Piston guiding element, rock drilling machine and method

A piston guiding element arranged for providing support for a front end portion of a reciprocating percussion piston of a rock drilling machine, the element being a sleeve-like piece mountable inside a body of the rock drilling machine between the percussion piston and the body, the element comprising:

• a first end, an opposed second end, an outer surface and an inner surface, wherein the first end is arranged to be facing towards an impact direction of the percussion piston, wherein the opposite second end is arranged to be facing towards a return direction of the percussion piston and is provided with a braking recess having a greater diameter on the inner surface, and the braking recess extending a first axial distance from the second end towards the first end, the inner surface of the element having a first groove, which is located at a second axial distance from the braking recess;
• at least one radial opening located between a bottom of the first groove and the outer surface, the inner surface including a first axial section disposed between the braking recess and the first groove, and a second axial section disposed between the first groove and the first end;
• and
• at least one separate bearing sleeve mounted inside the element and provided with the first and second axial sections, wherein at least the mentioned first and second axial sections are made of a slide bearing material, wherein the outer surface includes a second groove, the at least one radial opening extending to a bottom of the second groove, and wherein the outer surface includes at least one third groove extending from the second end to the second groove.