EngineerBenchEstimating carriage loads on paired linear rails
A moment can place more load on one rail than the other even when the total force is shared symmetrically. This model combines a direct load share with a moment contribution based on rail spacing and carriage count. It represents the arrangement stated by the calculator, not every possible rail installation.
Match the catalog's rating basis
Use dynamic and static ratings for the actual carriage and check whether catalog life is based on 50 km or 100 km. A rating quoted on one distance basis cannot be substituted without checking that basis. The model's life estimate also depends strongly on the most heavily loaded carriage.
Geometry and mounting still matter
Increasing spacing can reduce the moment-induced load in this arrangement. Combined moments, preload, mounting errors, and unequal carriage stiffness are not resolved. Use the manufacturer's load-combination method for a final selection, especially when loads act in several directions.
Separating force rating from installation geometry
A wider rail spacing gives a moment a larger resisting lever arm in the supported arrangement. That can reduce the additional load assigned to the more heavily loaded row. Adding carriages also changes the assumed share, but only when the actual structure and mounting stiffness allow the model's load distribution. A count entered in a field does not ensure equal physical sharing.
Use the load at the governing carriage for the life relationship rather than dividing the total by every carriage and ignoring the moment. Check whether the catalog's dynamic rating refers to a stated travel-life basis, and enter that basis consistently. Static capacity is a different comparison and should not be substituted for the dynamic rating. Preload, orientation, multiple simultaneous moments, and manufacturer correction factors can change a final selection. The worksheet helps assess the represented symmetric layout; it does not replace a rail supplier's combined-load method. Confirm mounting surface accuracy, lubrication, fastening, and the stiffness of the moving structure before specifying a carriage size.
Formula
Maximum load = direct share + moment/(spacing × carriages per row). Life = catalog base distance × (C/P)³.