|
Probably the earliest attempt to adapt the standard gyratory for reduction crushing service was the short-head arrangement, which consisted simply of an abbreviated crushing head, installed in the standard machine, with concaves to match, This device did not prove to be very successful; crushing stresses were concentrated at a point where the top shell was ill fitted to withstand them, and the throw at the point of discharge was too small to take full advantage of the increased diameter of discharge opening . Chronologically, this adaption is a rather venerable one; it antedates by a number of years the more serious efforts to develop special fine-reduction crushers, a development which did not gather headway until shortly after the end of World War I.
It would be a difficult matter to ascertain just where this development has its inception; probably a great deal of parallel work was being done at the time by the various crusher builders. One of our own early experiments along these lines was the installation of special concaves in several of the N° 4 crushers in the Thornton plant mentioned above to reduce the crushing angle. The results were encouraging enough to start a more thorough investigation into the design of crushing chambers.
|
