| Abstract |
The vibration environment within a 50 Foot - 70 ton boxcar and its running gear was measured by accelerometers and recorded on magnetic tape. The accelerometers were mounted on the car body floor over the center plate and on the unsprung mass of the trucks. The test consisted of operating a train over specially prepared track at speeds between 10 and 60 mph. The boxcar was run empty, with half load, and finally with a full 70-ton load for each series. The full test program included evaluations designed to determine the effect of load, speed, track irregularities, flat wheels, friction damping, variable rate springs, spring travel, and truck design, on the vibration environment within the car body. The results of these tests are presented in the form of vibration spectrograms, Power Spectral Density Curves, Transmissibility Curves, and plots of acceleration versus speed. It was concluded that an increase in load and spring travel reduced the vibration levels in the car body. All of the new truck designs tested produced reductions in the car body vibration levels. Friction damping levels presently used in freight car trucks were found to be nearly optimum. Flat Wheels produced a tremendous increase in truck vibrations and a smaller increase in car body vibrations. (DOT) |
