TRACK ROLLER is also called lower roller or bottom roller, which is designed to carry the majority of the excavators weight and dynamic forces through the tracks, and onto the ground. Forged from deep hardening steel and heart treated for internal strength to resist bell mounting and to increase rebuilding ability. 2 pieces roller shell rim. Heat treated shells for body strength and longer wear life. Heat treated for a deep uniform hardened deep that providers wear life equal to link wear life.