The noise and vibration benefits of soft-mounted locomotive cabs

The primary purposes of this study are to: (1) establish the vibration characteristics of a typical locomotive cab used in freight locomotives in North America; and (2) evaluate the effect of separating the cab structure from the reminder of the locomotive structure by elastomeric mounts. Such a cab configuration is commonly referred to as "soft-mounted cab/spl Gt/CLOSE"/, in contrast to a "hard-mounted cab" that is rigidly attached to the remainder of the locomotive structure. To this end, the structural dynamics of a production locomotive cab are studied in a laboratory environment. The cab is excited by a hydraulic actuator in a manner closely resembling the input the cab is subjected to in the field. A series of tests are conducted to establish the vibration baseline of the cab, and to define how various parts of the cab vibrate. Next, the cab structure is soft mounted and the noise and vibration tests are repeated, in order to establish a comparison between the hard-mounted and soft-mounted cab. The results 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 possibly manufacturing cost savings. The paper provides a detailed description of the setup of the locomotive cab in the laboratory, and the results for some of the noise and vibration tests that were conducted on the cab.