GEMAC CMC20 Rail Grinder is a self-propelling machine with 20 grinding stones. It is able to treat corrugation and restore rail profile on main line, switch and crossing. The grinder is mainly applicable to grind and profile the rails in switch section. GEMAC CMC20 can efficiently remove rail defects from switch section, rails between switch center and tie rail top as wave abrasion, side abrasion, and abrasion between rail tread and gauge angle on the track with introduced 9＃、12＃、18＃、30＃、38＃switches and 50、60、75kg/m rails. The rail will have good profile and smooth surface after grinding operation, so impact from switch section upon rolling stock and maintenance for switch sections will be reduced, running speed and stability of locomotives when negotiating the switch sections will be increased as well as seating comfort for passengers, additionally, service-life of rails will be extended.