Art Deco Diesel – The Fairbanks-Morse 31A En bloc Series

aka Diesels that look like toasters, Part I. 

As we outlined in our very first post here, Fairbanks-Morse introduced a line of what they called “En bloc” engines, meaning whole, which to put bluntly, they used a one piece cast crankcase with integrated cam pocket and bearing bores, which F-M advertised as putting all of the pieces in perfect alignment every time.   Attached to the block would be the various auxiliary pumps, exhaust belt, water header, blower, etc.

VDD Post on the Fairbanks-Morse 31A18

The F-M 31A En bloc engine seems to have made its first appearances in advertising around 1945.  This specific line of 31A appears to be the decedent to the 31A “Borneo” engine.   The first real production of this 31A series seem to start around 1949, which is the publication dates of each of my manuals.   The 31A was offered in 3 bore sizes: 6 ¼”, 8 ½” and 18”.   

An 8 Cylinder 31A8 ½“, setup for stationary service – Note the Woodward UG8 governor control panel. FM Photo. Click for Larger

The 31A we will be discussing in this post is specifically the two smaller versions of the model, the 31A6 ¼” and the 31A8 ½“.  The engines are two stroke, cross flow scavenged, with an integrated scavenging blower, as well as an optional compressor, bilge pump and water pumps.   Both models were offered in a direct reversing marine model, or a stationary model, and in the case of the larger 31A8 ½“, a dual fuel version.  An additional option on the direct reversing marine engine, was a reduction gear with an Airflex clutch (note- this is not a reverse reduction gear, the engine is still direct drive).  Both models were available in either rotation.

31A6 ¼”: 6 ¼” bore, 9” stroke
Marine & Stationary Engines – 720RPM
5 Cylinder – 150HP
6 Cylinder – 180HP
7 Cylinder – 210HP
8 Cylinder – 240HP
31A8 ½“: 8 ½” bore, 11 ½” stroke
Marine Engines – 540RPM
5 Cylinder – 312HP
6 Cylinder – 375HP
7 Cylinder – 437HP
8 Cylinder – 500HP
Stationary Engines – 514RPM
5 Cylinder – 325HP
6 Cylinder – 390HP
7 Cylinder – 455HP
8 Cylinder – 520HP

The cool part about the 31A engine line – it was a fully enclosed engine.   Removable covers covered the entirety of the engine, front to back, with a very 1930’s Art Deco type look to it.   It also looks like a toaster, and this will be the first model we cover in a series of “Engines that look like toasters”.

A 7 cylinder 31A6 ¼” setup for stationary service, driving a small generator. FM Photo – Click for larger.
A 5 Cylinder 31A8 ½“ setup for marine propulsion, with the Airflex clutch and a reduction gear. FM Photo – Click for larger.

While the engine is offered in two sizes, they are virtually identical engines, much like how the F-M 38 series (5 ¼” and 8 1/8” bore) were designed – parts were just “scaled down”.  The notable difference being that the smaller 31A6 ¼” used a timing chain for the camshaft drive, while the 31A8 ½“used a gear drive.  It seems to be that the larger 31A8 ½“ was much more common then the smaller bore, which seemed to be popular in smaller work boats.

The one piece cast crankcase and cam pocket. FM Photo – Click for larger.

Let’s do a quick walk through of some of the features of the 31A.

Up on top, the 31A used a very basic lump of a cylinder head, like most of the previous F-M engines.   A central fuel injection nozzle, along with a start air check valve, and a space for either a test cock or a start cartridge adaptor.   The cylinder heads bolt down onto the liners, with a simple copper gasket between the firing surfaces, and rubber rings on the water passages. 

31A Cylinder Head. FM Photo – Click for larger.

Unlike most previous large F-M engines which the cylinder liner sits on top of the main crankcase, the 31A uses a cylinder liner that inserts into the block.   The air inlet ports, and the exhaust ports are surrounded by a water jacket supplied through an unorthodox method.   Cooling water enters the engine into the (water jacketed) exhaust manifold.  A threaded fitting allows water to exit from the exhaust jacket, into the lower portion of the liner, flowing up through the head into a water header.   On the bottom of the liner was a simple O ring to seal the scavenging air from the crankcase. 

