F-units, rooftop cooling coils                                        TT00045




09/10/02 9:42

Bill Kuebler

I'd love to  > hear from  > someone who knows exactly how these appliances  > functioned. It appears  > they may have had something to do with steam generation on  > passenger  > units, but that doesn't comport with their appearance on  > freight F-9s.    I doubt very much that they had anything to do with steam  generators, at least not directly. There were too many NP  units that never saw passenger service and, thus, never had  steam generators that had these cooling coils. Although it  is possible this roof appliance was for some other system,  the coil appears to be cooling piping associated with the  air brake system. If so, they are there to provide a way of  cooling compressed air or, if there are other cooling coils  elsewhere on the unit, they provide additional cooling for  compressed air. The coil provides a long pipe that, by its  very length, permits sufficient heat transfer from warm,  compressed air to atmosphere as that air flows through the  pipe on its way to either a reservoir or a cylinder, as the  case may be. As air is compressed, it warms up considerably,  and before the compressed air is used in the air brake  system, it usually has to be cooled first (and water drained  as the air is cooled). There are a number of places that  such a cooling pipe can exist on a diesel unit. If you study  other models, and the manuals that depict their design,  interiors, etc., you will see these cooling devices on  almost every unit, in some location. In some cases, even  though units already had them, more cooling was thought to  be needed, so additional cooling coils were added somewhere  else on the unit, to improve the compressed air system. The  question then becomes, "Why here and not elsewhere?" for a  given cooling coil. The answer to that can have to do with  lots of things, especially regarding NP's F-units. Two items  come to my mind that might have had something to do with the  roof placement on SOME units: water tanks along the A-units'  sidewalls (wall tanks, as crews called them), and the  presence of a steam generator or associated equipment taking  up space that otherwise could have been used for additional  compressed air cooling. NP added sidewall water tanks to all  its passenger F-3/5/7/9 units shortly after delivery. NP was  very big on carrying lots of water and minimizing water  stops, especially after 1952. The water-baggage cars on  trains 1,2,25,26 indicate this.    >  >  > Here's what I have gleaned so far:  >  > 1) All F-9 As and Bs, in freight and passenger service,  > appear to have  > been equipped with rooftop cooling coils on delivery in  > 1954-56.    I agree.    >  >  > 2) Some earlier-model F-units in passenger service were  > subsequently  > retrofitted with rooftop coils when shopped. The earliest  > photos for  > which I have seen retrofit roof coils are from 1961 (F-3B  > no. 6504B)  > and 1962 ( F-7As no. 6506A and 6508C, F-3B no. 6509B).    You can add the years 1958 (6507B) and 1959 (6507A) to that  list. See my list of individual units below.    > By the  > mid-1960s, a good share (but not all) of NP's F-3 and F-7  > units in  > passenger service had received roof coils. It appears the  > two FP-7As  > never had them and perhaps the so-called F-5s didn't  > either.    I recall no photos of an FP-7A that show the roof coils, but  I do recall seeing one of an F-5A (6506C) that has it--taken  at Fargo in 1966. Can't put my finger on the image at the  moment, but the view stands out vividly in my mind, so am  adding it to my list below. The image stands out so vividly  account the occasion. The malfunctioning unit had been taken  off train No. 1 and the photo shows the lonely A-unit  standing on an aux track west of the 13th Street Underpass,  a very unusual scene.    >  >  > 3) Freight service F-3s, F-5s and F-7s did not appear to  > be fitted  > with roof coils, with at least one exception.    Four exceptions: 6005C; 6005B (re# 6553B in 1962); 6006B  (re# 6551B in 1959); and 6006C (re#6552B in 1960). All four  were originally passenger F-3Bs from original sets  6503-6506.    > Venerable F-3B no.  > 6005C was captured in 1965 (Kuebler p. 110)sporting a  > distinct set of  > roof coils, but the unit appears freshly painted in  > black-and-yellow  > livery. If you look closely, I just now noticed, you  > can even make  > out the top of a steam generator vent cap poking up from  > the hind roof  > panel, passenger-style.    