Picture from Bowfin SS287 Web Page
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The Engine Room
Stories and Pictures of the Heart 
of Diesel Electric Boats
USS Charr powered by:
4  16-278A Diesel Engines, manufactured by General Motors.
Picture to Left .. Inboard Side
Picture to Right .. Outboard Side

Picture from Bowfin SS287 Web Page
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Reprinted from NAVPERS 16160-B 1961
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Manuals of Fleet & Guppy Boats.


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THE ENGINEERING PLANT

A.   The Type of Drive

6A1.  INTRODUCTION

   The successful use of the submarine has, to a great extent, been directly connected with the capabilities of the propulsion plant. Until the internal combustion engine was developed in the late 19th century, submarine designers depended on sail, manpower, or steam to propel their boats. Quite naturally, the effective range of the submarine was extremely short and application as a weapon of war extremely limited. With the development of the internal combustion engine and the use of electric storage batteries, the submarine designer had a propulsion plant of much greater reliability, and the submarine began to take on added prominence in navies of the world.
   Progress in the gasoline engine exceeded that of the diesel engine, and it was, therefore, used rather extensively in those boats built around the turn of the century. The inherent dangers of gasoline proved too dangerous to handle, so designers turned to the diesel engine, which under German development had made rapid strides. The diesel engine has been used as the normal power source in practically all submarines built since the beginning of World War I, until the present transition to Nuclear power.
6A2. GENERAL DESCRIPTION

   United States Navy submarines in service today use the diesel-electric drive for main propulsion; the primary source of power being 4 diesel engines of approximately 1,600 horsepower each. On certain classes of conversions, one or more main engines may have been removed to provide space for special equipment.
   Each main engine drives a main generator, which supplies electrical power for driving the main motors or charging the storage battery. The propellers are driven by double armature slow speed motors, which receive their power from either the generators or the storage battery.
   When running submerged, power for the main motors is supplied by the main storage battery or by the main generators on those submarines equipped with a snorkel.

B. The Diesel Installation

6B1.   GENERAL

   The Diesel plant consists of 4 2-cycle diesel engines, each directly connected to a main generator. Each of the 2 enginerooms contains 2 engines and their attached generators and the necessary associated auxiliary equipment.
   Engines used on our submarines today are made by either the general Motors Corp, or the Fairbanks-Morse & Co. Submarines built by Government owned yards use the Fairbanks-Morse engine, and submarines built by privately owned yards use the General Motore engine. There are a few exceptions to this general rule.

6B2.   THEORY OF OPERATION

   Diesel engines are internal combustion engines, which derive energy or work by burning fuel oil and air in the engine cylinders, thereby, producing high-pressure gases. These high-pressure gases force the pistons to move, causing the crankshaft to rotate.
as mentioned above, United States submarines use the two-stroke-cycle diesel engine. The sequence of events in this cycle is as follows:

            #1. When the piston is approximately at its maximum travel from the combustion chamber, a charge of air is admitted
                  to the cylinder.
            #2. The piston travels toward the combustion chamber, compressing the air in the cylinder. This is called the
                  compression stroke.
            #3. Near the end of the compression stroke, fuel is injected into the cylinder and immediately begins to burn. This
                  burning is progressive rather than instantaneous.
            #4. The gases of combustion, force the piston away from the combustion space. This is called the expansion or power
                  stroke.
            #5. Near the end of the power stroke, the exhaust gases are released from the cylinder, and a fresh charge of air is
                  again admitted, forcing out the remaining exhaust gases. The removal of the gases of combustion is usually called
                  scavenging.

6B3. CONSTRUCTION

   The General Motors engine is a V-type engine. The cylinders are arranged in 2 banks of 8 cylinders each, the 2 banks are at a 40° angle from each other. The combustion space is formed by the upper end, or crown, of the pistion and a cylinder head which contains the exhaust valves, fuel injector, and air start check valve.
   The Fairbanks-Morse engine is an opposed piston engine. The cylinders are arranged in-line, each having 10 cylinders containing 2 pistons. The combustion space is formed by the 2 pistions arriving near the center at the same time. The fule injector, air start check valve, and cylinder test cock and relief valve are inserted through the liner at the center. In place of exhaust valves, there are exhaust ports, which are uncovered by the lower piston.
   The frame or cylinder block of modern diesels, such as those used on United States submarines, is made of machined steel plates, which are welded together into a strong rigid unit. The build-up type of construction results in the best combination of strength and light weight.
   The frame is bored to receive the cylinder liners. The cylinder liners are made of alloy cast iron or mild steel, accurately bored and finished. Around the liner is fitted a mild steel water jacket. The liner and it's water jacket are called the liner assembly. This assembly is removable and can be replaced when worn.
   Pistons are made of cast iron and are fitted with cast iron piston rings. The connecting rods are forged steel and are attached to the piston by means of a casehardned, highly finished piece of steel called the piston pin, or wrist pin. A bronze bushing is inserted in the eye of the connecting rod to serve as a bearing surface for the piston pin.
   The crankshaft of the General Motors engine is made of heat treated alloy steel, with 8 cranks spaced 45° apart, and 9 main bearing surfaces or journals. The crankshaft of the Fairbanks Morse engine is made of fine grain, alloy cast iron, with 10 cranks spaced 36° apart, and it has 11 main bearing journals.
   Connecting rod bearings and main bearings are split shell, precious-type bearings, bronze backed and lined with a high grade, low friction bearing metal, known commercially as "Satco". The bearings are normally called Satco bearings.
   Camshafts are made of forged steel, and are used to control the action of various units of the engine. They are driven by gears or chain from the crankshaft and must be exactly timed to the rotation of the crankshaft.

6B4.   ENGINE SYSTEMS

   Fuel systems of engines used in United States submarines employ the solid, mechanical, injection principle. Fuel oil is drawn from the clean fule oil tank by a pump attached to and driven by the engine. This attached pump supplies the oil to injection pumps, which in turn, inject the fuel into the cylinder at the proper time, at the proper pressure, and in the required amount. The fuel injection mechanisims are actuated by the camshafts of the engine.