Noise and vibrations in locomotive cabs can significantly affect crew performance and cause long-term ailments, such as hearing loss, fatigue, and low back pain. Methods to reduce noise and vibrations have been implemented for the high frequency range but resulted in low frequency resonances. These resonances can exacerbate low frequency vibrations (<0.5 Hz), which can cause motion sickness. In addition, a tonal noise exists in the 50 to 200 Hz frequency range, which is more annoying than broadband noise, and which is not addressed in current noise reduction methods based on A-weighted noise metrics. To reduce vibration, the innovative approach proposed here will consider isolating only the floor of the cab rather than the whole cab as was previously reported in the literature. The isolation is achieved using nonlinear springs and dampers that provide isolation at high frequencies while avoiding resonances at low frequencies. The smaller inertia of the floor, controls, and crew, as compared to the entire cab, makes the necessary components much less expensive. To reduce the tonal noise in the range 50 to 200 Hz, active noise control is used in the vicinity of the crew seats. Analyses have shown that this new approach is very promising, and demonstrations are planned for mockups of locomotive cabs.
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