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.

Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 1

After a very long time on the RIP track, I've decided to haul our blog RAILROAD LOCOMOTIVES out of the weeds and place it back into service. Here's the first new run.


Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 1

I have been very fortunate recently to acquire some new material which describes the type ML4000C'C' diesel-hydraulic locomotives built by Krauss-Maffei of Munich, Germany and which were delivered to two U.S. railroads (Denver & Rio Grande Western, three units, and Southern Pacific, three units) in August 1961. While very much has been written and repeated about locomotive design in the United States up until the time that the arrangements were made to construct these units and the effect this had on the desire to increase unit horsepower, very little has been presented in the English language in a brief form to explain the background behind their development in Germany. Using the newly found materials, and a number of documents and magazine scans sent to me over six years ago by Steve Palmano, I'll try to fill in both some of the background information and some design details of these units.


Development in Germany prior to 1960

The earliest developments in hydraulic transmissions for use in diesel locomotives in Germany, prior to the war, did not result in anything which we would consider full capacity road locomotives here in the United States. After the war, the nationalized West German railway system, known as the Deutsche Bundesbahn or most often simply DB decided that it would eventually have to embark on either electrification (which was highly desired) or else dieselization and developed a series of specified design parameters for locomotives which were grouped into a designation system with "V" designators. For example, in this overall plan, there was to be a switching locomotive for very low speed service known as the V60 which would be rated roughly 600 horsepower - that is to say, the diesel engine installed would have a brake horsepower rating of 600. Below, a diagram of a V60 from our copy of the 1960 Henschel Locomotive Engineer's Manual showing external view and internal details.

In this view, the diesel engine is easily made out under the larger of the two hoods, with high speed drive shaft to the hydraulic transmission. The transmission then drives the jackshaft which is connected to the driving wheels by side rods just like steam locomotives or some electric locomotives.

Moving more toward our story, now, the DB made the move in 1951 to apply this kind of technology to a true road locomotive. Clearly, side rods were not permissible and so trucks would have to be used; also, a steam generator to heat passenger cars was desirable to give the locomotive dual service capability. The DB had also provided a specification for a new range of diesel engines to be used in diesel-hydraulic locomotives that spurred competition between engine makers because it clearly implied that large contracts for production engines might be in the offing. The specification did however push the envelope of existing engine technology because of the requirements for very high power to weight ratio and the statement of a required top running speed of 1500 RPM.

The result in 1951-1952 was the construction of ten V80 class prototype locomotives. Three different makes of diesel engine were used experimentally - these being Daimler-Benz's Mb820Ab, the M-A-N L12V 17.5/22B, and the Maybach MD650. All were high speed V-12 four stroke diesel engines with what in European circles is referred to as pressure charging by exhaust-driven turbosupercharger. We simply use the term "turbocharged." Although the engines were of similar size envelope, there were many construction detail differences and the fact was that the M-A-N engine was fairly bad in service while the other two were good. Below, a V80 locomotive photo from the Henschel manual.

In these locomotives, two different makes of hydraulic transmission were used; the Voith Turbo and the Maybach Mekhydro. The Voith was a complicated unit that used three different torque convertors which were emptied and filled automatically, giving a starting high-torque range and two running speed ranges. The Maybach unit used one torque convertor and four power shifted gears, like a large automobile transmission. On both, shifting was totally automatic; inputs to shift control were throttle position and track speed.

A number of detail problems were made quickly apparent by these units, most notably the tendency of the long intermediate drive shafts from the transmission (centrally mounted) to the two truck assemblies to twist under heavy load. In later units of this size and power range, the transmission was much lower and very short shafts used to the trucks in order to avoid this torque twisting.

The "type" program now evolved into two important types for road service - a V100 of about 1000 HP based on the V80, with improvements, and a large road locomotive of twice the power to be called V200. The V200 was the first large diesel-hydraulic road locomotive type in the world; these were built beginning in 1953 with several prototypes. Below, the V200.

The well publicized tour of one of the original units of this type over a large portion of Europe, sponsored by its builder, Krauss-Maffei, spurred the order for three locomotives of modified design for Yugoslavia. These units were slightly longer, had six axles instead of four, and had two 1100 HP engines. These were classed by Krauss-Maffei as its ML2200 type.

One further six-axle unit of this type was built in 1957 for testing in Germany. As the decade was moving to an end, there was a massive rush of locomotive development in Germany. At once, much higher powered engines and hydraulic transmissions capable of taking their output began to be developed, in part in response to the specification for a single-engine locomotive between the V100 and V200 in output. This would become the V160, first actually built in 1960. Below, a view of one of the first prototype V160 locomotives.

For this range of locomotive, both Maybach and Daimler-Benz had developed 16 cylinder high speed engines of 1600-2000 HP output range; Voith and Maybach were hard at work to produce transmissions which could handle the output.

The most important step in the development between the ML2200 and the ML4000 was the conversion of the single German ML2200 into the prototype ML3000 in 1959. This involved replacing the original MD650 engines with MD655 engines; these Maybach 12-cylinder engines were very much the same except that "charge air cooling" or intercooling was employed, with a higher boost pressure. The new engines were rated 1500 brake horsepower; new Maybach Mekhydro transmissions of type K184 were installed that could handle the increased output. The locomotive immediately proved very powerful and capable.

This locomotive (when completed in new form in the first quarter of 1958) was rated a total of 3000 brake horsepower, had a weight in working order, fully loaded of almost 114 short tons (a very high power to weight ratio,) a starting tractive effort at 30% adhesion of 65,800 lbs when 2/3 loaded, a continuous drawbar rating of 59,500 lbs at 12.3 MPH and a top speed of 87 MPH. This was probably the first diesel-hydraulic road locomotive that approached characteristics that could get the attention of U.S. railroads in a serious way. Krauss-Maffei continued its efforts to construct locomotives for export in addition to continuing to build "V" classification locomotives for the DB, and the stage was set for immediate development of the ML4000 by simple extrapolation.


Wednesday, January 5, 2011

Ingersoll-Rand 10" x 12" 300 HP Diesel Engine

Most historians and railfans are aware that the first commercially successful diesel-electric locomotives to be produced in the United States incorporated a diesel engine manufactured by Ingersoll-Rand, but have never seen that engine. Let's take a brief look at this design and how it was built.

For this article, we're using an Ingersoll-Rand maintenance manual for the photos and data, courtesy the David A. Davis collection. We think it may have been printed about 1935. At left is an overall view of the engine, which had the following characteristics: 10 inch bore and 12 inch stroke; idle speed 250-275 RPM depending upon auxiliary load; full speed 550 RPM at full load, and with light load full speed was 570-575 RPM. The engine was rated at 300 brake horsepower.

This diesel engine was developed by Ingersoll-Rand for use in locomotives - but in fact this diesel engine really bears no resemblance in any way to common diesel engines for locomotive service that appeared later. For example, the use of exposed push rods was common at the time (even in submarine diesels) and so it was carried over here; no doubt, the problems of dirt and dust in locomotive service weren't yet well appreciated. Note also the use of totally exposed cylinder units; these were a common thing in early, large gasoline, distillate and oil (otherwise known as Diesel) engines at the time as well but later engines of all builders enclosed the cylinders fully in the engine frame. (Item: The first to get back away from this was the Cooper-Bessemer FWL and later FDL series.)

The manual covers two models of engine, known as the 360C and 420C models. These differ mechanically in compression ratio; the model numbers used are actually references to the peak compression pressures for each model. Valve timing and injection timing also differ between the two models. The modest power output of these engines, given their displacement and speed, is more understandable when one reads tha the peak firing pressure of these engines was on the order of 500 to 550 pounds - so that for the 420C the firing pressure at the maximum limit was only 130 pounds higher than the compression pressure. One other change between models was minor- the location of the fuel transfer pump.

Let's take a look at a section drawing of the engine to begin to see some construction features.

This drawing was originally intended to show oil flow - which with the red lines we can see flows through the drilled crankshaft to the connecting rods and then to the pistons, finally draining from their undersides into the sump - but really shows other details quite well. Note at the right the large flange used to mount the main generator, and the flexible coupling inside of that. These engine-generator sets used spring loaded bolts to hold the sets to the I-beams in the center of the locomotives, helping ensure that road shock and frame flex were not transmitted to the set (and thus the crankshaft.) Note also the pent-roof pistons, commonly seen with the Price fuel injection system concept which we'll examine in a moment. Some cylinder head details are visible here; note the long studs going from the top of the heads all the way down into the cylinders. Note also that the heads make positive full contact between each other; the heads not only contain (enclose) passages that connect to one another forming intake and exhaust manifolds (with appropriate pipe connections at the ends of the engine) but also form an upper longitudinal strength member for the engine.

Here's a closer look at the cylinder head - and if we look closely we see that the head is actually mounted on top of a piece that is interposed between it and the cylinder unit. This piece is called the combustion chamber; thus, the head itself contains only the valves, rockers, injection nozzles and so forth and is mounted on top of a separate cylindrical but short piece that forms the combustion volume when the piston is at TDC. The two fuel injector nozzles pointing into the combustion chamber at 180 degrees from each other are typical of the Price injection system design. The small valve is for air starting the engine.

Here is the engine base, turned upside down. This is the main strength member of the engine; it mounts the main bearings and thus the crankshaft as well as the camshaft. The cam deck is visible on the bottom (remember that this view is upside down as in the manual) with holes for the push rods to pass through. The housing mounts on top of a base, which serves only to collect lube oil acting as a sump, and of course as a support.

At left, one of the cylinder units. Six studs are visible which are used to attach the cylinder head (with interposed combustion chamber.) Note the flange around the base of this unit, used to bolt it to the engine housing we just saw. The four identical openings on the cylinder itself are actually normally blanked clean-out openings; the small flanged connection visible here in the center near the lower end is the cooling water inlet. Since no cooling water comes in contact with the main engine frame, we can classify this engine as a "dry block" engine.

The manual only shows a few locomotives, and all of them shown were built after ALCO left the group and went off on its own. Here we see two locomotives; at the top, Illinois Central 9000, a 100 ton 600 horsepower twin-engine box cab locomotive, and below is Bush Terminal 2, a 60 ton 300 horsepower switcher style locomotive. It is interesting to note that while the box cab design went away in favor of locomotives with narrow hoods, the characteristics of the locomotives built to the upper twin-engine design - namely, weight in working order of 100 tons and horsepower of about 600 - were established by this design and remained in production and competitive until several years after the end of the Second World War, at which time the competitive situation drove the horsepower ratings of 100 ton switching locomotives above the 600/660 HP level to 750, 800 and even higher. In other words, the original rating of the 100 ton unit conceived by ALCO-GE-IR in the mid 1920's remained useful and competitive for about 20 more years.

Ingersoll-Rand attempted to remain in the locomotive field only briefly after its original engine became non-competitive. It built its Model S, with the same bore and stroke but overall new construction and much higher rating which failed to meet any wide industry acceptance, and apparently exited the market after 1936. We hope you've enjoyed this brief look at this truly pioneering diesel engine.

{First in a series on the design and construction of diesel engines for use in locomotives.}