Note that there is no actual seal between the air and exhaust side of the liner. FM Photo – Click for larger.

The 31A series engines use only a conventional style full pressure oil system (unlike other models which used a combination of force feed Madison-Kipp lubricators as well as a pressure system), which force feed all of the bearing surfaces, as well as drilled crankshaft which feeds oil to the connecting rods and pistons.  The bearing shells for both the upper and lower main bearings, as well as the crankpin bearing shells were all interchangeable. 

The 31A piston used a set of bolts to hold the carrier to the piston. On the lower end, like all of the previous large bore FM engines, the crank pin bearings were in their own separate holder, thus when you had to pull a piston, you did not have to detach it from the crankshaft. FM Photo – Click for larger.

Scavenging air for the 31A series is provided by an attached vane style, oscillating blower.   In layman’s terms, it’s a big moving flap.  Incoming air comes in through a set of intake valves, gets compressed (1.5-3psi), and exits into the airbox through a set of discharge valves.   The moving vane is run off its own connecting rod on the forward end of the engine.  Intake air could be routed through the top, or front of the engine.  Engines so equipped with a compressor; this was driven off the lever that runs the blower vane. 

Oscillating vane style blower, and attached compressor. FM Photo – Click for larger.

Under the hood on the control end, things are a little more complicated.   To maintain the streamlined appearance, all the control rods are inside.   Follow the diagram – Incoming fuel comes into the fuel header on top of the injection pumps. Each injection pump is driven off the camshaft.  The fuel rack on the pumps is controlled by the governor – in this case, a direct reversing marine engine, using a Woodward SG8 governor.  Governor speed is controlled by a speed lever.   The governor is driven off the camshaft, which also drives the fuel pump, as well as a very basic, mechanical overspeed governor trip system.   Engine direction is controlled by a separate lever, which controls an interlock on the air side (to prevent the engine from starting if it is still moving in the opposite direction).

The fuel/control side. FM Photo – Click for Larger.

Moving on to the air system: The shift lever controls a rather complex pilot air system.  Driven off the camshaft gear drive train, is an air distributor.   Think of this like a distributer in a car.  Instead of controlling the firing order of spark plugs, it controls the air start sequence timing.  Putting the lever to start, air from the pilot valve, opens the air start relay valve, thus filling air header with start air.   At the same time, air from the distributor. opens a check valve on the appropriate cylinder, thus letting the start air in.    The same lever also has a cam that is tied into the fuel rack and governor, to set the fuel load when either in the start or run position.   In order to switch from ahead to astern, the shifter lever also controls a shifter cam, which in turn runs down to a shift fork inside the air start distributor.   This shifter moves a small camshaft to choose the appropriate timing for ahead or astern starting. 

Control air side of things. FM Photo – Click for Larger.
The rotary distributor valve that controls pilot air for starting in a specific direction. Much simpler then the large sliding camshafts a number of big bore engines used. FM Photo – Click for larger.

Stationary engines still use the same system; however, it is slightly simpler without having the additional moving shifter and gear for the reversable timing.  Stationary engines used a Woodward UG8 governor, with a faceplate and knobs for the extra controls. 

Unlike the larger 31A18 engine, these smaller engines have more provisions for attached pumps.   All the pumps (oil, raw water, soft water) are driven off the crankshaft through a flexible drive gear (a spring pack drives the gear to absorb any shocks) located under the blower.  In the case of the direct reversing engines, all the pumps are reversable (except the fuel pump, which has a directional switching valve).   One of the options for marine engines was a small reciprocating bilge pump that was driven off an eccentric on the cam idler gear.  Behind the flexible drive gear was the thrust bearing.   Often in cases of stationary engines, water pumps were typically electric driven pumps.

Pump drive system, as well as the thrust bearing. This is on the front end of the engine, under the blower. FM Photo – Click for larger.

