My Krauss Maffei Summer
Mark Hanson 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. Return To Main Page |