The term crush refers to the external force created by the part of the bearing that is exerted over the housing bore when the bearing parts are held in place. This extra material keeps the outer diameter of the bearings firmly against the housing bore when the assembly is torqued to specification.
By increasing surface contact between the bearing and the connecting rod housing bore, crushing reduces bearing movement, helps compensate for bore deformation, and aids in heat transfer. In simple words, the bearing crush is what keeps the bearing in place. Think of it as putting a 10-pound thing in a five-pound bag.
Tactile or locator tabs on the shell that the saddle fits are only meant to locate the bearing during assembly.When the crush is perfect, slightly elliptical bearing spheres conform to a perfect circle when rotated into place. In this way, the crankshaft rotates properly. However, when excessive crushing occurs, the additional compressive force causes the bearings to bulge inward on the parting lines, causing side pinching.