Both models of the 31A included an unusual option – either an Airflex style clutch and a reduction gear, or a Twin Disk clutch.  This clutch was simply an “on – off” per say.  The reduction gear would be built to match a vessel’s specific.  The Airflex clutch was also available for stationary applications and could be offered on either end of the engine. 

The reverse gear (made by FM) and Airflex clutch (likely a Fawick). FM photo – Click for larger.

In the case of the 31A8 ½“ engine, an optional dual fuel version was offered, the 31AD8 ½“.   While the specifications are the same, the AD engine included a few additional parts in order to run on both Diesel and Natural Gas – however, Diesel was still used as a pilot fuel.  On the control side of the AD engine, tied into the control lever is a pilot valve, which controls an oil pressure activated gas shut off valve – which is also tied into the governor overspeed – thus, if the engine overspeed’s, or shuts down for any reason, the natural gas is shut off.  On top of the engine, a gas manifold runs alongside the cylinder heads.  On each of the cylinder heads is a valve, which is operated by a set of push rods and rockers off the main cam shaft.   The fuel injection pumps are a duplex style, that when the engine is run in Diesel mode, the normal amount of fuel is injected, however when operating in dual fuel mode, a smaller metered amount of Diesel is injected as a pilot fuel for the Natural Gas.   When running in Diesel mode, the gas injection valves are still functioning, however nothing happens as they open when the exhaust stroke starts. 

Gas valve lever assembly. FM Photo – Click for larger.

Fairbanks-Morse 31A Gallery

Cutaway view of the 31A8 ½“ engine. FM Photo – Click for larger.
A trio of FM 6 cylinder 31AD8 ½“ engines at the Roodhouse, IL municipal power plant. The AD version of the engine can be spotted by having the extra set of duplex filters (the Diesel version only has one set). These engines each drive a 265kW alternator. Fairbanks -Morse News. Click for larger.
An FM 5 Cylinder 31A8 ½“ driving a 75,000gpm pump at the Corpus Christi flood control station “B”. Fairbanks-Morse News. Click for larger.
At the Corpus Christie pump station “A”, a trio of 5 cylinder 31A8 ½“ engines drive 54″ 75,000gpm pumps, for a combined capacity of 225,000gpm of flood control. The station also housed a 75hp FM electric motor driven, 36″ 27,000gpm pump. Fairbanks-Morse News. Click for larger.
A postcard of the FM Chicago showroom, including a full scale cutaway 31A engine. This is not just a drawing, it actually existed! I have seen a photo of Mr. Morse standing in front of it. FM Photo – Click for larger.
The City of Stockton, KS would replace a pair of FM Y engines with a single FM 8 cylinder 31AD8 ½“ in 1949. In the background are a pair of FM 32E14 engines. I would be curious as to what size generator this 31A drove. This plant would run these engines full load 96.7% of the year, a testament to the reliability of FM’s big bore engines. Fairbanks-Morse News. Click for larger.
The Glennallen Diesel Plant, in Glennallen, AK originally had a pair of FM 8 Cylinder 31A8 ½“ engines. These would be replaced in the 1970s by 38OP engines. Cooper Valley Electric Photo – Click for larger.

The F-M 31A series (with the exception being the 18” bore for stationary power generation) never really caught on.   By the 1950’s when F-M was really pushing the engines, there was already smaller and lighter engines making around the same power.   Not to mention, the plethora of cheap WWII surplus engines, including many F-M 38D OP’s which went on to do just about every job under the sun.   By 1958, F-M severely reduced engine production to just the 38D OP engines (in both bore sizes), the 31A18, and the small 45C and 49B engines.  All of the older models were now discontinued (such as the 31A, 32D, 37F, 33D: any of the older pump or crankcase scavenged engines).  One of (the?) last running example of a 31A8 ½” was the NOAA research vessel “John N. Cobb”, which was operational until 2008 when the crank snapped.   The vessel has recently been sold for use as a fishing boat, and I would imagine will be repowered.  The small, former Canadian buoy tender “Nokomis” has a 31A6 ¼” and has been up for grabs for some time now, if it has not been scrapped yet.   I imagine there may still be a handful of older stationary examples hiding around the country somewhere. W.W. Williams became the parts supply company for these engines when F-M gave up the rights, however nothing has been available for quite some time.   Interestingly enough, Williams listed a  4 3/8” as well as a 10 ½” bore 31Aengine, however I have seen nothing about this in any of my F-M company literature, production lists or any advertising of the period. 

