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On a few occasions in past issues of CROSSROADS, this column has used the "questions from the audience" format (Some of you might know who has made this term famous). Such will be the approach for this month; I selected some of your most asked, as well as most interesting questions which deal with new technology and their applications.
These inquiries come from both the agreement and non-agreement sides of the workplace.
SD90/43MAC LEAD ONLY GENERAL NOTICE
One of the questions about was: "Did this notice mean that you were confined to having only one MAC locomotive in the consist?"
No, it did not.
Another question was: "While setup as trailing locomotives, why would the ICE screens always remain dark?" Because upon performance of the trailing position instructions outlined by the notice, this was the by-product.
Now to the big question: "What was the reason for its issuance?" Because there were a number of actual cases in which SD90/43MAC locomotives, while in the trailing position, would self-activate the forced leading feature, resulting in the locomotives of the lead consists "fighting" each other with braking action. The engineer would be notified of this occurrence by seeing on the lead unit brake cylinder pressure fluctuations between 40 and 72 lbs.
There is more to this story; but to try to keep it short: Another factor involved with this process was troubleshooting on the EPIC air brake and Integrated Distributed Power systems (All of the culprit locomotives had, at that time, just been retrofited with the IDP control system).
The techniques flushed out the troublemaker (It was a software glitch in the EPIC air brake system).
The remedy has now been applied to the entire SD90/43MAC locomotive fleet, so this general notice should, by now, have been cancelled.
NEXT TOPIC: DPU MATTERS
2. Can you still legally perform the brake pipe leakage test on a DPU train, even though prior to its execution, the remote consist was already positioned in BV OUT mode?
Answer to the first question: As long as the remote consist is cut in, linked and functional, the train still complies with operative equivalent device rules. Even in the BV OUT mode, the radio signal from the lead consist will go to the backup emergency valve and initiate proper emergency responses on the remote consists.
Answer to the second question: The brake pipe leakage test may be performed on a DPU train if it is in this state of being. It will not affect the results of the test; your main difference here will be that the brake pipe will not be reduced at that point in the train.
Important Messages: Remember...The use of the BV OUT position on a remote consist is for cause, such as positive determination that the automatic brake is not functioning properly.
Sorry folks, but to use this as a technique for trying to offset "dynamiters" does not fit into this category.
Also... If you are in the BV OUT mode, and then for some reason, the remote consist picks up an unexpected air flow while the train is in a communications loss status, the result will be a Comm Loss Idle down of the remote consist.
OTHER SD90/43MAC QUESTIONS
Answer to the first question: This area serves more as an advisory zone; it uses the yellow color because short time ratings do not exist in the AC Traction system.
Depending upon a number of factors, if the locomotive remains in this area consistently for long time periods, it could cause the locomotive to eventually begin derating the tractive effort output (this process will occur automatically).
Notification of this to the operator will be via crew messages displayed on the ICE screen.
Answer to the second question: Both AC (Alternating Current) and DC (Direct Current) Traction models of locomotives have electrical current production in common. Current equates to power (or in this case, the level of braking strength). When track speeds go higher, the levels of current begins to drop lower. So the lower levels of current translates into the lesser outputs at higher speeds, thus the lesser dynamic braking levels.
AN INTERESTING ROLE REVERSAL
An engineer working an empty DPU coal train to Mc Alester had this to occur to with a C44AC remote unit. When I looked at the locomotive for him, it had the display screen message of WARNING: Locked Axle Detected. I corrected the problem, and the remote gave him no more headaches for the rest of his trip.
So this left me wondering: How was this operating situation made possible? Answer: This was an unplanned actual demonstration of AC technology, and an advantage it carries over traditional designs.
GE came out with a different way of control for the dynamic braking side from the power throttle side. So in a case such as this one, dynamic braking would still be available. What was probably the bandit was a bad speed sensor.
(GM also has an AC Technology advantage story; this tale will be featured next month).
SLATED FOR NEXT MONTH
SD90/43MAC IDP UPDATE
Since my feature in the April 1998 issue of CROSSROADS which looked into why this was happening, significant progress has been made toward an overall cure.
Most of the SD90/43MAC fleet have been outfitted with an upgraded Cab Consolidation Computer, which has more storage and logging capacities that can handle much better the inputs from the ICE, EPIC air brake and IDP systems.
The story does not end here; research is still ongoing in order to make furthur enhancements which will make these operating systems even more reliable.
6000 HORSEPOWER AC TRACTION UNITS IN TEXAS
The first model to "cross the finish line" at the Red River bridge was GE's C60AC locomotive. It did so in a way you probably would not have expected (Goodness knows I sure didn't): On a DPU coal train. The locomotive was UP 7001, featured on job CRMCL-18 (Rochelle mine to Coleto Creek, Texas). It arrived in Fort Worth on May 22nd with this arrangement:
This job returned to Fort Worth as a CCLRM-22 on May25th; it was in the conventional format, with yet another twist: The UP 7001 was the new leader of the consist.
On this job, I got to speak with the conductor; he observed that with this consist makeup "It would pick up speed at the top end a lot faster. The locomotive would load up very fast."
GE would have a repeat performance in the arena; DPU coal train job 2CCDSA-26 (Cordero mine to San Antonio), which arrived into Fort Worth on July 2nd with this arrangement:
Its return trip to Fort Worth was on July 6th in DPU format as a 2CSACD-30, with 133 empties 4221 gross tons.
GM has had only one appearance of their entry into the 6000 horsepower market; that being SD90AC locomotive UP 8503. It came into the Centennial yard facility on train MPSFW -31 (Parsons, Kansas to Fort Worth) June 1st.
The unit left Fort Worth June 3rd on job MFWNL-03 (Fort Worth to North Little Rock). This locomotive was on its way to VMV Enterprises in Paducah, Kentucky from the AAR-TTC in Pueblo, Colorado for painting and modifications work.
During its stay, I had the opportunity to perform a walk around inspection of this locomotive. I also took lots of notes (I always take the approach that you might not have another opportunity like this); the items which I will remember the most vivid: The size of the 16V265-H diesel engine, along with the two turbochargers applied (Yes folks, both of them are quite large).
The size of the dynamic brake grids also caught my attention, since this locomotive model has a maximum braking effort rating of 115,000 lbs. It was also outfitted with the IDP system.
MY CLOSING OBSERVATION
7-98