Ball bearing, in particular piston rod ball bearing and piston rod with ball bearing

1. A connecting rod for a variable compression ratio internal combustion engine, comprising: an upper piston rod bearing located on an upper end of the connecting rod, wherein the upper piston rod bearing is connected to a plurality of actuation pistons to adjust an effective length of the connecting rod by actuating the upper piston rod bearing into different angular positions due to reciprocation of the plurality of actuation pistons, wherein the actuation pistons each include a ball bearing that provides a ball head arranged at a lower end of the actuation pistons and supported in a ball head receiver, wherein the ball head is secured at an outer surface of the ball head in the ball head receiver by a retaining ring against sliding out of the ball head receiver, wherein the ball head receiver includes an undercut integrally provided with the ball head receiver in one piece at an open end of the ball head receiver, wherein the undercut secures the retaining ring in the ball head receiver in an axial direction of the ball head receiver, wherein the ball head receiver includes a cambered base portion which is adjoined by a cylindrical cavity in the axial direction of the ball head receiver, wherein the retaining ring is applied against a wall of the cylindrical cavity with a preload, wherein the retaining ring has shoulder that is oriented radially inward with respect to the ball head at a face of the retaining ring oriented towards the ball head in an installed condition of the retaining ring, and wherein the retaining ring includes a convex camber oriented in a radially inward direction of the retaining ring.

2. The connecting rod according to claim 1 , wherein the retaining ring is interrupted at its circumference.

3. The connecting rod according to claim 1 , wherein the retaining ring is made from plastic material.