Patent ID: 7090157

Claim:
A material reduction apparatus comprising: a rotatably mounted rotor having radial projections; an anvil adapted to pivot into two or more positions, at least one of the positions being a closed position wherein the anvil is positioned in proximal relation to the projections of the rotor; a conveying mechanism for conveying materials to be reduced into the rotating rotor and projections, and to be carried by said projections for impacting said anvil to reduce in size components of said materials; a screen also adapted to pivot into two or more positions, at least one of the positions being a closed position wherein the screen is positioned in proximal relation to said projections of the rotor for engaging said components to further reduce the size of the components and to provide passage of said further reduced components through screen openings in said screen and out of the path of the projections for collection and conveyance away from said apparatus; said anvil and screen mounted to have common pivotal movement away from said rotor projections and as pivoted away from said projections providing a bypass for materials carried by said projections to thereby avoid anvil and screen reduction; and a pivotal resist member adapted to provide a resistance to said pivotal movement while permitting said pivotal movement and thus providing said bypass of materials in response to a determined releasing force generated by reduction-resistant material, wherein the resistance when the anvil and screen are in the closed position is different from the resistance when the anvil and screen are pivoted away from the projections, the pivotal resist member further adapted to allow the screen and anvil to reestablish the closed position, wherein said pivotal resist member includes a latch mechanism and further including a cam member engaging a cam surface, said cam member being biased by a first biasing member, and said reduction by said screen and anvil urges said cam member against said first biasing member for retraction and release of said cam member in response to excessive reduction resistance and allows for reattaching once the material has bypassed.