Video from youtube user oldtacomamarine (which used to be a fantastic website for old engines, but it has gone dormant) of the John N. Cobb just before the crank broke. Here is the link to their page on her engine: John N. Cobb at Old Tacoma Marine
Cover of the FM brochure on the 31A engine.

As always, I welcome any questions, comments, corrections, etc.. I would love to hear if any more of these engines are out in hiding. I have manuals for all 3 sizes, as well as the parts book for the 18″ should anyone need a copy. Since I know I will likely never get to play with any of these big old engines, I started the CAD work to 3D print a scale model..the first of many engines I plan on building.

An unexpected find…

A few month back, I was exploring a new store by my house called Rescued Metals & Equipment. Essentially, this is the “dumpster diving” division of a local scrapyard. They pull out any worthwhile metal, cool stuff, new steel/aluminum stock and anything else they might be able to sell. The ultimate in surplus stores. Browsing the racks, I stumbled on something I immediately recognized, an intake/exhaust valve. Without blinking, I bought it of course!

Yeah, its a big ass valve. Lets try that with something for reference..

On the left is your typical 6V battery, and on the right is a Cleveland 248/278/278A exhaust valve.

After tracking the part number stamped on it, it turns out this is for an Enterprise DSRV-16 engine. These were introduced in the 1950’s, and made up until the early 1980’s (by then it was a DeLaval Enterprise). Its a 17″ x 21″ 4 stroke engine running at 405RPM making 9,000HP with quad turbos. These were pretty common as standby generators at Nuclear plants, as well as ship propulsion engines.

From the 1957 Diesel Engine Catalog

If your ever in Southwest Michigan, be sure to stop by Rescued Metals. Its different every week, and they come up some some really cool stuff! Be sure to check out their Facebook page below.


https://www.facebook.com/RescuedMetals/

Oh, and the valve makes a fantastic paper towel holder in my office!

Fairbanks Morse Engine List

Unfortunately due to travel, I have not had nearly the time I would like lately to sit down and type up another article. This week however, I will provide some interesting reading. This is a Fairbanks Morse bulletin from 1958, that details every diesel engine model they ever produced. The one downside, is that it only covers the model, and not the cylinder arrangements offered for each one.

F-M was another one of those companies that seemed to have a new “model of the week” engine. Its impressive that quite a number of these engines survived, both as museum pieces, as well as a fair bit still in service today, unlike Winton and many other early diesels.

Keep in mind, this is a 1958 list, and does not cover the later engines that popped up when Colt took over, such as the 38A20, or any of the Pielstick engines.

Click each photo for a larger version.

EMD 567 Spotters Guide

Something that I see quite often on various forums and the like, is misidentification of the early EMD 567 series engines.  Like all engine manufactures of the day, the EMD 567 line was under constant revision throughout the years.  This is not meant to be any sort of history of the engine,  just a simple way to differentiate the different types of 567 engines. 

The “Straight” 567

One of the first EMC 567’s built in July of 1938 for the “Thomas E. Moran”. While the base engine was built by EMC, it was then sent to Cleveland Diesel to be converted into a marine engine. Note that while the rectangular crankcase and airbox covers are the same, the crankcase ones are horizontal, while the airbox ones are vertical. These engines would be removed and replaced with a single 12-278A in 1944.

