligned before tightening the screws the final amount. And you don't have to fully seat the fitting either. At least that how I do it on Scag Turf Tiger spindle pulleys here.

Thank you for that. When you wrote "tap the fitting down as much as youcan" did you mean to tap the boss into the pulley as much as I can ? I have actually got the box off the mower at the moment but I have to put it all back together and then put the pulleys on. I had hoped that I could put the pulleys on first and then put the top of the box onto the bottom but that's not possible.