Pressurized fluid mechanism such as a hydraulic engine

A pressurized hydraulic fluid mechanism comprising:

• a cam;
• a cylinder block mounted for rotation with respect to the said cam about a rotation axis and including at least one cylinder in said cylinder block;
• at least one piston mounted for axial sliding in said cylinder;
• a girder operatively coupling said piston to said cam,
• said girder slidably mounted inside a radial cut formed in said cylinder block, the walls of said cut forming an extension of said cylinder;
• said girder positioned adjacent to said walls parallel to the axis of said cylinder;
• a removable strip interposed between each wall of the cut and the portion of girder facing it, said strips each fixed on one said wall of the cylinder block or on said girder, the surface of at least one of said wall on which is fixed said strip or the face of said strip which faces said wall having a degree of roughness of at least
• 0. 25 .mu.Ra
• 15 .mu.Rt
• 8 .mu.Rp.