When the inside and outside boundary dimensions of a thrust bearing are limited, but additional capacity is required, enough axial height is generally available to create a stacked assembly.
Stack assemblies are created by adding load-equalization races or spacers ground in matched sets that enable shared load distribution. Stacks may be made from cylindrical, spherical, or tapered roller thrust bearings.
The most common stacked bearing is a simple tandem cylindrical roller thrust bearing. However, multi-high assemblies of three, four or five high have also been successfully designed.