SUMMARY From a classical study of railway stability, the author shows how the equations of motion of a railway-car having: either a counter hunting damping device, between wheelset and truck frame, or a direct or crossed stiffness device between front and rear wheelsets are modified. The critical speed is determined by eigenvalues of matrix A (9,9). From the critical speed variations as a function of: CR typical value of counter hunting damping device, K′ b or K′ b typical value of direct or crossed stiffness, we can say that: the influence of these original systems on the critical speed is more interesting for higher values of equivalent conicity γe, for lower values of γe, the critical speed is high already. the best values of CR of K′ b (or K′ b ) are defined from curves given the critical speed as a function of CR or K′ b (orK′ b ). a crossed stiffness device is more interesting that a direct stiffness device.

Stability of railway-car running at high speed

Matrix (A) shows the dynamic behavior of a high speed free truck running on an aligned track under optimal geometric conditions. The maximum running speed will be lower than the critical speed inherent to the system which is determined by the first eigenvalue of the matrix for which the real part is small and positive. The increase of this critical speed has been observed by an increase of the connection stiffness between car-body and truck. In fact, the car-body truck connection includes more than the classical connection. It includes hydraulic damping devices whose force-displacement diagram is similar to that of a friction damping device. After considering the elastic deformation of the connecting system ensured by the damping devices between truck and car-body, and the connecting springs between truck and car-body mounted is parallel, we observe a drawback torque relative to the truck. This characteristic can be compared to an hysteresis cycle.

R. Joly

Papers

Impact of the nonlinear connection torque between truck and car-body on the transversal stability of a railway-car

Impact of the Nonlinear Connection Torque Between Truck and Car-Body on the Transversal Stability of a Railway-Car