A bogie, comprising: an axle, wherein a middle portion of the axle is downwardly recessed to form an receiving space, and journals are arranged symmetrically at both ends of the axle; wheels, wherein each of the wheels is connected to a respective one of the journals by a bearing; and a buffer device located in the receiving space, wherein the buffer device comprises: a primary spring assembly arranged on the axle; a secondary spring assembly arranged on a top of the primary spring assembly; and a slewing ring arranged on a top of the secondary spring assembly and configured to be connected to a vehicle body to transmit a traction force or a braking force to the vehicle body, wherein the axle comprises: an axle body; and two axle heads, wherein one of the two axle heads is arranged at one end of the axle body, and the other one of the two axle heads is arranged at another end of the axle body, the two axle heads and the axle body form the receiving space, and each journal is arranged on an exterior side surface of a top end of a respective one of the two axle heads, wherein the primary spring assembly comprises: a primary spring pallet; and two primary elastic members, wherein the two primary elastic members are symmetrically arranged at both ends of the primary spring pallet, and each of the primary elastic members is arranged between the primary spring pallet and a respective one of the axle heads for connecting the primary spring pallet and said respective one of the axle heads with each other. an axle, wherein a middle portion of the axle is downwardly recessed to form an receiving space, and journals are arranged symmetrically at both ends of the axle; wheels, wherein each of the wheels is connected to a respective one of the journals by a bearing; and a buffer device located in the receiving space, wherein the buffer device comprises: a primary spring assembly arranged on the axle; a secondary spring assembly arranged on a top of the primary spring assembly; and a slewing ring arranged on a top of the secondary spring assembly and configured to be connected to a vehicle body to transmit a traction force or a braking force to the vehicle body, wherein the axle comprises: an axle body; and two axle heads, wherein one of the two axle heads is arranged at one end of the axle body, and the other one of the two axle heads is arranged at another end of the axle body, the two axle heads and the axle body form the receiving space, and each journal is arranged on an exterior side surface of a top end of a respective one of the two axle heads, wherein the primary spring assembly comprises: a primary spring pallet; and two primary elastic members, wherein the two primary elastic members are symmetrically arranged at both ends of the primary spring pallet, and each of the primary elastic members is arranged between the primary spring pallet and a respective one of the axle heads for connecting the primary spring pallet and said respective one of the axle heads with each other. a primary spring assembly arranged on the axle; a secondary spring assembly arranged on a top of the primary spring assembly; and a slewing ring arranged on a top of the secondary spring assembly and configured to be connected to a vehicle body to transmit a traction force or a braking force to the vehicle body, wherein the axle comprises: an axle body; and two axle heads, wherein one of the two axle heads is arranged at one end of the axle body, and the other one of the two axle heads is arranged at another end of the axle body, the two axle heads and the axle body form the receiving space, and each journal is arranged on an exterior side surface of a top end of a respective one of the two axle heads, wherein the primary spring assembly comprises: a primary spring pallet; and two primary elastic members, wherein the two primary elastic members are symmetrically arranged at both ends of the primary spring pallet, and each of the primary elastic members is arranged between the primary spring pallet and a respective one of the axle heads for connecting the primary spring pallet and said respective one of the axle heads with each other. an axle body; and two axle heads, wherein one of the two axle heads is arranged at one end of the axle body, and the other one of the two axle heads is arranged at another end of the axle body, the two axle heads and the axle body form the receiving space, and each journal is arranged on an exterior side surface of a top end of a respective one of the two axle heads, wherein the primary spring assembly comprises: a primary spring pallet; and two primary elastic members, wherein the two primary elastic members are symmetrically arranged at both ends of the primary spring pallet, and each of the primary elastic members is arranged between the primary spring pallet and a respective one of the axle heads for connecting the primary spring pallet and said respective one of the axle heads with each other. a primary spring pallet; and two primary elastic members, wherein the two primary elastic members are symmetrically arranged at both ends of the primary spring pallet, and each of the primary elastic members is arranged between the primary spring pallet and a respective one of the axle heads for connecting the primary spring pallet and said respective one of the axle heads with each other.