Rolling contact

(mechanics) Contact between bodies such that the relative velocity of the two contacting surfaces at the point of contact is zero.

Contact between bodies such that the relative velocity of the two contacting surfaces at the point of contact is zero. Common applications of rolling contact are the friction gearing of phonograph turntables, speed changers, and wheels on roadways. Rolling contact mechanisms are, generally speaking, a special variety of cam mechanisms. The concepts of rolling contact are used in the study of antifriction bearings and in the study of the behavior of toothed gearing. See also Antifriction bearing; Cam mechanism; Gear.

Pure rolling contact can exist between two cylinders rotating about their centers, with either external or internal contact. Two friction disks (see illustration) have external rolling contact if no slipping occurs between them. The rotational speeds of the disks are then inversely proportional to their radii.

Rolling friction disks.