This machine is designed for the primary reduction of clay and shale.  The 5'3" (1600mm) diameter rotating disc is slotted, the slots being fitted with forty hardfaced replaceable knives.  The disc is driven by a 40 HP motor through a vertical type worm gear box and a secondary spur gear box.  Both gear boxes are totally enclosed and running in oil.  The vertical shaft footstep bearing in the base of the spur gear box is fitted with a spherical roller thrust race also running in oil.

The barred and spiked feed roller is placed off centre across the disc and is driven by a 5 HP geared motor through duplex sprockets and chain.  The roller is pneumatically loaded by means of an air cylinder which allows the roller to lift if tramp metal is encountered.  The cylinder which loads the roller, will, by simply moving the valve lever, lift the roller to clear out any obstruction.

Ball and roller bearings are fitted throughout.

The primary clay cutter prosesses average clay and shale of "as won" dimensions, at the rate of up to 50 tons per hour, reducing the material to ½" (12.7mm) size.