Oil lubrication is recommended for the nuts. Oil bath or drip lubrication is effective. Oil bath lubrication is suitable for severe conditions such as high speed, heavy load, or high heat generation. It is the best lubrication method because the nuts are also cooled down. Drip lubrication is suitable for medium or low speed and medium or light load. For a less frequent low speed feed, manually apply grease to the shaft regularly or use the oil holes of the nuts for lubrication.