The hammer consists basically of a striking element which falls freely from rest through a vertical height, selected from Table 2, on to the specimen surface held in a horizontal plane.
The characteristics of the striking element shall comply with Table 1. The fall of the striking element shall be along a guideway, for example three or four rails, with negligible braking. This guideway shall not rest on the specimen and the striking element shall be free of the guideway on striking the specimen. In order to reduce the friction, the length l of the striking element shall not be smaller than its diameter D, and a small gap (for example 1 mm) shall be provided between the striking element and the guideway.
The height of fall shall be as given in Table 2, the equivalent mass stated therein being equal
to the actual mass of the striking element.
Table 2: Shows falling.
|Energy, J||Equivalent mass, g||Fall height, mm, ± 1%|