This is correct, although the steam generator itself had  been removed. Some (or most) of the fittings and piping were  left in the unit, however. Ditto the other three  ex-passenger F-3Bs listed in the preceding comment, all  three of which were converted back to passenger service, and  steam generators re-installed, as indicated. The fresh paint  on the page 110 photo is simply account a standard  repainting job as part of the routine, four-year major  maintenance program.    > This suggests to me that unit 6005C might  > have done some time in passenger service shortly before or  > after 1965,  > but I have found no record of such in my reading.    See above two comments and the note for this unit in the  list below.    >  >  > The take-home message for modelers seems to be: If you  > are doing a  > 1960s-era F-3 or F-7 in passenger colors, you had better  > find a  > prototype photo of the unit you're modelling if you want  > to make sure  > to get the roof nits correct.    Exactly, but add F-5A to the models you listed above, and  include the 1950s era as well. More comments about this  below. Meanwhile, to help you modelers do this, I have a  list for you below that you might find useful.    > Otherwise, if you're modelling a freight  > unit, leave roof coils off, unless it is an F-9, or 6005C    or any of the other three ex-passenger F-3Bs (6005B, 6006B,  6006C, or their pre-1/50 freight numbers)    > --then do  > them.    > Note: 6005C might have possessed all the customary  > steam  > generator appendages while in freight colors, but the  > freight F-9s  > didn't--they just had the coils, with the hind roof panel  > blind.    Correct, except for two ex-passenger F-9As (7051A and  7052A), which still had some steam generator fittings in  them. Unit 7051A went back to passenger service as 6705C in  1966.    When it comes to "patterns" regarding NP F-units'  appearances and appliances, there were very few consistent  patterns. In almost every "pattern" there were exceptions at  one time or another, on one unit or another. As for the  cooling coil discussed in this thread, the moment you think  there might be a pattern, along comes a photo to prove it  wrong. Therefore, *look at photos* to be sure about your  work. I just went through many of my F-unit color slides (I  didn't even bother with my photo collection, for it is much  larger, less organized, and it is probably unnecessary to  look into it anyway, account the slide collection being  sufficient for this purpose). A list appears below of only  those units where the angle of view of the left side of the  unit is such that the matter of the coil being present or  absent is certain, except the one or two noted otherwise.  Bottom line: these images are conclusive regarding the units  indicated on the dates shown.    For the freight F-3/5/7 units, I intentionally focused  mostly on late dates, since that would show no retrofitting  and probably cover the unit's entire NP service life. For  freight F-9s, I looked at all my slides, since these units  were very consistent. For passenger F-3/5/7s, I focused  mostly on the 1954-64 period, since that seems to more than  cover the period of any retrofitting. For passenger F-9s, I  looked at all of them, again to cover their entire NP  service lives.    Individual units are listed, along with the model type and  month/year of the image. A "YES" means that there is most  definitely a cooling coil on the left side of the roof fans.  a "NO" means that there definitely isn't. Again, the angles  of the views, unless noted otherwise, are good enough to be  certain of the matter. For freight units, I've grouped them  by model, but watch out for the passenger units, for  different models are mixed into same-number series groups,  as they are more difficult to break out. Here's what I  found:    FREIGHT UNITS:  6000A F-3A 8/65 NO  6000D F-3A 8/67 NO  6001A F-3A 8/62 NO  6002B F-3B 7/65 NO  6003A F-3A 7/65 NO  6003B F-3B 10/66 NO  6003D F-3A 8/68 NO  6004A F-3A 8/62 NO  6004B F-3B 8/67 NO  6004C F-3B 8/62 NO  6005C F-3B 8/65 YES (former Pass 6503C (1st); Frt  6016C (1st) 1948; Frt 6005C (2nd) 1950)    6005A F-5A 7/54 NO  6005A F-5A 8/62 NO  6051A F-5A 3/67 NO (ex-6006A)  6052A F-5A 6/68 NO (ex-6006D)    6010A F-7A 9/67 NO  6010C F-7B 7/65 NO  6011A F-7A 8/69 NO  6011D F-7A 8/61 NO (Note: This unit wrecked in 9/54,  reblt. 