Shape detail of a piston to avoid jamming within a distorted bore

摘要

A piston (21; 104) to be mounted inside a cylindrical bore (46; 117) has a cylindrical surface (32; 114) provided with at least one axially extending deepening (31; 116) for accommodating a thermal distortion of the cylindrical bore (46; 117). Preferably, the piston is used in a piston valve as a valve control member or turbine as a variable nozzle control member.