Theses and Dissertations

Date of Award

5-1-2026

Document Type

Thesis

Degree Name

Master of Science in Engineering (MSE)

Department

Mechanical Engineering

First Advisor

Constantine Tarawneh

Second Advisor

Arturo Fuentes

Third Advisor

Heinrich Foltz

Abstract

The loading conditions experienced by freight railcar bearings vary as a function of vehicle operating conditions. Under static conditions, bearings are primarily subjected to radial loads transmitted through the wheelset. During operation, however, track irregularities, braking events, railcar load imbalances, and curving introduce complex impact, longitudinal, and lateral forces in addition to the normal radial loading. These lateral forces increase friction within the bearing raceways, which could accelerate wear and potentially lead to premature spall initiation and propagation. While prior research at the University Transportation Center for Railway Safety (UTCRS) has demonstrated that vibration signatures can be used to detect bearing defect development, the influence of lateral loading on bearing performance across varying load and speed conditions remains largely unexplored. A test fixture capable of applying lateral forces up to 50% of the applied vertical load was designed, fabricated, and integrated onto the Single Bearing Tester (SBT) at the University of Texas Rio Grande Valley (UTRGV). A series of experiments was conducted under empty and fully loaded conditions at multiple operating speeds to quantify the effects of lateral loading on bearing temperature and vibration response. The results indicate that using this experimental fixture for the application of lateral load produced an abrupt increase in operating temperature on the inboard side of the bearing, accompanied by a decrease in temperature on the outboard. In experiments performed with a defective bearing, it was noticed that for every 4.45 kN (1 kip) of lateral load, there is approximately a 1°C (1.8°F) increase in bearing operating temperature. The lateral load forces the rollers into a more constrained state against the inboard cone rib, significantly reducing internal clearance and altering the dynamic behavior by limiting their ability to skew. This shift in the internal load path concentrates sliding friction primarily at the inboard rib, creating localized heating while simultaneously decreasing the friction in the outboard cone. Changes in vibration levels were also observed with the introduction of lateral loading on defective bearings. Moreover, applying a continuous lateral load for longer durations produces cyclic temperature trending events exhibited in both unloaded and fully loaded operating conditions.

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Copyright © 2026 Abel David Sanchez Trinidad. All Rights Reserved. https://proquest.com/docview/3371134623

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