Wheel flat effect on wheel-rail forces on perfect/even track

The green line next to axle-box(left primary suspension spring) demonstrates the variation in wheel vertical displacement as the flattened area of the wheel surface with 6 mm length touches the rail surface. The diagrams with red and green color illustrate the variation in wheel vertical forces to the rail and the wheel vertical displacement respectively. For simplicity in demonstration, the rail is considered without any irregularity or un-evenness.