The dynamically equivalent axial load is a calculated reference load that reduces a varying or cyclic axial load combination to a constant reference load. It is used to evaluate the service life and load-carrying capacity of ball screws, lead screws, and rolling bearings under actual operating conditions.
Meaning
In practice, constant forces rarely occur on threaded drives, spindles, and rolling bearings. Often, varying, pulsating, or shock-like axial loads act on these components, which significantly affect their service life and wear.
The dynamically equivalent axial load combines these variable loads into a single, constant reference load that has the same effect on service life as the actual load profile.
Calculation
It is calculated based on the individual load values, the respective durations of application, and any load cycles.
For ball screws, it serves as the input value for the service life calculation:
The following applies:
= dynamic load rating of the nut
= dynamic equivalent axial load
Applications
Ball screws: Calculation of maximum allowable loads and service life.
Trapezoidal screws: Estimation of wear and continuous operation under varying axial forces.
Rolling bearings: Conversion of dynamic load profiles to a constant reference force
Summary
The dynamic equivalent axial load is a key parameter for the design, sizing, and service life calculation of screw drives and rolling bearings. It converts real, variable loads into a manageable equivalent load, thereby enabling a reliable assessment of service life under varying operating conditions.