Conventional Locomotive Coupling Tests

Research to develop new technologies for increasing the safety of passengers and crew in rail equipment is being directed by the Federal Railroad Administration’s (FRA’s) Office of Research, Development, and Technology. Crash energy management (CEM) components which can be integrated into the end structure of a locomotive have been developed: a push-back coupler and a deformable anti-climber. These components are designed to inhibit override in the event of a collision. The results of vehicle-to-vehicle override, where the strong underframe of one vehicle, typically a locomotive, impacts the weaker superstructure of the other vehicle, can be devastating. These components are designed to improve crashworthiness for equipped locomotives in a wide range of potential collisions, including collisions with conventional locomotives, conventional cab cars, and freight equipment. Concerns have been raised in discussions with industry that push-back couplers may trigger prematurely, and may require replacement due to unintentional activation as a result of service loads. Push-back couplers are designed with trigger loads meant to exceed the expected maximum service loads experienced by conventional couplers. Analytical models are typically used to determine these required trigger loads. Two sets of coupling tests are planned to demonstrate this, one with a conventional locomotive equipped with conventional draft gear and coupler, and another with a conventional locomotive equipped with a push-back coupler. These tests will allow a performance comparison of a conventional locomotive with a CEM-equipped locomotive during coupling. In addition to the two sets of coupling tests, car-to-car compatibility tests of CEM-equipped locomotives, as well as a train-to-train test are also planned. This arrangement of tests allows for evaluation of the CEM-equipped locomotive performance, as well as comparison of measured with simulated locomotive performance in the car-to-car and train-to-train tests. This paper describes the results of the coupling tests of conventional equipment. In this set of tests, a moving locomotive was coupled to a standing cab car. The coupling speed for the first test was 2 mph, the second test 4 mph, and the tests continued with the speed incrementing by 2 mph until the last test was conducted at 12 mph. The damage observed resulting from the coupling tests is described. The lowest coupling speed at which damage occurred was 6 mph. Prior to the tests, a one-dimensional lumped-mass model was developed for predicting the longitudinal forces acting on the equipment and couplers. The model predicted that damage would occur for coupling speeds between 6 and 8 mph. The results of these conventional coupling tests compare favorably with pre-test predictions. Next steps in the research program, including future full-scale dynamic tests, are discussed.