The magnitude of the load is the factor that usually determines the size of the ball bearing unit. Generally, units with cast iron, stainless steel or composite housings can withstand heavier loads than units with pressed steel housings.
Magnitude of load is defined as:
- very light load: P ≤ 0,02 C
- light load: 0,02 C < P ≤ 0,035 C
- moderate load: 0,035 C < P ≤ 0,05 C
- normal load: 0,05 C < P ≤ 0,1 C
- heavy load: P > 0,1 C
In applications where normal to heavy loads occur, only ball bearing units with cast iron, composite or stainless steel housings should be used. These units are able to withstand the same dynamic and static loads as their insert bearings and are less sensitive to shock loads.
Ball bearing units with a pressed steel housing are designed to withstand light to moderate loads and are not able to accommodate shock loads.
Ball bearing units with housings made of cast iron, composite or stainless steel are able to withstand at least the same dynamic and static loads as the insert bearings they incorporate.
Ball bearing units with a pressed steel housing are only intended for light axial loads, in particular the plummer block units incorporating a rubber seating ring.