A sealed wheel case is provided for use with a vibratory device for vibrating aggregate material. The vibratory device includes a frame and a rotating shaft extending transversely across the frame, with the shaft having a wheel. The sealed wheel case includes a housing having a base, a peripheral sidewall, and a cover. The housing is sized to receive therein the wheel and is further adapted to house therein a quantity of lubricating oil for lubricating the wheel. A plurality of attachment bolts are provided for securing the housing to the frame. Each of the attachment bolts includes a shank, an inner end disposed within the wheel case and having an inner contact surface, an inner control washer disposed between the inner contact surface and the housing base, with the inner control washer having a first predetermined thickness. The inner control washer includes an aperture therethrough sized to form with the bolt shank an annular cavity, and an O-ring is provided which is sized for insertion in the annular cavity, with the O-ring having a second predetermined thickness greater than the first predetermined thickness. The bolt further includes an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame. Accordingly, in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing.