Bearing Length and Shaft Diameter Calculation

[yanikomer]

Hello everyone,

I m working on a project that I want to create linear motion to carry a load which is constructed eccentricly as you see in the picture.

I am looking for the equations about calculating the lineer bearing length and shaft diameter.

In this construction, I am using two bearings and pulling the moving object up by a force between bearings.

Many Thanks

yanikomer

 

[Q_Goest]

You can do a free body diagram to determine loads on the bearing. There's a moment on the bearing caused by the eccentric load. That moment is then resisted by the vertical column where the bearing is located.

In general, linear bearings aren't great at resisting moments like this. A better solution is to have two linear bearings, one above the other so that they resist the moment produced by the eccentric load by having a pure lateral load at each bearing. That way, neither bearing is actually resisting the moment.

Linear bearing load capacities are given by the supplier. Check the supplier's catalogs for values. Note that the bearing capacities given in these catalogs (for rolling element type linear bearings) are "dynamic load" ratings, similar to the dynamic load ratings for rolling element bearings, so to get any significant life out of them, you should also perform a B10 analysis on the bearings just as you would a rolling element bearing.