A theoretical relationship for basic dynamic load rating based on a th
ree-parameter life equation for a linear motion ball guide (LMBG) syst
em is derived, including the effect of crowning on, guide block, by ca
lculating accumulated stress cycles on rail and guide blocks, rolling
body load and equivalent average ball load. The values for basic dynam
ic load rating are then calculated for different strokes, load eccentr
icities and conformity factors. A life test is carried out for both th
e LMBG system and component. The test data are analyzed by three-param
eter Weibull distribution and the effect of crowning is clarified.