WHERE MILEAGE BEGINS

e [Music] [Applause] [Music] [Applause] [Music] today's automobile engine is taken very much for granted we know it converts gasoline into power and power takes us where we want to go what more could you ask and yet an engine such as this once was a dream a dream going back nearly 300 years the dream was practical but the fuels were not it was only when gasoline came along that a practical internal combustion engine could be built this gleaming piece of Machinery looks and is complex yet in reality it works on simple principles the basic basic one being the fourstroke cycle the principle may be compared to the Loading and firing of an old-fashioned muzzle loading Cannon loading the cannon for example was a slow motion counterpart of the engine cylinder's intake stroke ramming or packing the powder charge served the same purpose as the cylinder's compression stroke when the cannon was fired the expanding gases Force the shot out of the barrel just as the Piston is forced to move on the engine's power stroke and then cleaning the barrel of burned gases was like the exhaust stroke in the engine the analogy can be carried further by changing the cannon Barrel into an accurately machined cylinder the ram rod becomes a piston that slides up and down in the cylinder to make the Piston fit the cylinder accurately enough to form a seal rings are set in grooves around the Piston then to convert the up and down motion of the Piston into rotary motion the ram rod handle becomes a connecting rod that is joined to a crankshaft the heavy weight of a flywheel keeps the engine running smoothly between power strokes the fuel that powers the engine is a mixture of gasoline and air fed to the cylinder by a carburetor the carburetor Works something like a lady's atomizer in an atomizer the air pushed through the tube by squeezing the bulb forces a mixture of air and perfume from the nozzle in a fine spray in the carburetor suction caused by the moving Pistons of the engine pulls air past an open tube this causes liquid fuel to be drawn into the Airstream in the form of a fine spray it is this combustible mixture that powers the internal combustion engine more than 10,000 gallons of air are needed to burn each single gallon of gasoline the pipe that carries this mixture from the carburetor to the cylinder is the intake manifold an intake valve admits the combustible mixture into the cylinder a spark plug produces the spark that ignites the mixture and an exhaust valve lets out the burnt gases which are carried away through the exhaust manifold to make the valves open and close at the proper time requires an assembly of Parts actuated by the crankshaft each valve should open once for every two revolutions of the engine so the two cam shafts are geared to turn at half the speed of the crankshaft the cams are really knobs that in turning push up on the valve lifter and push rod and then let them down again the top of the push rod lifts one end of the rocker arm the other end goes down and pushes the intake valve open against the pressure of the coil spring this admits the fuel air mixture into the cylinder as the intake valve closes the Piston moves up on its compression stroke the spark plug should now fire the mixture let's see where we get the electricity to create the spark the six or 12vt battery current is adequate for the starter lights and other accessories but it's not strong enough to fire the spark plug so the battery current is passed through an ignition coil here's how the coil Works surrounding an iron core is a primary winding and a secondary winding when current flows in the primary winding a magnetic field builds up when the current flow is broken the magnetic field collapses and produces a momentary surge of voltage as high as 20,000 volts in the secondary winding to get this effect a pair of contacts called breaker points continually break and reconnect the primary circuit at the spark plug the high voltage current arrives at just the right moment to create a clean hot spark that ignites the air gasoline mixture in the cylinder with these basic parts the engine operates in a cycle of four strokes of the Piston the first stroke pulls the gasoline air mixture from the carburetor in through the open intake valve to fill the chamber in the cylinder the second stroke compresses the mixture to about 2 tons of force on a 4-in piston the third or power stroke actually begins after the spark plug ignites the mixture the intense Heat of the fuel combustion expands the gases against the Piston with a force of nearly 5 1/2 tons the fourth stroke of the cycle forces the burnt gases out through the exhaust valve and manifold the four strokes come in Rapid succession intake compression power exhaust intake compression power exhaust at Highway cruising speed there may be over 4,000 Strokes per minute in each cylinder of the engine as the number of cylinders is increased the flow of power becomes smoother as the power stroke occurs in one cylinder compression is going on in the second intake in another and exhaust in still another cylinder thus one piston is always Furnishing power to the crankshaft with more than four cylinders there is actually overlapping of power strokes when the cylinders are in line like this each Piston's connecting rod is attached to a different crank of the crankshaft in a modern V8 engine two rows of four cylinders each are set at an angle using a common crankshaft the fourstroke cycle is of course the same Automotive Engineers use terms such as bore stroke displacement to describe the capacity or size of an engine let's see what these terms mean bore is the measurement of the inside diameter of a cylinder stroke is the distance the Piston travels displacement is the volume swept by the Piston the engine's displacement is the total for all cylinders now let's see what is meant by compression ratio if the air gasoline mixture is squeezed by the Piston to 1/8 its volume before firing the compression ratio is 8 to1 the higher the compression ratio that is the more the mixture is squeezed the more efficient and Powerful the engine becomes here's the reason at a low compression ratio say 4:1 the mixture's pressure at the top of the stroke may be 100 lb per square in combustion raises this 3 to four times resulting in 300 to 400 lb per square in push on the piston at the higher ratio 8:1 the mixture's pressure at the top of the stroke is 200 lb per square in again combustion multiplies it by 3 to 4 resulting in 600 to 800 lb per square in push on the Piston which means more