Abstract: A pneumatic system for exerting a downward grinding force on the roller assemblies of a roller type grinding mill. The pneumatic system consists of a plurality of resilient and flexible pneumatic cylinders or bellows operatively connected through a crank arm, a horizontal rotatable shaft and lever to the roller assembly. The flexible pneumatic cylinders exert an upward force on the crank arm which in turn exerts a downward force through the rotatable shaft and lever on the grinding roll. Vertical movement and vibration of the roller assembly is absorbed by the flexible cylinder to maintain a steady grinding force on the rollers.

Abstract: A rotary coal feeder having a casing with a rotatable shaft having a plurality of blades defining pockets for feeding coal therethrough. The blades rotate about a hollow core and heated air passes through the core to keep the blades warm and prevent coal from sticking thereto. A chamber at the bottom of the feeder casing also has heated air passing through it to assist in drying the coal. The air exiting from the core and the chamber is directed into the coal stream.