THE ABC OF THE DIESEL ENGINE

e [Music] w internal combustion is the great source of power which has made possible the transportation system we have today and here are the boys who provide the power that drives your car our old friends air fuel and hey Sparky come come on out ignition [Music] hey fellas look here what kind of an engine is that I don't know you got me that's a big diesel engine boys a what a diesel engine it's an internal combustion engine but it works differently than a gasoline engine can we make it go of course you can make it go in fact it won't go without you why don't you look it over [Music] what are we waiting for come on fellas let's go yes air fuel and ignition cooperate to give the diesel its power but they get together in somewhat different ways than in an automobile engine no carburetor yeah no carburetor no battery no coil no spark plugs what an engine yes that's right boys no carburetor no coil or wiring no spark plugs but in a diesel engine you get along without them and we're going to find out why and how remember in the gasoline engine air and fuel are combined in the carburetor to form an explosive mixture fuel enters the carburetor at the float chamber air is sucked in through an air cleaner then pulled past a tiny opening called the fuel F jet which mixes fuel in the proper proportion to air this explosive mist is fed into the cylinder on the intake stroke of the Piston then compressed on the compression [Music] stroke meanwhile a third member of the internal combustion Trio is waiting in the ignition system in the form of electrical energy [Applause] at the proper time the distributor sends him on his way to the cylinder where the explosive mixture has been compressed and Bam the explosion that provides the power stroke then the Piston comes up on the exhaust stroke to push the burned gases out of the cylinder and so we have the fourstroke power cycle of the gasoline engine which drives your car intake compression power exhaust the basic parts of a diesel engine are the same as those of a gasoline engine there are cylinders Pistons connecting rods and a crankshaft the valve mechanism is essentially the same as in a gasoline engine there is also a cooling system to get rid of the heat caused by combustion this is a three-cylinder inline engine but various Arrangements of the cylinders are practical D type pancake and so on in a diesel engine there is no carburetor to mix air and fuel outside the cylinder and no electrical system to provide ignition in the form of high voltage electricity but ignition doesn't have to be electrical ignition is simply heat heat enough to set fire to [Music] something if you squeeze any substance hard enough compress it it gets hot even our friend air can be compressed to a very high temperature high enough to ignite fuel if if it is present lucky thing fuel wasn't along or there would have been an explosion in this principle of compression ignition lies the major difference between gasoline and diesel engines a compression ratio of about 8 to1 is common in automobile engines today on the compression stroke the Piston squeezes the air fuel mixture in the chamber to 1/8 of its form of volume the diesel is a higher compression engine at the top of a diesel compression stroke the air in the cylinder may be squeezed to as little as 12th of the former volume and when you squeeze air that hard it gets hot 1,000° F or higher because of higher compression and therefore higher temperatures in the cylinders diesel engines can use fuels which are less volatile than gasoline higher compression and the resulting higher pressures require a diesel engine to be made stronger than a gasoline engine and because of the higher compression Fuel and air cannot be mixed outside the cylinder in a carburetor the mix you would start burning too soon the air has to be compressed alone and the fuel put into the cylinder just when we want it to start burning in place of the carburetor we have a fuel injection system to get the fuel into the combustion chamber because we don't need a spark plug we can put the fuel nozzle in its place at the top of the cylinder connected to a high pressure pump to force in the fuel now we have all the basic parts necessary for a diesel engine to make it go we need only air fuel and ignition and here comes the first one air whoops the valve closes and there's no way out notice that at the end of Diesel's intake stroke the Cinder is filled with air all Air not an air fuel mixture what is this another Squeeze Play exactly my friend you're going to work in a diesel engine then the compression stroke and his temperature rises steadily until it's hot enough to start fuel burning now if fuel were only here hey what's up your pals are waiting for you this will do it fuel is pumped to the nozzle and sprayed into the chamber through tiny holes where the heated air ignites it immediately the power stroke is completed and the exhaust valve opens as the Piston Returns on the exhaust stroke driving the burned gases out of the cylinder that completes the Diesel's