Part 2

Although many carburetors, in fact most of them, do not look like this drawing, yet their action is the same, and by careful study you will find that the same principles enter into their construction. Fig. 22 shows an actual sectional drawing of a carburetor used on a four-cylinder motor. In this particular carburetor, however, the float chamber and float surround the mixing chamber, and the float valve, instead of being directly under the float, is at the right hand side and is operated by means of a lever. The needle valve, which is the little round rod having a “T” handle, running up through the center of the mixing chamber, controls the amount of gasoline flowing from the gasoline chamber to the nozzle. The air comes up through the bottom and around the gasoline jet. At the left you will notice a small valve which opens downward, which you do not find on the other carburetor. It is known as an auxiliary air valve and allows a certain amount of air to be added to the mixture, a small quantity of which is sometimes needed to keep the mixture just right. The throttle valve, which looks like a damper in a stovepipe and which controls the amount of gasoline vapor going in to the engine, will be seen in the upper pipe.

THE IGNITION SYSTEM

The _ignition_ system is the name applied to the batteries, coils, commutator and spark plug which, acting as a whole, produce an _electric spark hot enough_ and at the _right time_ to _fire_ the charge in the cylinder. There are three ways in which an electric current may be obtained which have been found to be of practical use in automobile construction. First, by a dry battery; second, by a storage battery; and third, by magneto or dynamo. You can look up the construction of these things in any good book on electricity, so that I will not explain them further here. As the object of the whole system is to produce a sufficiently hot spark to fire the mixture at the right time, it is sometimes necessary to raise the pressure of the electric current. When either a dry battery or storage battery or a certain type of magneto is used, it is necessary to put it through what is known as an _induction coil_ in order to _raise_ the _pressure_ so it will be high enough to _jump across_ the two points in the cylinder.

An induction coil consists merely of a bundle of soft wires around which is wound two separate coils of wire. The first, known as the _primary_ winding, is of coarse wire, and the second, known as the _secondary_ winding, is of fine wire. When the current flowing through the primary coil is rapidly made and broken, another current of very high voltage is created in the secondary circuit.

When the current starts to flow through the primary winding, the bundle of wires immediately becomes a magnet and attracts the vibrator. As soon as this occurs, however, the flow of the current is interrupted and the vibrator resumes its former position and the action is repeated. Thus you can see that the coil automatically makes and breaks its own circuit. The rapidity with which this is done may be changed at will by adjusting the vibrator screw.

Having thus obtained an electric current of sufficient strength to fire the mixture it is necessary to supply a device which will _automatically_ open and close the electric circuit at the _proper_ time. Such a device is called a _commutator_ and consists of two parts; one a _rotating_ part, actuated by the engine, which makes a metallic contact with one or more points on a stationary part, the points being so located that contact occurs at the proper time for igniting the charge in any particular cylinder.

In the _four-cylinder_ wiring diagram (Fig. 25) various parts of an ignition system may be easily seen. The electric current is furnished either by a set of dry cells or by a storage battery. _Four_ individual coils and a _four point_ commutator are used. The commutator is driven by means of bevel gears from the engine itself. A single switch controls the whole circuit, it being provided with two points, making it possible for either battery to be used at will.

THE COOLING SYSTEM

In order to prevent the walls of the cylinder from becoming red hot, it is necessary to cool them by some means, and this is done by surrounding the cylinder with a _water jacket_ through which the cooling water is circulated.

In order to prevent the water from boiling and evaporating, thus making the constant addition of water necessary, a _radiator_ is introduced into the system. This radiator is made up of very thin tubes which give up their heat rapidly, thereby keeping the temperature of the water below the boiling point. A fan is also used sometimes to draw the air through between the tubes, thereby making the process of cooling take place more rapidly. The system is so arranged that the water is drawn from the lower part of the radiator where the water is coldest by means of a pump and forced up through the water jackets and back into the radiator again. Several different styles of pumps are used, but a very common one is the _gear pump_ shown in Fig. 32. As you will see by the drawing, it consists of two gears en mesh with each other which revolve in the direction indicated by the arrow. The water entering through the inlet pipe is drawn around the outside and forced out through the outlet at the top.

THE TWO-CYCLE MOTOR.

Although the four-stroke cycle type of motor is used by most of the automobile manufacturers, yet there is another type which has given such good results that it is destined to become one of the important forms to be used in gas engine vehicle manufacture.

It therefore merits a brief description. It has the advantage of being very simple in construction and operation, and for this reason it has become very popular among the marine engine builders, although with a few exceptions it has not as yet been accepted by motor car engineers. It is called a Two-stroke Cycle Motor, so named because it combines in _two strokes_ the series of changes ordinarily accomplished in _four_ in the four-stroke cycle type. Its operation may be seen by referring to the accompanying diagrams. It is first assumed that the engine is being turned over by hand in the direction indicated by the arrow. You will note that as the piston moves up it will uncover a port (H), allowing the gasoline vapor from the mixing chamber to enter the crank case. As soon as the piston moves down again, a port (J) will be opened, allowing the mixture which has just been compressed to rush through a “by-pass” (F), into the “combustion chamber,” or upper part of the cylinder. Now, as the piston moves up again on the next stroke, this charge is compressed still more, then as the piston reaches its uppermost position the charge is ignited and the engine begins to work under its own power. The gases continue to act on the piston until nearly the end of the stroke is reached, when you will notice, by referring to the drawing, the exhaust port (G) is passed. At this point the burned gases rush out into the air. You will also notice that in order to aid the discharge and fill the cylinder again, as the piston travels a little farther down, the inlet port will be again uncovered, and the next charge, which has meanwhile been taken into the crank case and compressed, will enter the cylinder, forcing the exhaust gases out.

