The ‘cam tree', a cylindrical beam 6 metres long, pulled along by a driving belt and leaning on the wheel's axis, operates the mallets by spinning round and round. Its cams, or protruding spurs, knock against the base of the ‘sleeve' of the mallet and raise it. Its own weight then makes it fall again, crushing the rags contained in the stack. For each mallet there are 4 cams. All along the tree, the spurs are situated in order to prevent the mallets from rising in unison. They strike one after the other and the reason for this will be explained later.