Abstract: A wheel truck for a railroad car, including: a front wheel pair assembly and a rear wheel pair assembly; two side frame assemblies, each side frame assembly including a square box and journal-box guides; two spring suspension devices; and a bolster assembly including two ends disposed on the two spring suspension devices, respectively. The bolster assembly includes a pilot hole in the center and two mounting holes on the two ends, the pilot hole is rotationally matched with a cylindrical upper center plate of a car body for transmitting vertical and horizontal forces from the car body, and the two mounting holes are disposed above the two spring suspension devices, respectively. Each mounting hole receives a lower side bearing, and the lower side bearing is matched with a corresponding upper side bearing disposed on each side of the car body for transmitting the vertical load from the car body.