power but there's one drawback at a low compression ratio when the spark ignites the fuel mixture the flame spreads evenly across the chamber giving a smooth power impulse but at a high compression ratio as the flame spreads the unburned mixture sometimes gets so hot it ignites itself causing a loud knock one solution to Knocking which causes loss of power and can damage the engine lies in the gasoline specialized refining or the addition of tetraethyl lead gives gasoline its antiock property and so it is high octane gasoline and improved engine design that makes possible today's higher compression ratios the internal combustion engine is basically a heat engine it is heat produced by the combustion that expands the gases that drive the piston for 4000° F each time an explosion occurs in the cylinder the temperature momentarily Rises to its much as this figure nearly a third of this heat is transformed into useful power another third is dissipated with the exhaust gases the remaining heat goes into the engine parts most of this heat must be removed by the cooling system to avoid damage to the engine a water jacket surrounding parts of the cylinders the valves and the spark plugs contains circulating water that carries off most of the Heat this side view of the engine shows the cooling system in diagram a pump forces water from the bottom of the radiator through the water jacket where it absorbs heat from the engine parts and then back to the radiator for cooling the fan pulls air through the radiator to carry heat away from the hot water a thermostat in the system regulates the cooling when the engine is cold the thermostat controls the flow of water to the radiator so that the engine will warm up quickly when the water gets hot between 160 to 180° the thermostat opens and lets the water flow to the radiator for cooling today's engine in theory is not too far removed from the visions of yesterday's dreamers but in design and manufacturer ah there the true genius of our centuries Engineers is evident for each part made Remember by The Identical thousands is a Precision piece each part fits with other Precision pieces and miraculously the whole comes together as a smoothly working power [Music] plant the crankshaft is the first item it goes under the engine block and so we'll have to turn the block bottom [Music] [Applause] [Music] up these are the main bearing inserts [Music] now we're ready for the [Music] crankshaft bearing caps for the crankshaft [Music] [Music] now the [Music] Pistons every connecting rod gets its bearing insert [Music] la [Applause] [Music] this is the cam shaft it will be tied in with the crankshaft by a chain drive and harmonic [Music] balancer the oil pump is put together [Music] next the oil pan the oil filter assembly now the [Music] flywheel the two cylinder heads and the intake and exhaust valves get together then the 16 valve springs [Music] [Music] now the valve lifters and push rods 16 of each [Music] kind then the rocker arms [Applause] [Music] [Music] the Breather fixture and the intake manifold go on [Music] next then the two exhaust manifolds [Music] this is the fuel pump and here comes the carburetor [Music] [Applause] [Music] these are the fuel lines which connect fuel pump and carburetor next the ignition coil the distributor Drive [Music] mechanism and the ignition harness these are Shields to protect the spark plug [Music] leads now the valve covers go [Music] on and the air cleaner [Applause] time now for the starter to go in [Music] place this is the water [Music] pump the generator [Music] the fan the fan [Music] [Applause] belt this then is the power plant that runs our cars it may develop 200 or 300 or more horsepower but all that power is useless unless it is transmitted to the wheels a train of devices does this first in the train is the clutch with its diaphragm spring and its friction disc which connects and disconnects the engine and the transmission without stopping the car or the engine the transmission is mechanism of Gears that makes it possible to vary the speed of the engine and the wheels to take care of differences in load and speed of the car large and small gears join in various combinations to give us the well-known low second and high how the transmission Works can be shown with this diagram to start the car moving a shift into low gear gives High turning effort and low speed at the rear wheels once the car is in motion such great turning effort is no longer needed and a shift to Second gives a somewhat higher speed at the rear wheels next a shift into high connects the engine and the wheels directly now the engine power is used most effectively for normal driving in Reverse as in low gear great turning effort at low speed is needed now of course the drive shaft turns in the opposite direction a large proportion of modern cars are built with an automatic transmission the clutch pedal and the gearshift lever are eliminated and the transmission automatically adjusts the relationship between engine speed and car speed for the best performance a universal joint between the transmission and the drive shaft allows the rear axle to move up and down the rear axle is made up of two sets of Gears the drive gears transmit power from the drive shaft to the rear axle the differential gears allow independent rotation of each wheel which is necessary in going around corners the ch is now fitted with the entire power producing mechanism and the means of transmitting that power to the rear wheels the car will run but it also has to stop the brake is composed of shoes faced with friction material and a drum of hard metal when the brake pedal is pushed the brake shoe pushes against the rotating drum and stops the Turning wheel smooth equalized braking is gained through the hydraulic braking system and in many modern cars power brakes can stop the car with only the slightest pressure on the pedal the steering mechanism is strong dependable and easy to operate when the steering wheel is turned the steering gear here causes an arm to move and change the direction of the front wheels power steering in many cars makes the effort needed at the steering wheel almost negligible thus we have the modern automobile that is the Envy of the world in it are built performance efficiency economy and safety any one of many body styles will give it comfort and smart appearance the modern car has everything in fact except the skill of the driver and in this electronic age the Restless minds of the automotive Engineers May someday build even that into this marvelous machine a