Usually, railway vehicle consists of rail car and two bogies. These are the main parts of a railway vehicle. Usually unnoticed by the passengers, they are very important for safe rail operations. The main functions of the bogies are to support rail car body, to ensure stability of a rail vehicle on both tangent and curved track, to provide good ride comfort of passengers by absorbing vibrations generated by a short and long-wave irregularities of the railway track. These can be either motorized, that is, there is a motor on engine embedded in it or trailed, that is, a bogie without engine. The main elements of the bogie are the frame, the wheel sets and the suspension system. A motorized bogie has additionally the traction motor, wheel gear and transmission system. Here we can see a motorized bogie. The motorized means that the motor is embedded in the design of the bogie. Here we can see the motor and here we can see the gearbox and here we can see the wheel set. Suspension system. Suspension system of the bogie consists of a primary and secondary suspension. The primary suspensions connect a wheel set to the frame of the bogie, while the secondary suspensions connect the frame to the car body. Design of the suspension system can differ depending on the bogie, but the main functions of the suspensions are the same. This is the bolster air spring, the secondary suspension of the bogie suspension system, the secondary suspension is responsible for the comfortable ride of passengers and absorb the low frequency vibrations of the bogie.