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Locomotive Performance and Tractive Effort Discussion

Discussion in 'Steam Traction' started by MellishR, Nov 26, 2022.

  1. johnofwessex

    johnofwessex Resident of Nat Pres

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    So of Chapelon was working on 'Post War' rebuilding projects during WW2 it was a good way of doing nothing of any immediate value to either Vichy or The Germans
     
  2. RAB3L

    RAB3L Member

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    Marc de Caso's 232U1 in Mulhouse:

    232U1.jpg

    https://en.wikipedia.org/wiki/SNCF_232.U.1

    https://fr.wikipedia.org/wiki/232_U_1

    Whilst many French compounds had two regulators (both used when working the loco as a simple, and just one used in compound operation) and two sets of reversing gear, 232U1 had one regulator and one reverser. At cut-offs longer than 55% the locomotive worked as a simple, at shorter cut-offs the locomotive automatically operated in compound mode. On test in 1950 232U1 was recorded producing 3265 drawbar horsepower over an 8km section.
     
    Last edited: Dec 10, 2022
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  3. Hunslet589

    Hunslet589 New Member

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  4. Eightpot

    Eightpot Resident of Nat Pres Friend

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  5. RAB3L

    RAB3L Member

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    Here (from Martyn Bane's site):

    232U1 LHS.jpg

    The vertical bar or pipe? It doesn't seem to be there on the other side.

    232U1 RHS.jpg
     
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  6. RAB3L

    RAB3L Member

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    Chapelon Pacific Nord 3.1192, later 231E22, at Mulhouse courtesy of Martyn Bane's website:

    231E22.jpg

    The first 20 of the class were rebuilds of PO 3700 Class and were built in 1934. A further 28 were built new between 1936 and 1938, so it is not true that Chapelon was not responsible for any new locomotives.

    These Pacifics were of the De Glehn Du Bousquet four-cylinder compound system, with the high-pressure cylinders positioned externally. Timing was of the independent Walschaerts type with four-cylinder "Lentz-Dabeg" oscillating cam valves, offering very large steam passage sections.

    231E22(2).jpg

    Starting devices consisting of two "rotating skylights" allowing during the starting phases to admit high pressure steam to the low pressure cylinders, and to direct the steam having worked in the high pressure cylinders directly to the exhaust.
    The Belpaire firebox featured a Nicholson siphon and a semi-overhanging trapezoidal grate firebox. The exhaust was of the double Kylchap 1K/1C type and the boiler was supplied with water by two injectors and an ACFI type water heater feed assembly.

    These locomotives hauled La Flèche d'Or between Paris and Calais until 1967 and could provide 2700hp sustained. There was no mechanical stoker! Along with 232U1, these are the stars of Mulhouse. 231E41 is under restoration to working order in Tours.
     
    Last edited: Dec 12, 2022
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  7. RAB3L

    RAB3L Member

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    A model at Mulhouse of Chapelon's 240P:

    240P.jpg

    These were rebuilds of PO Pacifics of the 4500 Class. Built by 1940 to tackle the Les Laumes to Dijon division of the line from Paris to Lyon. They could sustain over 3000hp at the drawbar. These locomotives had the highest power to weight ratio of any steam locomotive until Porta's "La Argentina" of 1948. In full size it would have been THE star of Mulhouse.

    Despite repeated requests from the traction services of the North and West regions, to which the general management of the SNCF categorically refused to respond, despite the significant needs of these two regions in terms of powerful and versatile traction equipment, these machines were canceled for part in October 1952 and for the other part in November 1953, this no doubt due to the new orientations of the SNCF in terms of traction, namely the abandonment of steam in favor of electric and diesel traction.
     
    Last edited: Dec 12, 2022
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  8. Eightpot

    Eightpot Resident of Nat Pres Friend

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    One needs to look closer as they are black and in the background.
     
  9. RAB3L

    RAB3L Member

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    Chapelon's 160A1:

    4-160A1.jpg

    Converted from a 150A between 1938 and 1940 in Tours. Built to allow the haulage of 1,200 tons up a 1:100 incline at 30kmh. There were six cylinders, two external LP cylinders in the front driving the third axle, two internal LP cylinders at the front driving the second axle and two internal HP cylinders driving the fourth axle. There was reheating between HP and LP cylinders. On the first, fifth and sixth driving axles there were lateral displacement devices because of the long wheelbase. Valve gear was Walschaerts driving Lenz poppet valves.

    The boiler was divided into two sections, with the front two meters (78 3/4") housing the pre-heater. A Houlet superheater with 72 sq m ( 775 sq ft) of surface served the HP cylinders while a modified Schmidt Type A (110.46 sq m/1,189 sq ft) supported the LP cylinders. The Schimdt four-element heater was actually laid out as two parallel sets of two series circuits.

    In June 1940, the locomotive left Tours with a 1200 ton train bound for Brive, without any previous running-in. It was secreted there during the war from the Germans in the Brive depot - no collaboration there! Despite very satisfactory performances, and like many unique machines, it saw little service. She was withdrawn on October 28 1954 after having traveled only 40,000 km and, like the 242A1, was cut up very quickly too, in March 1955 at the Châteauroux depot.

