What do radial bearing and pressure bearing mean in physics?

[Femme_physics]

What do "radial bearing" and "pressure bearing" mean in physics?

(This is NOT a homework question)

I am told that this board is supported by two bearings: Radial bearing C, and pressure bearing O. Then they write something I can't even begin to translate, it looks as though it's written in really bad Hebrew, and over-technical language for our level. I'll try to translate it:

The pressure bearing from the cable added to the radial forces the forces acting acting along the y axis.


http://img683.imageshack.us/img683/4516/thehelle.jpg

What do "radial bearing" and "pressure bearing" mean in physics?

 

[EWH]

I believe a radial bearing is just a standard bearing that supports against radial forces, while a pressure bearing (more often called a thrust bearing) is designed to take a force along the shaft axis as well.

 

[RedX]

I think EWH is correct. So a pressure bearing would for example be for the shaft of a blender used for baking, and a radial bearing would be for the driveshaft of a car.

 

[my_wan]

To make it more obvious from the picture look at what happens when you put a weight on that platform. The rope between B and D is offset from the Y axis. So the weight will create a force pulling C away from the wall while O is pressed tight against the wall (Though there are many other counter forces as well). Without bearing C it would rotate away from the wall and O is merely being compressed against the wall. Hence the radial and pressure labels.


Since the distance between O and B is greater than O and A (113.137) the greater the distance between O and D the more free it will be to rotate without the bearings to prevent it. It comes down the the fact that a force exist pulling C away from the wall rotating the platform (radial bearing), but O will not.

 

[Femme_physics]

Let me see if I get it straight with vector notation

http://img97.imageshack.us/img97/8921/withyous.jpg

Forget whether it's the right direction or not, that I'll get in calculation. But in terms of numbers of vectors, did I get it right?

 

[EWH]

If you are specifying the forces provided by the bearings on the shaft OC, then the vectors at O look correct, but the vectors at C should only be the two perpendicular to the one you drew (xz).

 

[Femme_physics]

Ah, so radial means it allows movement at Y, not denies movement just at Y. Now
I get it. Thanks