Tuesday, October 25, 2011

Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 2

In our last installment, we looked at the history of diesel-hydraulic road locomotive development in Germany. We noted the early development of twin-engined diesel-hydraulic road locomotives as early as 1953 by a consortium of German locomotive and engine builders and the DB itself; one of these early V200 locomotives is shown below from the Henschel Locomotive Engineer's Manual (pub. 1960.)

Design work progressed in high speed, light weight locomotive engines in Germany such that by 1959-1960 instead of 800 to 1100 HP V-12 engines, there were now V-16 engines capable of anywhere from 1600 to 2000 HP and transmissions which were capable of taking at least 1800 HP input by 1959. We will now move on to the ML4000C'C' as built for the US railroads - in this case, our data will be specific to the three units produced for the D&RGW railway.

Two further volumes will be consulted, whose covers are shown below.

These manuals are the Parts Manual for the ML4000C'C' locomotive, and the Diesel Engine Maintenance Manual for the ML4000C'C'.

Below is an overall external view of the locomotive as delivered from the factory. Remember to click any photos on this site to enlarge them.

Of course, one unit is shown, but it should be remembered that the original operation on the D&RGW for these units involved always using all three units in multiple, frequently with a dynamometer car. The intention was that three K-M units could replace the regular sets of EMD units D&RGW was using to haul trains, which normally amounted to six or seven units each rated 1500 or 1750 HP for traction.

Below we see an illustration from the parts manual showing the layout of equipment in the locomotive. Note that the engine compartments are leading, or are toward No. 1 end, from the radiator compartments but that the forward diesel engine's orientation is opposite that of the after engine because the Voith hydraulic transmissions are toward the ends of the locomotive.

Notable features in this illustration are the high mounted cab floor, raised over the high speed drive shaft for No. 1 powerplant; the compact diesel engines, each with two turbochargers mounted directly on top of the engine; the large Voith transmissions; and the cardan shafts (shafts with splines and universal joints) used to make the connections to drive the axles. Below, a diagram showing just the drive line components from the same manual.

The Dynastarter is both generator and starter motor; it starts the diesel engine through the high speed shaft (4) and thereafter functions as a generator for on board power and battery charging. The shafting is very obvious in this view, from engine to transmission, then to an intermediate gearbox, and finally to the axle drives.

The trucks and suspension on these locomotives are peculiar, largely because the mechanical equipment just described makes conventional center-pivot U.S. style trucks impossible. For this reason, K-M had developed a fairly complicated truck and suspension design for the V200, then for the six axle ML2200 / ML3000 and finally further for the ML4000 locomotive. Below, views of the truck construction and suspension arrangements.

Our final view is a cut showing the rear cab wall and the side cab view to give a complete idea of what the cab arrangement internally was like.

In our next and final installment on these locomotives, we will cover design details of the diesel engines, and discuss authoritatively the actual power ratings of these locomotives.


  1. Re: British Rail Diesel hydraulic Locomotives, pt. 1

    I don't know much about German diesel locomotives, but I thought it would be interesting to compare the German designs (described in the previous post) and the ML4000 to British Rail's diesel hydraulic types, most of which look as if they are adaptations of German designs, built in Britain but often with (license-built) German engines and transmissions. I have a fair bit to say, so will break this into (I think) 3 parts. This covers source, generalities, and a minor type that may not have been of german inspiration.

    Source: My main source is "BR Motive Power since 1948" by B.K. Cooper (London: Ian Allen, 1985). This is, I'm afraid, "railfan literature," but of the British genre that often seems rather more scholarly than most U.S. railfan stuff. If I had to compare this book to one U.S. locomotive book, I guess it would be to the "Diesel Spotter's Guide" or one of its successors, but (i) it has more extensive historical narrative, (ii) drawings (side elevation) with some dimensions and (iii) information about weight per axle which the American books often lack.

    Generalities: British rail, in the 1950s and 1960s, acquired some 385 diesel hydraulic locomotives, in eight different classes, all but one of which are closely comparable to German types described earlier. (This makes British Rail's experience perhaps the best "experiment" performed to compare Diesel-Hydraulic to Diesel-Electric locomotives. BR's hydraulics were a minority of their total fleet, but a sizeable one,and most classes seem to have been assigned primarily to the Western Region (roughly the pre-nationalization Great Western Railway), which means they would have been maintained and operated by staff familiar with them. (And many of BR's early diesel electrics were unimpressive, so it should have been easier for the diesel hydraulics to impress railwaymen in Britain than it would have been in the U.S.!) BR's later decision to standardize on diesel electric locomotives doubtless had many factors, but it certainly doesn't look as if the "experiment" showed the diesel hydraulics to be markedly superior to DE types!

    Minor class: There were 20 small four-wheel switchers in Class 2. These weighed about 30 tons, had 179hp Rolls-Royce engines, and might (for all I know) have owed as much to, say, Plymouth's diesel-torque-converter industrial switchers as to German developments. Cooper's book gives only summary coverage of small switchers. (British rolling stock is smaller and lighter than American, and BR's switching locomotives were all very low-powered by American standards, but these were small even by BR's standards.)

    To be continued with accounts of classes resembling German types.

  2. British Rail Diesel Hydraulic Locomotives, pt. 2

    Now for some with some clear German design influence.

    Class 14: Perhaps the least successful: 56 built, starting in 1964 (so: when diesel hydraulic technology was mature and well-understood), the last retired (by BR: some went on to lengthy careers as industrial switchers) in 1969. This is pathetic, even by the standards of the BR "Modernization Plan" and its unfortunate locomotive designs. It's not clear, however, that this short career is a consequence of bad design. The Class 14 was a 650 hp (engine hp) unit for switching and short-trip working, and BR in general was happy to use 350 hp units in such service. Three classes of diesel electric in the 800-900 hp range (Class 15, 44 units, Class 16, 10 units, and class 17, 117 units) were also all retired by 1971. So perhaps the Class 14 just didn't have a niche to fill, given the way BR's service requirements were evolving.

    Technical: the engine was British (Paxman Ventura 6YJX), but the Class 14 had a German transmission: Voith L217U, apparently built under license in Britain, with "two torque convertors and a fluid coupling. The torque convertors operated in the lower speed range. For full speed the drive was direct through the fluid coupling. The transmission was coupled by a second cardan shaft to a triple-reduction and reverse gearbox with jackshaft output." The locomotive was of a six-wheel rigid-frame design, with the wheels side-rod connected. The off-center cab carbody was clearly a British design, owing nothing to German styling, but the general configuration seems similar to German switchers stemming from the V-60. Total weight, 50 long tons (55.5 U.S. tons).

    (I think I'll do this in more parts than I originally planned: roughly one per type.)

  3. British Rail Diesel Hydraulic Locomotives, pt. 3

    Now for the direct analogues of the V200.

    The prototype V200 units (later class 220) were built in 1953 and 1954, but production didn't start until 1956 (acc. to Wikipedia). So there must have been at most a very small number in service when the Western Region of British Rail persuaded top management to let them buy a derivative.

    Initially, five prototypes (D600-D604; later Class 41) were ordered from the North British Locomotive Company (of Glasgow: an established steam builder). The MAN engine (L12V18/21A) and Voith transmission (L306r) were chosen; North British has obtained licenses and engines and transmisions for three of the five were built by NBL. The carbody, however, was totally British: 65 feet long, A1A trucks (with the center, idler, sheels smaller in diameter than the drivers), and HEAVY: the locomotive weighed over 117 long tons (so: ca. 129 short tons), almost one and a half times what the German original weighed, but with only 80 long tons on the drivers. Big "selling point" of the diesel hydraulic was that it had lower weight than a diesel electric of comparable output, and this advantage was given away by over-conservative design of "locomotive mechanical portion"! This seems ... unfortunate, particuloarly since Western Region wanted a light-weight locomotive for its hilly routes.

    First unit built January 1958, last retired December 1967.


    Meanwhile, somebody at Western Region seems to have realized that something better could be done... A more thorough adoption of German design, including a carbody based on the V200 (complete with slightly bulbous noses, a feature unique to this series on BR), shrunk to fit the restrictive British loading gauge, allowed the next series of V200 derivatives to weigh a mere 78 (long) tons. 37 units, later designated Class 42, were built at the former Great Western Railway shops at Swindon, the first in August 1958. These had the 12-cylinder Maybach MD650 engine (in, except for the first three units, the up-rated 1,135hp version used in the German V200.1 series (later class 221) locomotives), and the Mekydro K104 transmission. A 38th was built to try out a British-design engine of similar size and power, the Paxman 12YJX of 1,200 hp.

    The last of these Swindon-built units was retired in December 1972.

    North British was also induced to use the lighter body, and, starting in July 1960, built 33 units later classed as Class 43. These has the MAN L12V18/21B engine (i.e. same as before, but now uprated to the 1,100 hp that would have been used in a German V200.1) and the "Voith-NBL LT306r" transmission. The last was retired in October 1971.

    British Rail gave names as well as numbers to many of its bigger locomotives. Units of Classes 41, 42 and 43 were (with one exception) given names of Royal Navy ships, and are known to British railfans as "Warship" units.

    The Swindon-built Class 42 seems to have lasted a bit longer than the NBL-built Class 43. This MIGHT reflect problems with the MAN engine, but NBL went bankrupt in 1962, so Class 43 lacked manufacturer support for most of their careers.

  4. British Rail Diesel Hydraulic Locomotives, pt. 4

    A single-engined type.

    The bigger diesel-hydraulic locomotives of the 1950s and 1960s -- like the V200 and its British derivative-- tended to be twin-engine designs. Obvious thought: put half the works on a platform for a lighter-duty locomotive. North British, the MAN licensee and originator of the first attempt (Class 41)at a British V200, tried.

    Class 22 was a B-B unit with a general carboy styling similar to Class 41, with a single MAN 12 cylinder engine (rated at 1000hpin the first si, 1100 hp in the rest) and aVoith-NBL L306r transmission. It was shorter (46'8.5" as opposed to 65' over the buffers)and lighter (68 long tons against 117) than the Class 41, and was one of ten classes of twin-cab "mixed traffic" locomotives in the 1100-1250 hp range ordered by British Rail. The first unit out of 58, was built in January 1959, and the last retired in January 1972: not an impressive lifespan.

    There seems to have been a deliberate effort on the part of British Rail to perform a controlled experiment, comparing diesel-hydraulic and diesel electric designs, with this class. North-British also built 58 diesel electrics, in a very similar carboy, of Class 21, starting in December 1958. These had the same MAN engine as the Class 22 (rated 1000hp in the first ten units, 1100 hp in the rest). The comparison does confirm that diesel hydraulics tend to be lighter than diesel electrics: Class 21 was about 4 long tons heavier and five feet longer than Class 22. As for how well they did in service... the last "straight" Class 21 was retired in August, 1968. But 20 of the diesel-electric Class 21 (and none of the diesel-hydraulicClass 22) were chosen for a re-engining project, getting 1350 hp Paxman 12YJXL engines, and the last of these lasted until December 1971.

    None of these units seem to have been spectacularly good technically, but I suspect the main reason for their early retirement was that BR found it had a declining need for locomotives in this power range, and got rid of minority brands: they had 228 1000 hp unit in Class 20 (*) and over 500 1160 hp to 1250 hp units in the three, very similar, Classes 24, 25, and 26 (**).

    (*) unusually, for British "road" units, a hood design with a single cab: looks to an American like a badly squashed Fairbanks-Morse switcher! Diesel-electric, with an English Electric 8SVT engine.

    (**) typically British in appearance: full-width carboy with two cabs. All powered by Sulzer 6LDA28-A and 6LDA28-B engines, but with different makes of electrical gear.

  5. British Rail Diesel Hydraulic Locomotives, pt.5

    A more successful (?) single-engined type.

    Class 35 (nicknamed the "Hymek") was another twin-cab "mixed traffic" locomotive design, this time from Beyer Peacock (another old-line steam locomotive builder), this time in the [1500 hp,2000 hp) "Type 3" power interval. These had 16 cylinder Maybach MD870 engines rated at 1740 hp, and "Stone-Maybach" (I assume, though haven't verified, that Stone was the British licensee for the Maybach design) "Mekydro" transmission. It wasn't a direct derivative of a German design, but seems roughly equivalent to the "V160."

    101 units were built,the first in May 1961; the last was retired in March 1975. My impression, from miscellaneous reading and conversation, is that they were thought of as one of the better diesel-hydraulic designs, used on both passenger and freight trains. Again, their relatively short lives may have been due to a desire to rationalize maintenance by eliminating minority types: in their power range, BR had 98 Sulzer-engined Class 33 units of 1550 hp and 308 English Electric Class 37 units of 1750 hp, both the English Electric and Sulzer engines being used in numerous large classes of diesel-electrics.

    These units are interesting from an American perspective because the engine is the same as that used (in pairs) in the MK4000, though in the BR application it has a lower rated horsepower and operated at 1500 rpm instead of the 1600 used in the "Amilok". (British Rail seems to have liked conservative engine ratings: the English Electric 12CSVTrated 1750 hp in the Class 37 had, I think, already been used at a 2000 hp rating in an export locomotive.)

    (One more BR d-h class to go: I hope the Davis brothers think my reports on British types are an interesting supplement to their discussion of the MK4000 and its German antecedents!)

  6. British Rail Diesel-Hydraulic Locomotivs, pt. 6

    A V3000 analogue?

    The final BR d-h for heavy mainline service (both express passenger and heavy freight) was the Class 52. (Nickname: Westerns. These units were given two-word names, the first word in each case being "Western": recall that BR d-h types were used primarily by the Western Region, which was for the most part the successor to the pre-nationalization Great Western Railway.)

    This was a CC unit, 68 feet long and weighing 108 (long) tons. Carbody structure similar to the German-derived Classes 42 and 43, but with a different-- unique-- cab styling. Power was two MD655 12-cylinderr engines, rated at 1350 hp. (This was very similar to the MD650 used in the Class 42, but intercooled and so more powerful.) Transmission was the Voith-NBL L630rV.

    First unit (of 74) built December 1961; last retired February 1977. (Class 50 diesel electrics of about the same power were cascaded to the Western Region after the West Coast main Line electrification was completed to Scotland, and by 1977 the HST trains were beginning to be used on Western Region. So it was probably inevitable that SOME class of diesel locomotives would be phased out. Evidently BR management thought the d-e Class 50 was a better bet for the future than the d-h class 52.

    Interestingly, we have another "controlled experiment" on electric versus hydraulic transmission. In September 1961 Brush Electrical Engineering (one of the major players in supplying diesel locomotives for BR) built a d-e demonstrator, the "Falcon," powered by two MD655 engines rated at 1400 hp each. This locomotive was slightly heavier -- 115 long tons -- and ten inches longer than a Class 52. It was evidently quite successful: even though it was a unique unit (BR having decided to buy Class 47 units from Brush instead: slightly less powerful, with a single Sulzer engine instead of two MD655), BR bought it, assigned it Class 53, and ultimately assigned it to the Western Region, where the MD655 engine was familiar: it was used, like the Class 52 units, both on express passenger trains and other duties suitable for a locomotive of its power.

    Concluding note: The often-quoted dictum that diesel hydraulics are lighter in weight than diesel electrics of similar power doesn't seem to be born out by BR's types. The 2700 hp d-h Class 52, with two light-weight, high speed, diesels, weighed 108 tons. In the 1960s BR also acquired two classes of diesel electric of about the same horsepower, but using Sulzer or English Electric medium speed diesels that were heavier, for their output, than the medium speed diesels used by EMD and Alco. The Sulzer engined Class 47 -- originally rated at 2750 hp, though later derated to 2580 -- weighed from 111 to 125 tons (over 500 were built, and they came with different options), and the English Electric powered Class 50, of 2700 hp, weighed 115 tons. But the Class 50 was heavier than it had to be: English Electric's prototype for the class, the demonstrator DP-2 of 1962, using the same engine, weighed only 105 tons. Suggesting that a well-designed diesel electric might outweigh a comparable diesel hydraulic by only 2%, despite using a much heavier prime mover!

  7. Hello,

    Thanks for your web-site - unfortunately I discovered a bit too late for building my model(s) (DRGW's KM in 1" scale and the BLW gas-turbine in 1/2" scale). Seems to be that we share the same preference of locomotive types.
    My blog on building these models:

    However, your construction plan of the KM's side frames will help me a lot finishing that parts.

    Best regards

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