Abstract: A rotary shaft bearing isolator seal where the shaft extends into dry comminuted material providing a stator having a very small tolerance between the rotor on the shaft and the stator containing downwardly sloping circular portions adjacent complimentary inwardly extending and outwardly extending portions of said rotor.

Abstract: System for controlling the discharge rate of a material feeder. A weight scale connected to the material is sampled and the samples input to a digital processor. The digital processor determines for consecutive time intervals during discharge of said material, a weight loss over the time interval. The weight loss for the interval is compared with a desired weight loss which is calculated from a desired setpoint material discharge rate. The resulting error is averaged with subsequent errors to form a control signal for the material feeder. The calculation of errors over each subsequent interval increases the resolution of the control signal, increasing the ability to control discharge rates to compensate for changes in material density which otherwise affect discharge rates.