Piston for radial piston hydraulic engine and method for making same

A method of manufacturing a piston for a hydraulic motor having radial pistons, said piston comprising a body having a guiding and sealing surface, a base, and a top, in which method a cradle-shaped recess is provided in the top of the body, and, on the edges of said recess that are situated at the top of the body, stop surfaces are formed for retaining a cradle-shaped journal-bearing lining that is disposed against the surface of said recess;

• wherein the stop surfaces are formed by deforming towards the inside of the recess at least portions of the edges of the recess, in which portions the wall of the body is thinner, and, on the edges of the recess, retaining surfaces are formed for retaining a roller inserted into the recess, by deforming portions of the edges of the recess towards the inside thereof.

A piston for a hydraulic motor having radial pistons, said piston comprising a body having a guiding and sealing surface, a base, and a top, which top is provided with a cradle-shaped recess whose that are situated at the top of the body offer stop surfaces for retaining a cradle-shaped journal-bearing lining that is disposed against the surface of said recess;

• the stop surfaces for retaining the lining being formed over at least portions of the edges of the recess, in which portions of the wall of the body are thinner and which portions are deformed towards the inside of the recess, the edges of the recess offering retaining surfaces for retaining a roller inserted into the recess, said retaining surfaces being formed over at least portions of the edges of the recess that are deformed towards the inside of the recess,
• wherein at least one edge of the recess has at least one local zone in relief, comprising at least one internal projection or at least one internal setback, extending over a fraction of the length of said edge.