COUPLING SOCKET

A coupling socket for coupling to a coupling ball. The coupling socket has a concave coupling receiving area with a main insertion direction for the coupling ball, and a substantially semispherical lubricant cap with an end face edge is arranged in the coupling receiving area, wherein the convex exterior of the lubricant cap contacts the inner wall of the coupling receiving area over the surface thereof, and the concave interior of the lubricant cap has a receiving area for the coupling ball. The coupling socket has an insertion aid in the coupling receiving area, the end face edge of the lubricant cap, when viewed in the main insertion direction, is located behind the insertion aid, and the insertion aid completely covers the end face edge of the lubricant cap.