the present disclosure relates to a size reduction apparatus such as a granulating machine of the type for cutting plastics and the like . the granulating machine includes a chamber provided with a driven rotor having a plurality of cutting elements mounted on the periphery thereof , each cutting element having in turn a plurality of spaced cutting knives . the cutting knives cooperate with stationary bed knives to comminute materials fed into the cutting chamber . the downstroke side of the cutting chamber is further provided with an access opening normally closed during cutting operations by a cover , which may be of particularly heavy slotted construction and which provides a backup surface for the material being comminuted . the disclosed granulating machine is particularly useful in comminuting large chunks of plastic material such as heavy purging , thick sheet and cast blocks . machines of this type are designated as hog type granulators in the industry . accordingly , the constructional configurations herein disclosed are particularly useful in hog type granulators . specifically , the particular design enables the accomplishment of heavy granulating tasks without stalling and with relatively low power requirements .