The first production model of the 567 was just that, the 567. Often people dont associate this engine, thinking the 567A was the original, but it was not. The first 567 engines used an interesting top deck design, with extended crab studs to hold down the covers, with a simple rectangular hatch over each injector. The first pair of production 567’s according to the EMD book “Diesel War Power”, were for the Moran Towing “Thomas E. Moran”, built by Defoe Shipbuilding in 1938. Ironically, an engine designed specifically for locomotives, would be first installed in a tug. The engines (one pictured above) were V8, 660HP/750 RPM engines that drove a 400kW generator, with a 24kW belt drive exciter above.

A spare 12-567 on a flat car at the Illinois Railway Museum

The first Railroad use of the 567 would follow in October of 1938, with a set of E4 Streamliners for the Seaboard Air Line railroad. Each E4 used a pair of 1000HP 12-567’s. The first and most obvious way to spot the straight 567, is the very wide housing for the blower drive gears, making the rear end of the engine rather wide. EMC/Cleveland would supply special versions of this engine to the USCG for use in a fleet of Icebreaking Tugs, with a narrowed version of this case, however all of the standard production engines used this wide case. By now, the engine also featured matching doors on both the crankcase and airbox, as well as a larger, removable cover that spanned the entire top deck.

Click for a larger version

Note the upper deck of the engine in the “U” (cast) or “V” (fabricated) upper portion where the exhaust coming out of the heads would mate up with the upper manifolds. The original EMC 567 design is well outlined in Eugene Kettering’s paper on the History and Development of the 567, which will be linked to at the end of this article.

The production EMC 567 would be offered in 6, 8, 12 and 16 cylinder models

567A

With the onset of WWII, the 567 by now was being refined into the 567A starting around 1942. What would put the 567 line on the map, would be the advent of the Navy LST program. The majority of the LST program would in turn use a pair of 12-567A engines (dubbed ATLP/ATLS for Aux. Tank Landing Port or Starboard), driving a 2.48:1 reduction gear through an air clutch. On land the 567A was being used in all of EMD’s line of locomotives from switchers to road power.

Click for a larger version

The 567A would take the idea of the narrowed blower drive on the USCG 8-567’s, and make it even narrower, thus saving crucial space in the engine room. Midway through the LST program in 1943, the two piece floating piston and carrier design was adopted. Also to note, is the entire upper deck was modified, and now the exhaust from the heads ran inside of a water deck. Note the smooth cast ducts for the scavenging air from the blowers into the airbox.

An early Cleveland 12-567A with a Falk clutch/gear drive. J. Boggess Collection.

The 567A package used in the LST would go on to be one of the most common repower package for tugboats in the 1950’s and 60’s, something we will get into more in the future.

567B

The 567B was introduced after the end of WWII. The 567B was very similar to the 567A, with one main spotting difference on the outside. The 567B now used a ribbed air duct casting from the blowers into the airbox.

Mechanically the 567B was essentially the same as the 567B, with the difference being the attached oil strainer housing on the front end of the engine.

567C

In 1953, EMD introduced the 567C. The C block engine was essentially an all new engine. The C blocks major change involved the elimination of the water deck liners, and the use of O rings to seal them. These O rings were prone to fail, and would thus cause water contamination of the lube oil system. The C liners used a bolted on water inlet type, completely eliminating the water deck.

A Cleveland 16-567C with a Falk 16MB reverse reduction gear. This was one of the more popular marine uses of the engine through the 1960’s. J. Boggess Collection.

The easiest way to spot a 567C – is that the block introduced a few new changes. First is the round inspection covers on both the airbox and crankcase. The fuel rails were moved to the inside of the upper deck, as well as an all new style of hinged upper deck cover, with snap latches. The thing about the 567C is that it is also identical to its replacement, the 645 series.

Click for a larger version

567CR

A short one here – the 567CR was only an 8 cylinder engine, that used a revised firing order, hence the “R”, to help with vibration issues. Externally it is exactly the same.

567D

The final installment in the 567 lifespan development is the 567D of 1959. The D line of engines introduced the turbocharger. EMD, unlike Detroit and Cleveland would develop their own turbo, that was driven off of the gear train through a clutch at low speeds, and would freewheel when the exhaust pressure built up. The 567D was only offered as a 16 cylinder engine, and topped out at 2500HP. Later on they would take the turbo off for a few select applications, and squeezed 1800HP out of it.

