Tapered bearings vs pillow blocks | |
The reason is axial thrust. As hard as the machine is pushing whatever is attached to the axis, the axis is pushing back against the lead screw. The tapered bearings are designed to eliminate any resulting axial motion in one direction. So to get stiffness in both directions two bearings are used back to back and facing in opposite directions.
You could use a pillow block, but it defeats the purpose of using a precision ground screw and ball nuts if the whole assembly has any play. |