In order to prevent the vapor which has just entered the cylinder from traveling straight across and out through the exhaust port, thus wasting a portion of the fuel, a “baffle plate” (K) is cast on top of the piston which deflects the gases toward the top of the combustion chamber, producing a sort of whirling action which tends to scavenge the cylinder most thoroughly. In order to prevent the burning gases from traveling back into the crank case and igniting the gas there, thus producing a “back explosion,” a wire gauze (S) is placed in the “_by-pass_.” You will note that this type of motor has no valves, no cams and no cam shaft, in fact, its simplicity is such that it practically cannot get out of adjustment. It therefore is a form of gas engine which as soon as engineers are able to educate the public to its peculiarities bids fair to become as popular and practical as the four-stroke cycle.

INDEX

Cam shaft 21 Cam 20 Carburetor 28 Commutator 33 Connecting rod 26 Connecting rod--lubrication of 26 Cooling system 37 Crank case 27 Crank shaft 25 Cycle--explanation of four-stroke type 9 Cycle--explanation of two-stroke type 42 Cylinder 16 Electrical ignition 31 Exhaust valve 21 Fan--radiator 39 Float chamber 28 Gasoline valve 30 Ignition 31 Induction coil 32 Inlet valve 21 Piston pin 24 Piston ring 24 Piston 23 Pump--water 38 Radiator 39 Spark plug 35 Switch--electric 36 Valve grinding 21 Valves 19 Valves--mechanism 21 Water cooling system 37 Water pump 38 Wiring diagram--four-cylinder 34 Wiring diagrams--single-cylinder 32

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A book of practical information for seekers after the fundamental facts regarding the gasoline engine and its application to the motor car.

Interesting and instructive to both the beginner and the expert--the former for information, the latter for reference.

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The book, which is handsomely bound in full cloth, printed on high-grade enameled paper, contains over 200 pages and 250 illustrations and covers the following subjects:

CONTENTS

=GENERAL THEORY OF GAS ENGINES=--Simple explanation of cycle--The four-stroke cycle--The two-stroke cycle--Advantages and disadvantages of each.

=MOTOR DESIGN=--CYLINDER, what it is and its use. VALVES, mechanical and automatic--Forms of valves--Valve timing and its influence on the motor--Valve grinding, how to do it--Valve nomenclature. CRANK CASE--The construction Bearings--Accessibility--Working parts--Uses. A crank case oiling system. CRANK SHAFTS--What they are--One, two, four and six-cylinder crank shafts--Crank case diagram, showing instantly conditions in all cylinders--Diagram showing firing points and sequence of same. CONNECTING RODS--Construction and material--Bearings and lubrication. PISTONS--Piston rings--Piston pins.

=THE CARBURETOR=--A very simple explanation of carburetion--The mixing valve--A few of the first types--Some of the modern carburetors--Foreign carburetors.

=IGNITION=--The make and break system--A simple explanation of the apparatus used. THE JUMP SPARK SYSTEM--Electrical units. SOURCES OF ELECTRICITY--The dry cell--The storage cell--Dynamos and magnetos--The spark coil--Commutators and timing devices--Spark plugs--Wiring diagrams.

=COOLING SYSTEM=--AIR COOLING. WATER COOLING--Direction of circulation--Radiators--Water pumps--Fans--Anti-freezing solutions.

=THE TRANSMISSION=--Reason for and use of transmission. SIMPLE EXPLANATION OF ACTION--Individual clutch type--The sliding gear--The three speed progressive--The three speed selective--The four speed selective--Planetary gear--Friction drive.

=METHODS OF DRIVING=--Single chain drive--Double chain drive--Bevel gear drive.

=RUNNING GEAR=--FRONT AXLE--Construction of--Steering Gear. REAR AXLE--Differential gear--The live axle--The dead axle--Wheel construction--Bearings.

=HORSE POWER DETERMINATIONS=--Engine testing--Indicated horse power--Brake horse power--Mechanical and heat efficiency--Road testing.

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Transcriber’s Notes

Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in the original book; otherwise they were not changed.

Simple typographical errors were corrected; unbalanced quotation marks were remedied when the change was obvious, and otherwise left unbalanced.

Illustrations in this eBook are shown as close as possible to their original positions in the printed book, so several of them actually are mid-paragraph. This was done because some of them are referenced only by their content, not by their names.

This book does not have a Table of Contents.

The index was not in good alphabetical order; Transcriber re-sorted it. It was not checked for correct page references.