    A model (full size?) of 160A1's LP cylinders in Mulhouse:

    160A1 LP Cylinders.jpg

    4-160A1_2.jpg

    Two lower photos courtesy of Martyn Bane's website.

    Incidentally a 150A, 150A65 was originally planned to be displayed at Mulhouse but this was abandoned due to the poor state of the tender due to years of external storage. The externlly restored locomotive is now on display by a roundabout in Perigueux with a replica tender.
     

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    Last edited: Dec 12, 2022
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  10. Steve

    Steve Resident of Nat Pres Friend

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    Was that triple expansion? If the cylinder block shown represents the low pressure cylinders then the inner and outer ones appear to be different diameters.
     
  11. Flying Phil

    Flying Phil Part of the furniture

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    Whilst fascinating to see such French steam developments, why are they in the "Sir Nigel Gresley" thread? Surely they deserve their own thread.
     
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  12. 35B

    35B Nat Pres stalwart

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    Which statements take us in to the discusssion about who and what Chapelon was.
     
  13. 30567

    30567 Part of the furniture Friend

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    Vitry sur Seine

    https://www.nature.com/articles/132308c0
     
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  14. 35B

    35B Nat Pres stalwart

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    I'm far from convinced, and unsure how to rank him, whether with the Gresleys, Staniers, et al; with the Portas and Wardales on another, or the Pagets and Fells on a third.

    My problem is that, based on this discussion, it's nigh on impossible to tell what Chapelon's engineering excellence achieved, or how it could have been put into practice. I know too little about French railways and their history to understand how the roles of senior engineers compared, or how his failure to ascend to the highest levels reflects on his ability. We know that Chapelon had the keys to the test centre at Vitry, so was obviously a serious figure within French railway engineering. Yet he created few designs, and they were little more than prototypes, never really fully tested for their in traffic potential.

    I then reflect on the discussions about Gresley and Thompson, what they achieved, and against what challenges. They raise important questions about what a good CME was, and how we judge the calibre of an engineer.

    Ultimately, I can only conclude that no meaningful comparison between Chapelon and any CME, Gresley or otherwise, is viable. They simply did such different roles that meaningful comparison is impossible. We can infer what might have been possible had Chapelon's designs made it to mass production and widespread service, but those conclusions can only be speculative.

    Ultimately, the counterfactual comparison that comes to mind is with Oliver Bulleid, if we imagine that he had not left the LNER but remained as a senior member of the CME's staff. We have insights into his creativity from his time at the LNER, but nothing on which to really judge his capabilities. We can infer, but no more, what might have been.
     
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  15. Eightpot

    Eightpot Resident of Nat Pres Friend

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    It looks like 160.A.1 was fitted with Lentz(?) oscillating cam poppet valves, hence the two valve bores per cylinder.
     
  16. RAB3L

    RAB3L Member

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    Vitry.
     
  17. RAB3L

    RAB3L Member

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    No, but triple expansion was considered. Outer were 640mm and inner 520mm dia.
     
  18. RAB3L

    RAB3L Member

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    Chapelon's designs were mass produced and some were new. The second batch of what are known as Chapelon's Pacifics (231E) were new and lasted from 1938 to 1967 -see above.

    https://fr-m-wikipedia-org.translat..._3.1198?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en
     
    Last edited: Dec 12, 2022
  19. RAB3L

    RAB3L Member

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    160A1 was designed and largely built before WW2. The electrification policy was decided upon and implemented after WW2. I'm not sure how that detracts from the achievement.
     
  20. 242A1

    242A1 Well-Known Member

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    160A1 is an interesting case. It was built as a six cylinder locomotive because it proved to be impossible to obtain sufficient low pressure cylinder volume within the limits of the French loading gauge. Though this introduced further level of complexity it was not without benefits and the dividing of the piston thrust loads was one of them and the reduction in weight of the individual sets of motion was welcome too. The incoming steam flowed around the cylinder walls and the heated walls helped to overcome the cooling effect inside the cylinders as the steam expanded, it helped to avoid condensation. The steam exhausted from the high pressure cylinders was superheated again before being used in the low pressure cylinders. The locomotive also included an adaptation of the work carried out by Dr Piero Crosti and Attilio Franco in that there was a third tubeplate some seven feet from the front tubeplate and the volume separated off served as a feedwater heater and this proved to work very well.

    It was also with this engine that Chapelon took steps to address the leakage problem. The locomotive was fitted with Lentz poppet valves of the oscillating cam type. The drive to these valves was taken from Walschaerts valve gear and this gear was to be found outside the frames in spite of there being four inside cylinders. The valves were different to those that had been fitted earlier in that they were given conical seats in order to overcome the leakage problems typically encountered with the use of poppet valves. With the original design, the valve and its associated seat were machined to to provide a seal and this was done at ambient temperature however thermal expansion and contraction in addition to temperature miss match brought about dimensional changes which in their turn brought about leakage. The decision to use the conical seats was made after trials with one of the 4-8-0s.

    This machine delivered some extraordinary results. It succeeded in delivering high power outputs at low speeds and fuel consumption continued to drop even when speeds became lower than 20 mph.
     
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