Automatic nut screwing and unscrewing machine for sleeper

The invention discloses an automatic sleeper nut screwing and unscrewing machine which comprises a base located on one side of a sleeper mold, a ram driven by a ram driving mechanism to be close to or away from the sleeper mold is slidably connected to the base, a plurality of box bodies are installed on the ram side by side, a driven gear is rotationally connected to each box body, and a nut is arranged on the driven gear. The driven gear is provided with a through hole in the axial direction, a tensioning rod penetrates through the through hole, a spline housing is connected into the through hole in a sliding mode, a first compression spring is arranged between the driven gear and the spline housing, and the end of the spline housing is connected with a socket spanner matched with a nut; the ram is further provided with a buffering mechanism for limiting rotation of the tensioning rod penetrating through the driven gear, the ram is provided with a cross beam driven by a cross beam driving mechanism to move