An assembly for rotating a chain or toothed belt includes a shaft and a sprocket rotatably mounted on the shaft. The sprocket includes a plurality of teeth configured to engage the chain or toothed belt. The assembly further includes a shield assembly covering at least a portion of the sprocket. The shield assembly has an interior groove formed therein defining an enclosed interior space. Each of the teeth of the sprocket rotate through the enclosed interior space during a full rotation of the sprocket.