About Bearing Calculations (AutoCAD Mechanical Toolset)

There are two types of bearing calculations, static and dynamic.

The type required depends on the type of load being used.

• Dynamic calculation is required for revolving bearings. Result is the Adjusted Life Rating. It is the life associated with 90% reliability with contemporary, common used material quality, and under conventional operating conditions. With the number of revolutions, the life in working hours can be calculated. The rating life calculation can be started when inserting a bearing as an additional selection criterion or as a calculation without inserting a bearing. Therefore there are some differences in the command sequence.
• Static calculation is required for bearing-suffering loads in standstill, swinging movement, or bearing-suffering loads at small numbers of revolutions (n<20 1/min). The result is a Static Safety Factor.

Two kinds of calculation types can be distinguished:

• Stand-alone calculation (static calculation), when you launch calculation through the AMBEARCALC command.
• Shaft Generator calculation (dynamic), when bearings are inserted from the database (fasteners) or in Shaft Generator mode.

The calculation can be restricted by

• Geometric: The inner and outer diameters and the width of the bearing can be restricted.
• Lifetime (for dynamic calculation): Minimum and Maximum bounds of life L in number of revolutions [1/min] or in working hours [h]
• Safety (for static calculation): Minimum and Maximum bounds of static safety factor fs.

Bearing types for the stand-alone bearing calculation

The stand-alone calculation is independent from the fasteners. There is a difference to the shaft generator calculation; for the stand-alone calculation, it is possible to calculate the load ratings also. To do this, you must distinguish between more bearing types than for simple calculation:

Radial Ball Bearings: Radial (Normal / Filling Slot / External Align), Angular, Self-Aligning, Magneto, and Thrust Ball Bearing.

Roller Bearings: Radial (Cylindrical Roller Bearing / Tapered Roller Bearing / Needle Roller Bearing with Machined Rings / Needle Roller Bearing Drawn Cup / Spherical Roller Bearing), Thrust (Cylindrical Roller Bearing / Tapered Roller Bearing / Needle Roller Bearing / Spherical Roller Bearing).

All thrust ball bearings and radial bearings are single - or double - row bearings (except magneto ball bearings, which are only single row bearings).

Bearing types for shaft generator bearing calculation

Bearing types for shaft generator calculation:

Radial Ball Bearings: Radial (Angular / Self-aligning / Magneto), Thrust Ball Bearing, Roller Bearings Radial, and Thrust.

All thrust ball bearings and radial ball bearings can be single - or double - row bearings (except for Magneto Ball Bearings, which are only single row bearings).