Abstract: A rotatable drum apparatus for use with a drying kiln or a dry grinding mill has a large gear wheel secured to the periphery of the drum, the drum being heated. In order to minimize the generation of undue stresses between gear wheel and drum due to thermal gradients, the apparatus includes a stationary heat shield extending about the gear in thermal stabilizing relation therewith. The arrangement includes air pressurization within the shield and seal means between stationary and rotary components, to limit the loss of heated air from the enclosure, and to preclude the ingress of air and foreign particles into the enclosure.

Abstract: A grinding mill having heavy duty transmission including a hydraulic clutch is provided with an inching capability, a slow running capability, a braking capability and overload prevention, as well as synchronization capability.