US Patent 7448795 Preconditioner having mixer shafts independently driven with variable frequency drives

An improved, dual-shaft preconditioner (10, 70) is provided having independent drive mechanism (18, 20, 78, 80) operatively coupled with a corresponding preconditioner shaft (14, 16, 74, 76) and permitting selective rotation of the shafts (14, 16, 74, 76) at rotational speeds and directions independent of each other. The mechanisms (18, 20, 78, 80) are operatively coupled with a digital controller (60) to allow rotational speed and direction control. Preferably, the preconditioner (10, 70) is supported on load cells (62, 100) also coupled with controller (60) to permit on-the-go changes in material retention time within the preconditioner (10, 70). The preconditioner (10, 70) is particularly useful for the preconditioning and partial gelatinization of starch-bearing feed or food materials.