Patent ID: 7441718

Claim:
Apparatus for mechanically reducing wood debris, comprising: a housing having a material infeed chute; a mechanical reducing device disposed within said housing operative to reduce the wood debris material fed into said housing; at least one feed drum supported within said housing between said infeed chute and said mechanical reducing device for rotation about a generally horizontal axis and further supported for selective raising and lowering within the housing relative to a lower material support to provide a variable width feed gap to accommodate variations in the size of the wood debris material introduced to said feed gap; a hydraulic motor coupled to said at least one feed drum and to a supply of hydraulic fluid under pressure to drivingly rotate said at least one feed drum, said fluid pressure being variable in response to varying loads exerted on said at least one feed drum; and a hydraulic feed control system coupled to said at least one feed drum and to said supply of hydraulic fluid and operative to exert a downward force on said at least one feed drum in response to application of a load on said at least one feed drum and thus an increase in said hydraulic fluid pressure associated with said at least one feed drum.