Ball-joint retainers for the pistons of hydraulic motors and pumps

Claim 1

Device for retaining a swivel ball in a socket cavity having a surface of revolution without a supporting ledge extending perpendicular to the axis of the swivel ball comprising a partspherical bottom adapted to cooperate with the surface of said swivel ball, said cavity comprising a frustoconical surface portion extending from said bottom with its major diameter base end contiguous with a surface intersecting siad part-spherical bottom and its minor diameter base end defining the minor diameter of the entrance opening of said cavity; and a retaining member in the form of a split resilient ring mounted in contact with said frustoconical surface and said swivel ball to retain said swivel ball, said retaining member being a unitary member and being shaped in the portion thereof which engages the surface of said swivel ball so that there is at least one fictitious tapered surface tangent both to said retaining member and to said swivel ball in their zone of mutual engagement, the radial crosssectional shape of said retaining member being such that the apex half-angle of said fictitious tapered surface is greater than the apex half-angle of the frustoconical surface of said cavity, and the difference of these respective apex-angles being less than or equal to the sum of the friction angles at the points of contact between said retaining member and said fictitious tapereD surface and between said retaining member and said frustoconical surface.