10/54 - 2/55, re-entered service with same number,  but some minor differences on unit; still no coil, however)  6012A F-7A 8/62 NO  6013D F-7A 6/70 NO  6014D F-7A 8/68 NO  6015A F-7A 2/70 NO  6015D F-7A 2/70 NO  6017A F-7A 8/68 NO  6017D F-7A 7/65 NO  6018D F-7A 8/67 NO  6019A F-7A 8/67 NO  6019C F-7B 8/70 NO  6019D F-7B 6/68 NO  6020D F-7B 6/68 NO  6050 F-7B 7/68 NO (Note: this was 6050B, but the  large-size B suffix was never put on the rear flanks)    Freight F-9As and F-9Bs in 7000 series: YES I have photos  of most in the fleet, 1954-70, too many to list  individually. Every pic showing left side roof shows the  cooling coils. This includes the two F-9As that were  originally passenger units: 7051A (formerly 6703A (1st)) and  7052A (ex- 6704A 91st)). It is most likely that these units  were delivered with the coils or had them added by NP upon  delivery from EMD.    PASSENGER UNITS:  6500A F-3A 5/63 YES  6501C F-7A 7/61 NO  6502A F-3A 10/48 NO  6502B F-3B 10/48 NO  6502A F-3A 7/66 YES  6504C F-5A 4/62 NO  6505A F-3A 9/65 YES  6506A F-3A 4/66 YES  6506C F-5A 4/61 NO  6506C F-5A 6/66 YES (this is the only image on these  lists that I have not just looked at, but am including it  here account it being so vivid)  6507A F-7A 8/59 YES  6507B F-3B 4/58 YES  6507C F-7A 7/65 YES  6508A F-7A 7/57 NO  6508A F-7A 12/61 NO  6508A F-7A 3/62 PROBABLY (this image shows the unit very  heavily damaged, just after being pulled from Granite Lake  following a derailment of train 25. The damage is so great  that the presence of cooling piping is in question, but I  believe it is there.)  6508C F-7A 7/66 YES  6509B F-3B 10/65 NO  6509C F-7A 5/67 NO (angle is a little low, so there  might be a coil, but I don't think so)  6509C F-7A 7/69 NO (angle is high enough here to be  certain--no coil)  6510A F-7A 8/62 YES  6510B F-7B 8/62 NO  6510B F-7B 9/68 NO  6511A F-7A 5/56 NO  6511B F-7B 5/56 NO  6511B F-7B 7/66 NO  6511C F-7A 6/52 NO  6511C F-7A 2/58 NO  6511C F-7A 7/65 YES  6512A F-7A 8/62 YES  6512C F-7A 6/61 YES  6512C F-7A 7/65 YES  6513A F-7A 10/54 NO  6513A F-7A 3/61 YES  6513C F-7A 7/65 YES    6551B F-3B 5/63 YES (ex- 6505B (1st); then 6017B (1st)  11/48; 6006B (2nd) 1/50; 6551B 1959)  6553B F-3B 4/66 YES (ex- 6504B (1st); then 6016B (1st)  11/48; 6005B (2nd) 1/50; 6553B 1962)    6600 FP-7A 6/66 NO  6601 FP-7A 9/60 NO      6700s F-9A and F-9B units. Every one appears to have had  the cooling coil for its entire NP life, including all  former freight F-9s that were converted to passenger service  during the 1964-67 period (there were several). I.e.,  conversion from freight to passenger was not a factor.    Judging from the above image list, the passenger F-3/5/7  conversion seems to be mostly (but not exclusively) on  A-units, and took place during the period, roughly,  1958-1963. The only significant thing that happened to NP's  passenger F-unit fleet during that period having to do with  the brake system, that I know of, was the discontinuance of  the electro-pneumatic brake system in May 1962, and the  consequent removal of all its parts by June 1964. These  dates don't match the retrofit period suggested above, nor  can I think of a reason for the removal of the  electro-pneumatic system having anything to do with this  cooling coil. Assuming that the coil was, indeed, associated  with cooling compressed air, I would guess that NP simply  tried to improve cooling on many units, but not on all of  them. As is often the case with such matters, limited  funding was probably a factor.    One other thing regarding passenger service and brake  systems: NP operated its passenger trains with 90 P.S.I.  brake pipe pressure, and its freight trains with 70 P.S.I.  Each of these figures was 20 P.S.I. greater for service in  mountain grade territory. The brake pipe pressure nominal  value was determined by the locomotive engineer, who would  set his feed valve in the cab accordingly. This may have had  something to do with the coil, but that is doubtful, as  there are too many inconsistencies in the above listings to  draw a relationship between coil and brake pipe pressures.    Bill Kuebler    PS: This took me a while! Anybody out there who wishes to  take some time to reciprocate and to, say, post some images  or something like that, please do. Especially images showing  this roof coil feature!    F3, F7, F9,  Compiler  C Frissell

