Wednesday, December 8, 2010

"V" type EMC 201A Diesel Engines

Continuing with our theme of showing diesel engines either never shown anywhere before, or seen rarely, we now bring out (from the David A. Davis collection) EMC Bulletin 118A, with an issue date of February 1, 1941 and which is titled "Operation and Maintenance Instructions for 12-201A and 16-201A Diesel Engines for Railway Equipment." We won't reprint the whole huge thing here but instead we'll give somewhat of a general idea of the nature of these pioneering engines.

Our first illustration is an exterior view of the V-12 version of the 201A.

In this view the engine is sitting on top of some sort of base which appears not to have been for locomotive installation. The near end is the blower and auxiliary end; the far end is the generator end. Note that the water pumps are mounted on the end of the large blower housing, on top of which is the large cylindrical air cleaner; note also the housing at the opposite, or generator, end, for the timing chain and gears. The engine has one exhaust stack for each cylinder, and these can be seen sticking up at the center of the engine. The governor (Woodward SI) is in evidence on the near corner of the engine.

Next, the 16-201A - largest and most powerful of the 201 line.

Clearly evident on the 16-201A are the dual air cleaners, required because of the increase in volumetric flow rate of air. Otherwise, this engine is largely the same except for one very interesting fact: The block angle on the 12-201A was 60 degrees, but on the 16-201A the block angle was 67-1/2 degrees. Surely this was a requirement to balance the engine against torsional vibration. One further interesting difference between the 12 cylinder and 16 cylinder engines was that the 12 cylinder engine had a firing order in which pairs of cylinders fired simultaneously, but the firing order of the 16-201A was individual like you'd find in most other engines.

Basic specifications applicable to both engines are as follows:
BORE 8 inches
STROKE 10 inches
COMPRESSION RATIO 16 to 1
IDLE SPEED 250 RPM
FULL SPEED 750 RPM
CYLINDER DISPLACEMENT 502.65 cubic inches

RATED POWER OUTPUT 12-201A 900 HP / 16-201A 1200 HP

Here is an overhead diagram of the 12-201A engine. Notable immediately is the staggering of the cylinders, like you'd find in any four-stroke Vee engine. The 201A did not use fork and blade connecting rods, but rather side by side rods as was conventional practice which naturally dictates this arrangement. Note the blower housing on the bottom end of the illustration. Weight figures for the engines are given, although not indicated is whether they're wet or dry: 12-201A, 18,500 lbs; 16-201A, 22,100 lbs.





Here is a fascinating cross section view of the 12-201A. Notable are the flat bottomed cylinder heads; combustion space is in the piston crowns. The original one piece heads were at printing of this manual being replaced with "pot type" heads in which a removable insert containing the exhaust valves and injector nozzle was inserted into the head. This is exactly the kind of modification that General Electric would introduce many years later on its production U28 series locomotives incorporating the FDL-16C engine ("Steel Head / Single Pipe Manifold" variant, which there will be lots more about on this blog in the near future.) At print, the original pistons were being replaced with forged pistons (material is not specified) but the manual states that the difference in mass between the two styles was not enough that pistons could not randomly be refitted as needed to individual cylinders (although it was recommended to fit at least a whole bank at once.)

This brief overview should give all who are interested at least a basic idea of the arrangement and design of the pioneering 201A locomotive engines; we can answer more specific questions using the 'comments' feature on this blog if need be.

1 comment:

  1. I read your blog.I thought it was great.. Hope you have a great day. God bless.

    Rica
    www.imarksweb.org

    ReplyDelete