Patent ID: 10212981

Abstract:
A helmet 100 includes a helmet shell 16, an outer liner layer 14 fixed inside the helmet shell 16; and an inner liner layer 12 positioned against the outer liner layer 14; the outer liner layer 14 having a dome-like concave curved internal surface; the inner liner layer 12 having a dome-like convex curved external surface; the said surfaces of the inner and outer liner layers 12, 14 being substantially spherical where they overlap for allowing rotational sliding movement of the inner liner layer against the outer liner layer; a rotation-limiting mechanism being provided for limiting rotation between the inner and outer liner layers; and at least one of the said surfaces of the inner and outer liner layers 12, 14 having recesses 18 therein for weakening the layer and for facilitating crushing of the layer when a sufficiently large radial force is applied, loosening the inner liner layer 12 within the outer liner layer 14.