A rail system for large turret bearing includes a turret bearing support structure, a rail support ring provided with a L-shaped cross section including an inward directed wedge mating face, at least two rings of radially elongated segment bolt holes, and an outermost ring of wedge bolt holes, a plurality of rail segments together forming a complete circle with an outer radius slightly smaller than the radius of the wedge mating face of the rail support ring. Each segment includes a sloped outer wedge mating surface, a downward facing contact surface with threaded bolt holes corresponding to the bolt holes in the rail support ring, an upper largely horizontal surface, and an inner largely vertical surface.