29 / | HD | METAL WORKING |
592 | DF | METHOD OF MECHANICAL MANUFACTURE {54} |
888 | DF | .~ Prime mover or fluid pump making {12} |
888.4 | DF | .~.~ Poppet or I.C. engine valve or valve seat making {6} |
888.45 | DF | .~.~.~ Composite or hollow valve stem or head making {3} |
888.452 | .~.~.~.~ Including extruding |