Early devices for testing hardness were developed by McCormick and Schellenberger
(1960) and Young (1962). Young used a ‘model handling system’ in which pellets could
be subjected to typical actions encountered in the handling of pellets. This model system
was further used as a control for comparison of various other test devices (see Pfost,
1963) such as the Farmhand tester, tumbling can device and the Stokes hardness tester.