version of the holder ring indicated at 34a is shown in fig1 the holder ring 34a is made from a gray cast iron 102 with an aluminum bronze coating 104 applied to the interior surface of the socket 80 the aluminum bronze surface 104 provides a favorable bearing surface for the connecting rod spherical small end as compared to the gray cast iron 102 lubricating oil is introduced between the holder ring socket surface 80 and the connecting rod spherical small end by means of a plurality of grooves 106 preferably equally spaced around the socket surface 80 the grooves 106 are preferably cut into the socket surface 80 at an angle of 30 u00b0 to the horizontal the grooves 106 allow oil into the socket 80 but do not operate to drain oil from the socket 80 the cooling gallery 40 of the spherical joint piston 32 operates properly when it is more than half full of lubricating cooling oil the level of the cooling oil within the piston cooling gallery 40 is maintained by means of the oil dam 54 and one or more drainage grooves 108 equally spaced around the outer perimeter of the holder rings 34 the drainage grooves 108 direct the cooling oil.