a heavy duty rotary disc - type wood chipper containing a knife clamping system that conducts the impact and shearing loads acting upon the chipper knives along two primary axes which allows for more efficient dissipation of the impact loads and a reduction in the deleterious effects of off - axis loads resulting in the ability to use smaller holding bolts and smaller knives in the system without adversely effecting either the ability of the knives to stay fixed to the disc or the quality of chips produced .