tilting helmet

from The Collaborative International Dictionary of English v.0.48

Tilting \Tilt"ing\, n.
   1. The act of one who tilts; a tilt.
      [1913 Webster]

   2. The process by which blister steel is rendered ductile by
      being forged with a tilt hammer.
      [1913 Webster]

   {Tilting helmet}, a helmet of large size and unusual weight
      and strength, worn at tilts.
      [1913 Webster]