Rotary Enginerring Corporation - Hydraulic Expanding Mandrel-CONCENTRIC Our design Rotary CONCENTRICTM Roller Cage/Pin Cage is very sturdy, with solid Rollers which have freedom of rotation about its own axis as well as flexibility in locating diameter, so that wear of Rollers & breakage of roller cage is minimum. The Cage is made out of High Grade Still Material Hardness 60 to 62 HRC for longer life. Use of Roller cages for perfect location and minimum PCD runout is a great help for mass production of Gears These Roller Cages are tailor made for each gear. The Roller diameter and its PCD are made to suit each Gear Data. The Roller are located in each tooth gap so that clamping becomes easier and also ensure perfect location on PCD of Gear thus reducing the runout between bore & PCD of Gears. Normally after heat treatment of Gears, the internal grinding of bore posses a great problem of PCD location. We have solved this problem with the state of the art design of Roller cage.