Abstract: A wheel truck, including: a front wheel pair assembly and a rear wheel pair assembly, two side frame assemblies, two spring suspension devices, and a bolster assembly. The spring suspension devices include a bearing spring unit, a damping spring, and a wedge. The wedge includes a primary friction surface and a secondary friction surface. The primary friction surface is attached to a column surface of the side frame assembly. The secondary friction surface is attached to an inclined surface of the bolster assembly. The wedge has the following structure parameters: ?=16-30°, and ?<tg?<?+?1, in which a represents an included angle between the secondary friction surface and a vertical plane, ? represents a friction coefficient of the primary friction surface, and ?1 represents a friction coefficient of the secondary friction surface.

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.

Abstract: A lower side bearing for a wheel truck, including: a first friction board, a second friction board, an inner pedestal, a bearing sleeve sleeving the inner pedestal, a pressure block, a pressure plate, and an elastic component. The pressure block is disposed on an upper part of the inner pedestal, and the second friction board is disposed on a top of the pressure block. The pressure plate is disposed on an upper part of the bearing sleeve, and the first friction board is disposed on a top of the pressure plate. A friction coefficient ?k of the first friction board and a friction coefficient ?z of the second friction board meet the relation: ?k>?z. The elastic component is disposed between the inner pedestal and the bearing sleeve for controlling a relative position of the inner pedestal and the bearing sleeve.

Abstract: A damping device, including: a wedge assembly having a wedge including a vertical surface and an inclined surface; a primary friction board disposed on the vertical surface; and a secondary friction board disposed on the inclined surface; and a damping spring assembly disposed underneath the wedge assembly. The wedge assembly has the following structure parameters: ?=16-30°, and ?<tg?<?+?1, where ? represents an included angle between a friction surface of the secondary friction board and a vertical plane, ? represents a friction coefficient of the primary friction board, and ?1 represents a friction coefficient of the secondary friction board.

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.

Abstract: A lower side bearing for a wheel truck, including: a first friction board, a second friction board, an inner pedestal, a bearing sleeve sleeving the inner pedestal, a pressure block, a pressure plate, and an elastic component. The pressure block is disposed on an upper part of the inner pedestal, and the second friction board is disposed on a top of the pressure block. The pressure plate is disposed on an upper part of the bearing sleeve, and the first friction board is disposed on a top of the pressure plate. A friction coefficient ?k of the first friction board and a friction coefficient ?z of the second friction board meet the relation: ?k>?z. The elastic component is disposed between the inner pedestal and the bearing sleeve for controlling a relative position of the inner pedestal and the bearing sleeve.

Abstract: A wheel truck, including: a front wheel pair assembly and a rear wheel pair assembly, two side frame assemblies, two spring suspension devices, and a bolster assembly. The spring suspension devices include a bearing spring unit, a damping spring, and a wedge. The wedge includes a primary friction surface and a secondary friction surface. The primary friction surface is attached to a column surface of the side frame assembly. The secondary friction surface is attached to an inclined surface of the bolster assembly. The wedge has the following structure parameters: ?=16-30°, and ?<tg?<?+?1, in which a represents an included angle between the secondary friction surface and a vertical plane, ? represents a friction coefficient of the primary friction surface, and ?1 represents a friction coefficient of the secondary friction surface.