The turbo versions of the 567D while overall successful engines and were a major stepping stone to the 645 development, they were plagued with turbo issues. Several railroads choose to pull the turbos off and replace them with the traditional roots blowers.

567AC and 567BC

The AC and BC engines, from the outside are identical to their original counterpart. Internally, the engines were upgraded to use “C” power liners. The only way to spot one of these, would be to remove an airbox cover and see if the water manifold is present.

567CA

Not to be confused with the above conversions, the 567CA engine is its own beast. While it was not any sort of a new development, the CA engine was an EMD designed direct replacement for the 567ATL LST engines that by now were in hundreds of commercial boats.

12-567CA in the tugboat “Jupiter”

The CA engine used a new crankcase with “C” specs, however there were several recycled parts off of the original ATL engines. The smooth blower ducts, as well as the entire top deck assembly, complete with the external fuel lines and removable covers were recycled off the original engines.

The 12-567CA engines were developed in the early 1960’s as drop in replacements.

645C

Yes – the 645C is actually a 567. The 645C is a 567C that uses 645 power assembly’s. Again, like the AC and BC conversions, the 645C is not distinguishable from the outside.

Wrap up…

Please note, I wrote this simple as a way to try and help to visually distinguish each model of 567. One thing to keep in mind, is the 567 was a very modular engine at the end of the day, and quite a few components are interchangeable throughout the entire production line, some easier then others.

As mentioned previously, the 567 was an EMC/EMD design, and was built in the LaGrange shop. Between 1938 and 1961, both marine and stationary versions of of the 567’s were marketed and sold under the Cleveland Diesel banner, having been converted for such uses in their Cleveland shops. These engines carry Cleveland Diesel builders plates, and numbers.

Preston Cook, one of the leading authority on EMD, has a fantastic write up at the following link which gets a bit more into the technical sides of the model development over the production spans.

Preston Cook – EMD 567 in the 21st Century

Eugene Kettering’s paper “History and Development of the 567 Series General Motors Locomotive Engine” hosted over at Utah Rails.

Old Advertising III

This week, we have a 1941 classic, featuring the Carl Hussman Company, and a trio of Cleveland 16-567’s.

Click for a larger version

Unfortunately, I can not really say much about Carl Hussman outside of what is in the ad – I cant find anything! Other then they obviously made some spring isolation assembly’s.

What I can add though – is about those engines. The main trio featured, are Cleveland 16-567’s. Yes – They are Electro-Motive Corporation (at the time) designed, and even built in LaGrange – however these engines carried Cleveland Diesel plates. EMC (EMD), Cleveland Diesel and Detroit Diesel all fell under one banner after 1937 – the General Motors Diesel Power line. Locomotives fell under EMC/EMD, Marine and Stationary engines fell under Cleveland Diesel, and small engines up to 250HP under the Detroit line.

These 3 16-567’s were some of the earliest applications of these engines. These engines were shipped 11/1938, as 1000HP/600RPM gen-sets for the Alfred I. duPont building in Miami, Florida. Interestingly enough, 2 of the 3 were listed as being in emergency generator railcars, however as we can see – all 3 are inside the building. It is unknown if the order was changed in the process, of if the plant was reconfigured between 1938 and 1941 when this ad was made.

The 4th engine in the ad, the “225HP 8 Cylinder” is a Cleveland 8-233A engine. This was a small, 200HP/1200RPM engine. As with the early Winton designed engines, this was a 4 stroke, and one of the engines that ultimately would lead to the development of the Detroit 71 series. The 233A line was one of the engines used by Electro-Motive in the early railcars, as well as a yacht propulsion engine, and standby generator used in some early Aircraft Carriers.

The better question is – Are these engines still there?

