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.}
