The Use of Narrowband Low Frequency Air-coupled Transducers for High Speed Detection of Broken Rails

A shell case comprising prefabricated fragments (4), preferably of a material with high density, and a supporting material which surrounds the fragments and together with these forms a connected shell which surrounds the explosive of the shell. The supporting material consists of a completely dense non-compressible material which is permanently connected with the pre-fabricated fragments, for instance a hardenable steel. The shell is preferably manufactured by a powder metallurgical procedure in which the supporting material in the form of a metal powder together with the pre-fabricated fragments (4) are pressed under high all-round pressure and high temperature into a dense compact jacket.