China supplier high quality LAKE Square drive Roller Kelly bushing consists of lower body half, upper body half, roller, roller pin and etc. when the bushing is installed to square kelly or hex kelly, the square part of the lower body half can be fitted in the square of the master bushing. When operating, the rotary table drive master bushing and master bushing drive Roller Kelly bushing and Roller Kelly bushing drive square kelly or hex Kelly to rotate, such is the torque transporting. The lower body half is conically shaped to readily enter the bore of the master bushing and automatically center bushing and drill string within the bore of the master bushing. Inside rollers are journal bearings which are fitted to the roller pin, when kelly rotates and moves downward, the rollers rotates with Kelly, such change sliding friction to rolling friction and minimize the abrasion of the kelly. The bushing is equipped with mud-scrapper assembly to clean the mud. The Square Drive Roller Kelly Bushing provides the following advantages: 1.Pulling out or feeding off string can be done while rotating; 2.Because of its integral construction, it can not fly out and hurts you. 3.The bushing is easily installed into the master bushing, maintaining good alignment; 4.The contact between Kelly and roller is rolling contact, so friction is lower, and weight on bit is accurate; 5.The Kelly has lower wear and has long life.