Instability Phenomena of a Passenger Coach, Caused by Internal Yaw Damper Flexibility

It is described that severe hunting may be caused by yaw damper flexibility. A case where this happened is described. The problem was studied by use of the computer package Gensys. A new yaw damper with smaller internal flexibility was introduced, which turned out to solve the problem. It is also indicated that very small changes of parameters may change the level of critical speed very much.