Static load rating (C0) is the maximum radial load the bearing can sustain without permanent deformation. Use this for applications where the load acts in one direction and the joint sees no oscillation, such as a braced structural tie rod.
Dynamic load rating (C) applies when the joint oscillates under load. This is the relevant number for most linkage applications: control rods, actuator clevises, steering arms, conveyor linkages, and agricultural three-point hitches.
How to apply the C/P ratio. Divide the dynamic load rating (C) by your operating load (P). The result is the C/P ratio. A ratio of 2.5 to 3 is acceptable for standard continuous-duty oscillation. For heavy-duty with moderate shock, target 3 to 4. For severe shock loading (agricultural equipment hitting buried obstacles, off-road suspension), target 4 to 5.
Account for peak loads, not average loads. This is where most engineers get it wrong. A conveyor linkage that pulls 3 kN under steady operation may see 9 to 12 kN at startup under full load. If you sized to 3 kN with a C/P of 3, the rod end is running at C/P of 1 during every startup cycle. Measure or estimate peak loads and size to those.
Axial load adds to the effective radial load. Rod ends are primarily radial bearing components. If your application has a significant axial component (more than 20% of the radial load), apply a combined load formula or select a rod end with an explicit axial rating. Most standard rod ends are not designed for sustained axial load as the primary force direction.
Temperature also affects rated capacity. Above 60°C, most bearing manufacturers apply a reduction factor. If your application runs hot, check the temperature correction in the datasheet.