Abstract: A power transmission device comprises a central shaft supporting an axially fixed and rotationally free sleeve with an axially displaceable drive wheel and a fixed pulley for receiving input power mounted thereon, an output sleeve being rotationally free but axially fixed with respect to the central shaft on which output sleeve is fixed and with an output sprocket and a rotationally fixed but axially displaceable take off wheel mounted thereon, and two transfer disks with flat round surfaces for engaging the outer surfaces of the drive wheel and power take off wheel to transfer power from the drive wheel to the take off wheel in accordance with the ratio of the relative distances of the drive wheel and take off wheel to the center of the transfer disks, direction of rotation of the take off wheel reversing as the axial displacement of the take off wheel causes it to pass the center of the transfer disks. The transfer disks are releasibly engageable with power take off wheel and drive wheel.

Abstract: A subatmospheric air pressure is applied to the bottom of a grain bin so that the air flows down through the grain from a top opening in the bin. Heated air, at atmospheric pressure or above, is introduced into the bin above the top of the grain. This air may be distributed above the grain to flow down through it.