On the Challenges of Quieting a Freight Locomotive Cab Interior

The primary purpose of this paper is to discuss some of the challenges—both from an engineering standpoint and economically—facing the railway industry in improving the noise and vibration characteristics in locomotive cabs. To this end, we will first establish the vibration characteristics of a typical locomotive cab used in freight locomotives in North America. Next, we will evaluate the effect of separating the cab structure from the reminder of the locomotive structure by elastomeric mounts. This cab configuration is commonly referred to as “soft-mounted cab,” in contrast to a “hard-mounted cab,” which is rigidly attached to the remainder of the locomotive structure. The structural dynamics of a production locomotive cab is studied in a laboratory environment. The cab is excited by a hydraulic actuator, in a manner closely resembling field inputs. After establishing the baseline vibrations of the cab, the study presents the results of vibration tests for the soft mounted cab. A comparison between the hard-mounted and soft-mounted cabs indicate that soft mounting the locomotive cab can result in substantial noise and vibration reduction at all locations in the cab, and therefore provide: • more crew comfort, • less equipment damage, and • manufacturing cost savings. The paper will also discuss the effect of the measures that are needed for quieting the cab, such as soft mounting it, on the locomotive manufacturers from an engineering and business perspective.