My Krauss Maffei Summer
I had a summer job with the SP in 1965. As a graduate in Mechanical Engineering from MIT with an interest in railroad operations, I was assigned to work with a team of engineers from KM working on fatigue failures of the transmissions and cardan shafts.
One possible anecdote: I recall being told that one cardan shaft failure had resulted in the broken shaft swinging around under the locomotive and banging its way through the floor of the locomotive’s cab -- but I can't confirm the truth of this.
To determine the cause of this and other less dramatic failures, we instrumented one of the units with strain gages at various points on the locomotive’s trucks to monitor forces on the wheel axles, transmissions and cardan shafts. We ran the instrumented locomotive hauling freight back and forth between Roseville and Sparks recording measured forces. Before each run we'd calibrate our instruments by jacking the trucks up off the rails and applying known torques.
The strength of the KM diesel hydraulic's traction was that all the axles on a truck were linked mechanically, this strength also proved to be a weakness. The wheels experienced wear unevenly. As they wore the "cross talk" forces measured by the strain gages increased. The increased forces increased the uneven rate of wheel wear setting up the conditions for a fatigue failure of the cardan shafts that linked the wheels in a truck or the gearing at each axle.
The German engineers found that the SP was not machining the wheels of each truck to the same profile as routinely as it was done in Germany. When we had the wheels on each truck re-machined to matching profiles it greatly reduced the stresses recorded by our instruments.
The locomotive engineers driving the locomotive were all impressed by its ability to start a train on a hill. This greater tractive efficiency was a reason for the SP's purchase as they were dissatisfied with the EMD locomotives at the time.
Our instruments were in a caboose coupled right behind the locomotive. We had a portable generator on the back ‘porch’ of the caboose to provide power for the instrumentation. At one point the caboose got up to 116˚F in the yard at Roseville due to the afternoon sun and the strip chart recorders. No AC. We drank sodas to keep cool and the Germans commented that a drink of equal amounts of Seven-up and beer was called "beer for bicyclists".
Another vivid memory I have of that summer was that on one crossing of the Sierra I slipped on the walkway while transferring transmission fluid (some fluid may have spilled on the walkway). Luckily I caught myself with the railing.
All in all it was a great summer. The locomotive maintainers, engineers and operating people were great to work with.
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