Dear Endri,

Inertia Im is the integral of distance to rotational axis to the square times the elemnt mass.

Im = Integral(y^2*dm)

For rim drag, see:

http://www.saimh.co.za/beltcon/beltcon9/paper918.html

Success

Teus ■

Rim Drag:

A typical simple tests is to wrap a string around the idler roller shell and let hang a length of string below roller where slotted washers are added till rim rotates at low speed with known washer mass added at tangent to rim. This is called the breakaway rim drag and can be simulated with various temperatures, but not roller loads. This includes the bearing, grease and seal resistance at onset of rotation.

Idler roll assembly rim drag can be defined by:

1. Roll diameter

2. Bearing size, type, and load dependent losses inclusive of all related items including grease packing pressure - should not overgrease - some do.

3. Grease type and viscosity properties with speed and temperature for selected bearings

4. Roll RPM - high RPM > 700 will have exponentiallly increasing viscous drag and highly dependent on grease and bearing type and size

5. Seal system and colomb loss

associated with seal type and their internal losses which might include grease drag in seal or assembly sensitive drag loss in seal - had experience with US mfgr idler arriving on site with 17 times expected seal drag - so high the empty belt drag exceeded motor capacity. Months later same mfgr. did it again. Go figure. ■