Locating ring location 2

[cokeguy]

For a belt driven centrifugal fan, with the shaft supported by a pair of spherical-roller bearings with their respective SAF-type housing, where should the locating ring be installed to fix one of the bearings, in the impeller side bearing housing or the pulley side housing? Thanks.

 

[Tmoose]

I fix the bearing with the near the component that can least handle the axial misalignment caused by thermal growth .

On a hot fan I'd lock the fan bearing to avoid stuffing the fan into the shroud. Then Axial shaft growth would tend to mis-align the belts, which I don't consider a real big deal.

What I do worry about is asking a heavily loaded bearing to slide in a housing. If the fan/blower wheel is real fat, and the belt pull is not close to vertical, then the opposite bearing wants to fly upward. In that case I would probably lock the fan bearing, because it won't want to slide very much.

 

[cokeguy]

OK, thanks. Another question I´ve had regarding pillow block installation in these cases is the orientation of the lock nut for the bearing´s adapter sleeve. Any guidelines regarding whether the lock nuts should point towards the fan or towards the pulley, or point against each other? Or it simply doesn´t make a difference in which side they´re installed? Thanks again.

 

[JJPellin]

If you have access to an original manual and drawings for the fan, it should specify on the General Arrangement drawing which bearing should be fixed and which should be floating. For a fan that is between bearings, it is obvious to fix the drive end bearing. For an overhung, it depends on the temperature and configuration. The last fan of this type that I worked on had the fan-side bearing fixed. This fan was driven directly from a motor with a shim-pack coupling that could take a bit of change in coupling spacing without a problem. I did not find a drawing that would show which way to orient the bearings taper sleeve and nut. I usually put them both in the same direction with the nuts away from the fan. But this is really more for ease of assembly than any real mechanical need. As long as the floating and fixed bearings end up in the right place, I don't think it matters.