Cylinder block comprising piston-holding means

An assembly comprising:

• a cylinder block having a plurality of recesses extending radially around a central axis, and leading to an outer periphery of the cylinder block;
• a plurality of pistons, each disposed in a recess of the cylinder block having a cylinder-of-revolution cross section around a piston axis extending radially around the central axis, and mounted sliding radially relative to the central axis, each of the plurality of pistons having a body and a crown suited to come into contact with a multi-lobe cam, the crowns having the shape of a cylinder of revolution and two planar ends each in a plane perpendicular to the central axis and defining guide surfaces;
• and
• a holding element extending over at least part of the outer periphery of the cylinder block, the holding element comprising a plurality of guide portions, each partially blocking a recess of the cylinder block, so as to come into contact with a planar end of the crown of a piston so as to accomplish the guiding in translation of each of the pistons in their respective recesses,
• wherein
• the holding element comprises two indexing means cooperating with two indexing means of the cylinder block so as to hold the holding element under a traction force when positioned around the cylinder block.