a roller clutch case comprises two molded halves that snap fit into retention grooves on the cam race when inserted from opposite axial directions . the retention features of the cage halves that fit within the retention grooves are inherently stiff , and occupy most of the circumferential extent of the cage halves . narrow grooves in the cage halves allow the entire structure to shrink inwardly and re expand , so as to allow the retention features to snap into the grooves in spite of their stiffness . in operation , high pressure oil injected between the cage halves pushes the cage halves axially outwardly , but the cage halves are securely retained by the stiff retention features . the oils is substantially trapped between the cage halves by the biasing of the same retention features into the sides of the retention grooves , with only the relatively narrow grooves providing any leak points . close clearance cross bars in the cage halves help prevent oil migrating to the grooves .