Parts n.e.c. of boring or sinking machinery and of derricks, cranes, mobile lifting frames, straddle carriers and works trucks fitted with a crane; parts n.e.c. of moving, grading, levelling, scraping, excavating, tamping, compacting, extracting or boring machinery for earth, minerals or ores; parts of pile-drivers and pile-extractors; parts of snow-ploughs and snow-blowers