F-units, brake systems                                                  TT00040




05/02/02 7:39

Bill Kuebler

All available photo evidence shows that the Phase 3  conversions occurred well before the Loewy scheme was first  applied to a set of units (6506 in March 1953). If memory  serves, this conversion was done to sets 6503-6506 about the  time, or just before the time, they got F-5As to replace the  middle F-3B unit--October 1948. Not sure about when they did  6500-6502, but would guess about the same time or very  shortly thereafter. By the time 6500-6502 got their F-7As to  replace one of the original F-3B units in each set (Spring  1949), I believe the As had been converted to Phase 3. By  the time of the Loewy scheme, all the major conversions and  louvre add-ons (middle louvre on most B-units, for example)  had already been completed. This last remark concerns only  the F-3/5/7s, since the first F-9s were acquired in 1954,  during the Loewy era. The F-9s went through no major  modifications that would affect their outward appearance,  except for the various conversions back and forth between  passenger and freight service, which resulted in engine  number, steam generator, and paint scheme changes.    Now you've given me a second reason to go through all my  F-unit pics/slides. Will do so one of these days. Should be  able to ID most of the individual units as to the color of  those anti-slip treads on the noses and maybe nail down the  conversions for 6500-6502. This much I can say right now:  The white treads were a 1960s thing, and it involved more  than a few units.    For you modelers out there (and historians for that matter),  here's one to ponder: Ever notice that on trains 25 and 26  during the period 1956-62, whenever there was one F-9A in a  three-unit locomotive (trioed with F-3/5/7s) the F-9A was  almost always the trailing unit? Rarely was it the lead  unit. The NP even went so far as to turn sets around, if  necessary, so as to make the F-9A the trailing unit on  trains 25 and 26. This rather consistent pattern did not  hold true for other passenger trains in that era. Lots of  photos show trains 407-408, for example, with the single  F-9A leading a pair of F-3s. Nor did this pattern hold true  after 1962, even though there were still many instances of  one F-9 unit being trioed with two of the older models on  trains 25 and 26.    Just for the fun of it, let's call this trivia stumper #2.  Any ideas? All your hints appear in the paragraph above.    While we're at it, let's add question #3 to the series.  Throughout the diesel era (not just 1956-62), whenever a set  of passenger units included an F-9A and an F-3/5/7A, several  NP enginemen in passenger service (I have no idea how many,  but it was more than a few) very much preferred to have the  F-9A in the lead, given a choice. The reason for this is  related to the reason behind question #2 above. And one more  hint: this preference for the F-9A in the lead did not hold  true for freight unit sets. With mixed F-3/5/7 and F-9  freight unit sets, they didn't seem to care which type they  had in the lead.    This could be rather interesting. I'm curious to see what  ideas you come up with. Admittedly, the answer to #3 here  involves a very tiny detail, one that few fans would be  aware of, but that enginemen were acutely aware of. NP vets,  especially enginemen, are disqualified from this trivia  quiz. (Actually, they're over-qualified for it.)  Detail variation, aint scheme, passenger, F3, F5, F7, Pine Tree, Loewy, 1940s, 1947, 1948, skid strips, modifications  Compiler  C Frissell

