Albert Barnes Commentary Proverbs 20:26

"A wise king winnoweth the wicked, And bringeth the [threshing] -wheel over them." — Proverbs 20:26 (ASV)

The wheel - The threshing wheel (Isaiah 28:27–28), which passes over the grain and separates the grain from the chaff. The proverb involves therefore the idea of the division of the good from the evil, no less than that of the punishment of the latter.