Motive Power (a Wabtec Company) engaged CTLGroup to conduct tests on MP1114 locomotive trucks to be used on Massachusetts Bay Transportation Authority (MBTA) four-axle AC-traction diesel-electric locomotive for commuter trains. The objectives of the tests were to evaluate the structural strength and durability of the truck frame design, to validate the finite element model and results obtained during analysis, and to satisfy the requirements of MBTA Technical Specification SR-41. The guiding test standards used were UIC 615-4, 2nd Edition, February 2003, “Motive power units – Bogies and running gear – Bogie frame structure strength tests.” Consideration was also given to the requirements of AMTRAK Specification No.865, November 2008, “Specification for Electric Locomotives.”
Tests
Four separate test were developed and executed; three static load tests and a 10 million cycle multi-phase fatigue test.
CTLGroup developed a detailed test plan which was pertinent to successful testing when performing many complex testing scenarios. The test plan highlighted the loading diagrams, fixture designs, installation instructions, load at every step, equipment components, instrumentation components and channels, data acquisition details, work sheets, check sheets, calibration plans, and schedule. The static test cases considered exceptional loads, simulated main in-service loads, and simulated in-service loads which accumulated to 26 static load combinations.
These load scenarios were established from calculated vehicle dynamic forces that were predicted to occur in service. The fatigue portion of the testing consisted of a three phased cyclic load profile. Synchronized loads were varied such that distributed asymmetric loading was achieved throughout the truck structure. Fatigue testing was performed to evaluate if the design and materials can endure the cycling loads or stress ranges, which the structure will be subjected, during its service life. The equipment used included eight actuators and calibrated load cells, 12 LVDTs, 133 channels of strain gages, four instrumented and calibrated fixtures, and a high-speed data acquisition collection system. Advanced customized control logic was also utilized.
CTLGroup determined that the MP1114 locomotive trucks met all structural test requirements.