05/04/02 16:30

Bill Kuebler

1. In a mixed locomotive consist, why would the F-9A usually  be the trailing unit on trains 25/26 during the period  1956-1962?    LWBaxter nailed it.    The story of NP's electro-pneumatic brake system on trains  25/26 is a long one and full of controversy and interesting  tidbits. This is the short version of the story, with lots  of details left out, but enough to cover our purposes here  and a little more. NP air brake manuals referred to the  electro-pneumatic brake system with the initials "SA", so  that's what I'll call it here. "SA" refers to the  electro-pneumatic system, and "AU" refers to the standard  automatic brake system. These were the letters used in the  master controllers, too.    The SA system was used on the NCL for a short time beginning  in 1952, when those trains were fully streamlined and when  there were only F-3/5/7 units on the roster. By the way,  NP's F-units, both freight and passenger, all models, all  came equipped with the 24RL automatic brake valve system.  This was a very popular brake valve among enginemen. It was  very precise. As one once told me, "If you wanted to set  seven pounds, you got seven pounds, not ten." The newer 26L  type was much less popular. Also, the 24RL was a pressure  maintaining system, a nice feature that offset leakage  losses in the train line.    The SA system, which involved extra components, including  controllers in the cab units, was intended for use only on  the NCL. No other NP trains used that system. The SA system  also involved special equipment on all the NCL fleet cars.  Not just any car could be used in the NCL during those years  if SA operation was to occur. For example, only a few of the  500-517 series day coaches were initially equipped to be  "trainlined" with the NCL (this included PA components,  too). Essentially, the SA brake system worked much like a  straight-air system (hence, the letters "SA"), at least in  terms of the results it produced. It was very fast acting  and all the cars' brakes applied or released virtually  simultaneously, a remarkable feature that the standard AU  system did not have. The 24RL brake valve was used with  either system, but it functioned differently in SA mode than  it did in AU mode.    Anyway, the NP discontinued SA use shortly after it was  first used, but left most of the system components in the  diesel units and cars. Then came the F-9s, beginning in  1954. They also had 24RL brake valves. When they first  showed up, the NP was not using the SA system.    Then Jess Cannon replaced George Ernstrom as General  Mechanical Superintendent on 3/31/56. One of Cannon's first  decisions was to reinstate the use of the SA system on the  NCL. So as to be able to use F-9s in locomotives, the NP  equipped the passenger F-9s with hoses and connections for  the SA system, but not controllers. Thus, in order for the  SA system on the NCL to be functional, no F-9 in the consist  could be the lead unit. If an F-9 did lead, the AU mode had  to be used. This did happen on occasion, but not often. The  requirement for F-9s to trail for SA mode operation seldom  posed any problem, as there were not that many F-9s then. On  occasion, a three-unit consist of all F-9s appeared on the  NCL, and in that case, the AU mode was used. As for other  trains, it didn't matter. All passenger units were  compatible for any position in the consist, brake wise, if  the AU mode was used.    Finally, the NP permanently discontinued the use of the SA  system in May 1962. By mid-1964, all SA brake system  fittings, hoses, cables, and components on units and NCL  fleet cars had been removed by various shop forces during  scheduled maintenance.    Q #2: With passenger locomotive consists, why would some  engineers prefer the F-9 in the lead versus an older model?    This is an obscure matter. It fits under the heading "Human  Factors," a phrase nonexistent in the NP days, even though  human factors were still factors because humans were  involved.    This preference among some engineers was true throughout the  1954-1970 era. And, we are assuming here that we're talking  24RL brake valves in all units, even though one or two F-9s  were given 26Ls toward the end, as previously mentioned.    The difference was in the brake valve handle quadrant. The  passenger F-3/5/7 units all had "inside quadrant" valve  handles. All the other F-units--passenger and freight F-9s,  and freight F-3/5/7s--had "outside quadrant" valves. For  those unfamiliar with F-unit cabs...The automatic brake  valve handle in an F-unit was on the brake pedestal, which  was in front of and slightly to the right of the engineer.  (Incidentally, this meant that unless he wanted to imitate a  pretzel, the engineer had to use his right hand on the brake  valve handle rather than his left, as was the case on most  other locomotives, including steam, and this "right hand  use" was something that some men didn't care for, as it  seemed awkward to them and they never got used to it. But  that was the arrangement in all F-units. Other than that,  F-units drew few complaints and were quite popular.)    These brake valve quadrants involved a series of irregularly  spaced and sized groves and notches that determined the  brake valve "schedule," a fancy way of saying "various  positions, each of which did certain things." The 24RL brake  valve position/schedule involved the following, in the order  shown (beginning from a handle position furthest from the  engineer and going toward him):    Full Release (usually just called "release")  Run ("running" with brakes released)  1st Service  Service Lap (sometimes called "Lap")  Service (this was a range of positions, the furthest right  of which was called "Full Service")  Emergency    From Full Release to Emergency, the handle moved through a  roughly horizontal arc that was about 90-degrees, maybe a  little more.    Anyway, the various notches and stops of the quadrant on an  "outside quadrant" were just that, on the outside of the  quadrant where they could be seen. On "inside quadrant"  types, they were hidden out of view under a metal cap over  the valve, a cap that sort of resembled a miniature Chinese  hat. On the inside quadrant types, the engineer had to find  the various stops and notches strictly by feel; he could not  see them. The really irritating part of this was that the  Full Service position's stop was easily overridden or  overshot, so that it was very easy to accidentally place the  brake valve handle into emergency when only a full service  application was desired. On the outside quadrant types this  was no problem, as the engineer could easily see what he was  doing, but on the inside quadrants, it was all done by feel.  The handle's position in the horizontal arc provided some  visual cues, but they were not precise by any means. Feel  was necessary for precision. And because the stops and  notches were irregularly sized and spaced, there was always  that question; "Is this the stop/notch that I think it is?"    Generally, the men in regular passenger service for long  periods of time got used to this and it was no big deal to  them. But men who were in freight service and then made a  trip in passenger service found this to be a problem. A few  of them complained quite a lot about those "inside quadrant"  valves. Of course, some men learned quickly and never  complained. They just did their jobs and got by.    I have been told that those inside quadrants were necessary  in order to use the SA system, although my air brake manuals  and materials do not make this point obvious. I believe that  was the case, however. An inside quadrant valve could not be  rendered an outside quadrant merely by removing that cap.  Switching from one type to the other would require a whole  new quadrant assembly. Even though the NP got rid of the SA  system in 1962, they did not change the valves.    As for the SA system itself, that's yet another interesting  story. Like most things, the system had significant  advantages, but also some drawbacks. For one thing, the  "schedule" of the brake valve was entirely different in SA  mode as compared with AU mode, even though the engineer used  the same handle. This, in itself, took some getting used to.  Moreover, there was no "Emergency" position in SA mode. In  an emergency situation, if the engineer placed the handle  all the way over to the emergency position associated with  AU mode, out of habit, so as to get an emergency  application, nothing would happen in SA mode except for this  popping sound. He would have to move the handle back the  other direction a ways to get an application! This was very  counter-intuitive, and one of the nuances of the SA system  that some engineers disliked very much. There were other  aspects of SA mode that were quite controversial, too. At  least one engineer on the Fargo Division disliked the SA  mode so much that he preferred to just use AU mode whenever  he had train 25 or 26, even though supervisors frowned on  that. At one time, the NP even installed seals to prevent  men from switching over to AU mode except in an emergency.  In 1957, Warren McGee's father was on train 26 and  experienced a problem with SA mode during a brake  application for a 40 MPH curve at MP 42 west of Columbus. By  the time he converted over to AU and set the air, they were  into the curve at 70 and nearly dumped the train into the  Yellowstone River.    Human Factors was very much present in NP operations, even  though they didn't have that name for it.   consists, F3, F7, F9, electro-pneumatic brake system, 24RL brake valve, NCL, North Coast Limited, valve handle quadrant, cab, SA, AU  Compiler  C Frissell