center line of the ball track and the longitudinal axis in the inner joint part the center line of the ball tracks departs radially inwardly a second reference radius centered in the point of intersection of a perpendicular line on the tangent at the center line of the ball track and the longitudinal axis in the outer joint part the center line of the ball tracks towards the aperture end moves radially outwardly beyond said first reference radius in the inner joint part the center line of the ball tracks towards the attaching end moves radially outwardly beyond said second reference radius application_number US 57589709 A description fig1 a to 1 c will be described jointly below a joint 11 comprises an outer joint part 12 an inner joint part 13 torque transmitting balls 14 as well as a ball cage 15 the cage comprises a spherical outer face 16 which is guided in the outer joint part and a spherical inner cage face 17 which is guided on the inner joint part with said second contact not being compulsory the balls 14 are held in circumferentially distributed cage windows 18 in the ball cage 15 in a joint center plane em the outer joint part 12 is shown to comprise a longitudinal axis l 12 and the inner joint.