fourstroke cycle intake compression power exhaust the power comes from the expansion of the burning gases just as in a gasoline engine but in a diesel they expand more because of the higher compression and greater heat that's one reason for the Diesel's high efficiency from the very beginning of the diesel just before 1900 size and weight were a great disadvantage because diesels were so efficient and economical Engineers have constantly worked to cut down the ratio of weight to horsepower and make them more useful and versatile engines this work has eventually resulted in making the diesel engine light enough to use in heavyduty vehicles the adoption of the automotive type electric selfstarter also contributed to its wider usefulness while research men were improving and refining basic diesel engine designs they also developed a two cycle diesel engine instead of having the engine itself draw in fresh air and expel the burned gases two cycle diesel engines have a special fan or air pump to do the job [Music] in many two cycle engines the intake valve is eliminated and replaced with a row of holes or intake ports in the cylinder wall then to force large quantities of air into the cylinder quickly a blower is added on the outside this is sort of a fan or air pump the blower most commonly used today is the roots type blower [Music] it works somewhat like a pair of revolving doors of course with the ordinary revolving doors anyone can come in and just as easily get out but if we move the two doors together so they interlock then drive one clockwise the other counterclockwise we have the principle of the roots type blower this unit provides a continuous supply of fresh air for combustion and a means of blowing exhaust gases out whenever the valve is open the blower itself is a casing with two rotors each having lobes which fit together somewhat like gear teeth they give a constant flow of fresh air this supply of air makes possible the two-stroke cycle commonly called the two cycle diesel [Music] engine as the Piston starts up it seals off the ports and goes on to compress and heat the air to a high temperature at the top of the stroke fuel is injected and the expansion of burning gases drives the Piston down on the power stroke as the Piston is driven down the exhaust valve opens the ports are uncovered and the blower forces air in driving out the burned gases and filling the cylinder with fresh air two or even four exhaust valves may be used in removing gases and that's the complete cycle compression power compression power in a two cycle diesel every downstroke is a power stroke the heart of every diesel is the fuel injection system all diesels have a nozzle in each cylinder through which fuel is sprayed into the hot compressed air in some engines the high pressure pump and nozzle are combined into individual units one for each cylinder other engines have a central pressure pump that supplies fuel to all cylinders in principle the in cus spray nozzle is like a squirt gun but how does it work fill it up little fellow and we'll find out when we apply pressure fuel squirts out the holes in the bottom simple isn't it yes it's simple enough in principle but these fuel injectors are precise mechanisms that accurately measure the fuel and force it into the cylinder at exactly the right time the Jets through which the fuel must be forced have a diameter as small as 5 1,000 of an inch less than the size of a human hair a control changes the amount of fuel injected into the cylinder as the throt bottle is opened or [Music] closed as the Piston approaches the top of the compression stroke a tiny drop of oil is injected into the combustion chamber under pressures as high as 20,000 lb per square in since the beginning of the diesel engine changes in design plus improvements in materials have brought the weight of the modern diesel down to as low as 6 lb per [Music] horsepower we sure made those diesel engines go hey fellas we're the power Trio that's us why in one of those engines we could drive we could drive a say mister what do we drive with diesel engines a great many things boys the productivity economy and reliability of the modern diesel engine make it particularly useful wherever there is tough work to be done on any job big or small you'll find Dependable efficient Diesel power for instance Diesel power builds and maintains our modern highways and Powers the trucks and buses that use them Diesel power builds dams and irrigation canals operates oil fields and mines raw materials Diesel power propels tugboats and towboats fishing and pleasurecraft and all sizes of military vehicles and Craft This Modern reliable power plant becomes more versatile every day driving farm tractors and machinery pulling the fast Freight and streamlined passenger trains diesel power is also used to safeguard our hospitals communication centers and factories during [Music] emergencies and to provide precise electric power for missile guidance and outer defense lines yes even the carnival carries its own diesel power units [Music] [Music] oh [Music]