Planetary gear reducer for engineering machinery

The utility model relates to a planetary gear reducer for engineering machinery, which is structurally characterized in that two independent sealing chambers are arranged in a base and are respectively an output driving shaft sealing system and a gear mechanism sealing system; one end of an output driving shaft of the output driving shaft seal is positioned outside the base, and the other end extends into the right sealing cavity; the gear mechanism sealing system comprises a gear ring, a motor connecting cover, a primary sun gear and a planetary gear set, the gear ring is positioned and connected between the base and the motor connecting cover, the gear ring is in meshing transmission with the planetary gear set, and the output driving shaft is in meshing transmission with the planetary gear set; input power of the first-stage sun gear is subjected to second-stage meshing transmission of the planetary gear set and then is subjected to meshing transmission with transmission teeth of the output driving shaft,