what is the difference between back-to-back & face- to-face arrangement of angular contact bearings?

Answer 1

Is the "cup" the back or the front?

The center of reactive load is the vertex of a cone defined by a surface normal to the cup face. The difference between back-to-back and front-to-front is how far apart these two vertices are for the two bearings.

The further apart the vertices are, the more rigid the set is going to act (remember, nothing is really "solid"; everything is made of "jelly" and we are just talking about how stiff a "jelly"...). Therefore, you should mount these "cups in" to maximize the spread of the reactive vertices.

Watch your preload also. Use a castle nut, and be sure to generate the required preload before locking the nut down.

The advantage of angular contact is that it is "preloaded"; you can generate a loading that has to be overcome by the overhung transverse load before the bearing can lose contact and cause any kind of chatter or wobble.

Answer 2

The back to back arrangement is more rigid; you'd use it for a short shaft with an overhung load. The face to face arrangement is less rigid; you'd use it with a long shaft with another radial bearing on the other end.

http://i35.photobucket.com/albums/d194/mekaniker/fun/brgs2.gif

http://i35.photobucket.com/albums/d194/mekaniker/fun/brgs5a.gif

Answer 3

When two bearings are placed on the end of a shaft either the two outer races are touching each other or the inner races are touching.