01/20/03 22:24

Chris Frissell

For those of you interested in the minutiae of NP diesel history, I  have spent some time adding to Bill Kuebler's list of the occurrence  of rooftop cooling coils on NP F units. Bill posted his list last  year here based on his personal photo collection, and I have added to  it with records from published photos in the NP books I have  available. I started on this a while back, but was waiting for the  Dale Sanders NP book to some out before finishing a first cut at a  comprehensive list. For those few who are into this, here is link to  the document with the complete list, which I have posted in the Files  section of the NPTelltale Group. I will also copy the description and  summary from that document below so you can get the gist of the list:     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ROOFTOP COOLING COILS ON NORTHERN PACIFIC F UNITS AS OBSERVED ON  HISTORIC PHOTORAPHS  How the List was Compiled  This list is a working record of historical documentation of the  occurrence of rooftop cooling coil appliances on the EMD F-units of  Northern Pacific Railway. Un-cited entries in plain text are Bill  Kuebler's, from his photo collection and recollection. Entries in  italics are Chris Frissell?s additions from published photo sources,  as cited. The table lists engine number, model, date of photograph,  YES for rooftop coils definitely present, NO for rooftop coils  definitely absent, and notes, with sources and (for most records) page  numbers cited in parentheses as noted above. Full citations for the  published sources are given at the end of the document.     The following criteria were used to screen published photos:   Photograph should show a clear view of the fireman's side of the roof,  where the cooling coils are installed, if present. Engine number  should be clearly evident on the photo, or else positively documented  in the photo legend and verifiable by engine type, paint, and service.  Date at least to year is provided in the photo legend. Photos that,  based on month of image and engine number, were likely redundant with  Kuebler's photo records are not listed.     As Kuebler notes, all F-9s delivered from EMD, both freight and  passenger units, appear to have been equipped with rooftop coils upon  entering NP service. Therefore this list only records observations  of earlier-model F units, in order to help establish the history of  retrofits of these earlier models, none of which were originally  delivered with the rooftop coil appliance.     Please submit additional entries, corrections or suggestions via the  NPTelltale Yahoo Group, or directly via e-mail to Chris Frissell,  hanfris@d...     Summary    The list presents data on about 38 freight units and an equal number  of passenger units for which good documentation is available.   Multiple records for some units allow a rough reconstruction their  history. Allowing for gaps and making some extrapolation, it appears  that many F-3, -5, and -7 units in passenger service were retrofitted  with rooftop coils between about 1958 and 1963, and possibly some a  year or two earlier (the F-9 units were acquired from EMD in 1954-56,  so by 1958 the NP crews and shops would have had several years of  experience with coil-equipped units). Units dedicated to freight  service were not retrofitted. The single observed exception to this  rule, F-3B No. 6005C, was swapped between freight and passenger use  over the years, and while in freight colors also retained steam  generator vents on her rear roof panel.     With one possible exception, units that gained rooftop coils  apparently retained them for their service life. The possible  exception is passenger F-7A 6513C, which was reported by Kuebler from  his records to show a coil in 1965, but does not have a coil in two  clear published images from 1967.     The NP did not retrofit all passenger units with coils, but did most  of them. By 1965, for the passenger units having sufficient data in  this list, 5 F-7s and one F-3B did not have rooftop coils, in  comparison to 21 F-3s, -5s, and -7s known from the record to have been  retrofitted by that year. It is unknown why some units were not  retrofitted with rooftop coils and others were, but it seems plausible  that this was simply a consequence of shop scheduling for major  overhauls, coupled with a decreasing demand for passenger power in the  late 1960s that might have diminished the benefit to the railroad of  upgrading older units. By 1965 the NP had begun to trade in older  passenger units to GE and EMD toward their purchases of  second-generation freight power.     Although this is only a partial survey of published and Kuebler's  collected photos of the Northern Pacific Railway's F-3, -5 and -7  diesels, it is interesting to note there is much of variation in the  frequency with which individual units appear in photographs. The  most-often-photographed freight unit on this list was F-5A No. 6005A  (caught in four rooftop coil exposures). Passenger units on average  appear to be more popular, or perhaps less shy, with F-7As No. 6513A  and 6512C each showing in five separate rooftop coil poses.  F3, F7, F9, Compiler  C Frissell

01/23/03 17:48

Bill Kuebler

I  have spent some time adding to Bill Kuebler's list of the  > occurrence  > of rooftop cooling coils on NP F units.    After glancing over this file, I see one item that needs a  slight correction. Regarding passenger F-7A 6500C, your note  says that after its wreck in 8/55, it was rebuilt to F-9  6703C. Actually, the original number, 6500C, was retained on  the "new" F-9A from early 1956 until 1965, when the unit was  finally renumbered 6703C to integrate it into the 6700  series. As far as I know, the number was the only thing that  changed on that unit in 1965. During 1956-65, the 6500C was  the only F-9A in the 6500 series. Long story about this, but  for now you might want to note that number change in the  document so as to avoid any confusion.  F3, F7, F9, Compiler  C Frissell