Line-contact-type spherical bearing for connecting piston to connecting rod

A piston machine, comprising at least one cylinder having a longitudinal axis, a piston axially movably guided in the cylinder, a connecting rod connecting the piston to a crankshaft, the connecting rod and the piston each defining spherically-shaped bearing surfaces for connecting the connecting rod and the piston with each other in an articulated manner, the connecting rod defining a radially outwardly facing spherical surface portion which is arranged concentrically with the spherically-shaped bearing surface of the connecting rod, the piston having a piston wall and a bottom, the piston wall and the bottom defining a recess, the end of the connecting rod facing the piston being sealingly received in the recess, the surface of the recess and the spherical surface portion of the connecting rod defining a hollow space, and the piston bottom defining a bore for effecting communication of fluids between the interior of the cylinder and the hollow space, wherein the piston wall has an inwardly facing projection, the projection serving to positively lock the spherical surface portion of the connecting rod in the recess, and wherein the piston wall defining the recess is cylindrically-shaped, the cylindrically-shaped piston wall extending in axial direction essentially over the entire axial length of the area of the spherical surface portion of the connecting rod, so that contact exists between the cylindrically-shaped piston wall and the spherical surface portion along a line of contact.