Abstract: Systems and methods centrifugally separate mono nuclear cells from whole blood in a separation chamber. The systems and methods control the exit hematocrit value of red blood cells separated in the chamber by recirculating a portion of the red blood cells removed from the chamber for mixing whole blood entering the separation chamber. The systems and methods also control the entry hematocrit value of whole blood entering the separation chamber by recirculating a portion of the plasma constituent removed from the separation chamber for mixing whole blood entering the separation chamber.

Abstract: A mounting for a stepping motor (42) in a peristaltic pump (20) is provided. The mounting includes a first bracket (81) which rigidly scures stepping motor housing (58) in a radial direction while providing a bearing assembly (96) connecting the first bracket (81) and the stepping motor housing (58) to allow for free rotational movement. A second bracket (62) is also secured to the stepping motor housing (58) which includes at least one spring (72) which dampens tangential forces.