a sealed wheel case for use on a vibrating aggregate processing device comprises a housing sized to hold a rotatable wheel supported on a shaft , the housing having a base , a peripheral sidewall , and a cover . the cover includes an aperture adapted to receive therethrough a driven portion of the shaft . a seal is disposed adjacent the shaft and the aperture , and an annular baffle is mounted to an inside surface of the cover and extends into the wheel case . the annular baffle is positioned on the inside surface of the cover to generally surrounding the shaft and the seal , and a plurality of attachment bolts are arranged to secure the housing to the frame .