Fairbanks-Morse 31A18

Naturally, as things progress – engines got bigger.  For Fairbanks-Morse, the 31A18/31AD18 was the largest production engine they made…at least until the 1960’s…but we will get to that later.    Fairbanks-Morse introduced their line of 31A engines around 1945 or so, calling them the new “En-bloc” engines, meaning “as a whole” in the dictionary.   While previous FM engines were made of various castings, bases, liners, air box, exhaust belt, etc., the new 31A line used a one-piece cast block, in which the cylinder liners went into (not on top of like earlier models). The cam and main bearing pockets were cast right into the block, ensuring perfect alignment every time (or so they touted), as well as featuring an integral oscillating scavenging blower.   The 31A series was offered in a 6 ¼” and an 8 ½” bore for marine and stationary service, as well as a giant 18” bore engine for stationary power generating service, and thus the 31A18 was born.

Fairbanks Morse 10 Cylinder 31A18

The 31A18 used an 18” bore, with a 27” stroke, rated at 277 RPM.   FM also offered the 31A18 in a dual fuel model, the 31AD18 – which used diesel as a pilot fuel for natural gas operation.   The engines were offered in the following configurations:

– 6 Cylinder, 2100HP, 140,000lb/143,000lb (31AD18)
– 8 Cylinder, 2800HP, 193,000lb/197,000lb (31AD18)
– 10 Cylinder, 3500HP, 247,000lb/251,000lb (31AD18)

End cutaway view of the 31AD18

One of the few options offered was in way of the scavenging blower – The engine could be equipped with an oscillating vane blower, or none at all, with the scavenging air being supplied by a separate motor driven blower in the plant.   It appears most applications went with the separate motor driven unit.     Lubricating oil was supplied by a duplex system with an engine driven gear pump handling piston cooling, main bearings, crankpins, camshaft, injection pumps and blower (if equipped).  A separate pair of Madison-Kipp lubricators driven off the main camshaft supplied oil to each cylinder liner wall by means of 6 lines going to each. The camshaft also chain drives the fuel oil service pump.  Jacket water cooling is handled off a main header (remember, there is no internal water passages in the cast block) on the lower potion of the block, up through the liners and heads, and out through an upper header.   The engine has no water pumps of its own (common in large stationary engines), with separate motor driven pumps for the closed loop soft water in the engine, and a raw water system for the heat exchangers.  

Main casting of the 10 Cylinder model. Note the casting line between the first 4 Cylinders and the last 6. The blocks were cast as 4 Cylinder blower/non blower sections and 6 Cylinder sections.
The 31A18 used a rather unique piston. While it was not a floating piston, it did in essence use a carrier, however it was bolted in place through the skirt. The crown was a separate piece with studs, which held it all together.

The 31A/31AD18 were essentially the same engine except for the dual fuel equipment.   In addition to the standard equipment, the 31AD18 used an additional chain driven upper camshaft to control the gas admission valves, supplied by a separate header on the top end of the engine. 

The rather unorthodox method of driving the upper camshaft and fuel pump.

Around 1955, Fairbanks Morse added to the 31A18 line, by introducing a 12-cylinder option, putting out 4200HP.   Production of the 31A18 lasted until the late 1960’s – well past the production of all of the other FM engines that were not model opposed Piston models.  While FM does not support the 31A18 line anymore, there are still numerous examples of these engines still in service in various municipal power plants.   While the 31A18 family was the largest production Fairbanks Morse engine, it was not the largest. That honor would go to the 38A20 Opposed Piston engine.

A pair of 38AD18 engines in an unknown power plant. For the life of me I can not find the source of this photo. If anyone recognizes it please let me know so I can properly credit it.

Midway Island, part of the Midway Atoll in the Pacific is home to a small power plant with a single FM 38AD18. Check out this link for photos of the Midway power plant. Note that this engine has the attached engine driven blower.

Midway Island Power Plant Photos

FM 31AD18 running at the Rochelle Illinois power plant. Note the large grey pipe coming up from the floor in the front of the engine, this is the air intake, as this engine does not have the attached blower. This plant is home to many old engines including FM’s, Worthingtons and Nordbergs. Video from youtube user dzlrod

As always, I welcome and and all comments, additions, corrections and anything else.