Steady-state vibration of DFT locomotive cabs.
Thesis DisciplineMechanical Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
Back injuries and other illnesses for Tranz Rails Locomotive Engineers, is claimed to be attributed to vibration of locomotive cabs. The purpose of this research was to conduct a study in order to determine the complex motion of a DFT locomotive cab and to objectively and quantifiably measure the vibration present in the locomotive. This thesis examines the ability of a six Degrees Of Freedom rigid body mathematical model of a DFT locomotive cab to determine the natural frequencies present. The goal was to use this model to provide information on different mount alternatives, in order to reduce vibration. The results of this model were inadequate for the selection of another elastomeric mounting alternative. While experimental test of the locomotive cab showed that the rigid body assumption was valid it was found that there are other continuous vibrations and non-linear effects that are also very important in determining cab vibration. Auto-correlation results from acceleration measurements at the base of the mounts were overlaid with the cross-correlation of the acceleration measurements of the cab side of the mounts. These results showed that the current mounts have 100% transmissibility. In some cases and directions the mount was shown to actually amplify the vibrational input from the locomotive. The amplitude of the steady-state vibration of the locomotive cab that was being transmitted was so great that it rendered the dynamic characteristics of the cab insignificant. From the experimental results, the elastomeric mounts were found to be incapable of attenuating the vibration. In addition, the vibration levels due to locomotive running are found to be well above comfort levels of various publications.