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then runs across an old, poorly designed, or worn-out engine that will run badly and cannot be depended upon, but in most cases a little adjustment here and there, a little lubrication, or some other small matter is all that is required. During a number of years' experience in handling and repairing gasolene engines, the author has yet to find a motor which could not be made to runsave in one or two cases where the engine was completely worn out and fit only for the junk heap.

Many books have been written on gas engines and their care and operation, but in the majority of cases these works are either too technical or are confined to one particular class of engines. Others describe and discuss oil, kerosene, and producer-gas engines, as well as those designed to operate on gasolene, and this is apt to be very confusing to the inexperienced, for while, strictly speaking, all these are gas engines, yet the individual peculiarities of different fuels require certain variations in design and operation in the motors and each should be made a separate study in itself. The purpose of the present work is to furnish all the necessary information regarding gasolene engines in simple language free from technical terms and as far as possible cover all variations, types, and classes of these motors and their various parts, accessories, and appliances. In order to illustrate the various types of engines and devices certain makes with distinctive characters have been used as examples, but the author wishes it clearly understood that such mention of a certain make of engine or accessory does not imply that it is the best or that it is recommended or endorsed by this work. Such mention merely

indicates that the motor or appliance is typical of its class and is a well known ană standard make.

As the number of gasolene motors on the market is steadily increasing and there are over ten thousand manufacturers of explosive engines in the United States to-day, it is practically impossible to mention more than a very limited portion of the various designs, innovations and improvements constantly being made in this industry. In all gasolene engines the principle is the same, and the care and operation identical, and the man who becomes thoroughly familiar with one engine will have no trouble in mastering any other.

As technical terms cannot be avoided under certain conditions, such as ordering new parts, making repairs, machine-shop work, etc., a glossary of such terms with an explanation of the meaning of each has been added to the work as well as an alphabetically arranged table of common troubles and their symptoms and remedies, features which the author believes will prove of great value to all owners, users, or operators of gasolene motors.

GASOLENE ENGINES

CHAPTER I

TYPES OF MOTORS. OPERATION AND EXPLANATION OF TWO-CYCLE

AND FOUR-CYCLE MOTORS

ALL gas, gasolene, or oil motors, known collectively as Explosive Engines, may be roughly divided into two classes or types: the Two-cycle or Two-stroke engines and the Four-cycle or Four-stroke engines.

While these two types are quite distinct in their construction and operation, yet the principle in each is the same. A charge of gas, gasolene, or oil vapor is drawn into the cylinder, is compressed therein by a piston, and while under compression is ignited by an electric spark or similar device. The force of the exploding gas drives down the piston which, acting upon a crank, transmits the power of the explosion to a revolving shaft and thence to the boat, vehicle, or machine requiring the power.

It will thus be seen that a gas of the highest explosive

* The author is well aware that certain six-cycle motors have been built and used to some extent. In these engines the additional idle stroke is utilized to draw a charge of clean air into the cylinder in order to more perfectly scavenge the burnt gases. Such motors have not come into general use, however, and the ordinary operator is not likely to encounter an engine of this type. They are not considered of sufficient importance to be worthy of consideration in the present work.

power, an ignition device that can be depended upon, and a cylinder that will not leak and lose compression are the most necessary essentials for the proper operation of a gas motor.

The simplest form of gasolene engine is the Two-cycle in which the parts may be reduced to a minimum, only three moving parts being absolutely essential (Fig. 1).

In this figure the piston A is represented as being at the upward limit of its stroke with the space between the top of piston and top of cylinder B filled with a charge of compressed gas. At this position, or "Firing Stroke," an electric spark takes place at C and ignites the gas which, exploding, drives the piston A downward. At the point illustrated in Fig. 2 the opening D in the cylinder wall is uncovered by the piston, and the burning and practically exhausted gas rushes out through this opening and escapes. Almost at the same instant the opening E is uncovered and a fresh charge of gas-which has been contained in the base F-is forced up through the opening G to take the place of the exhausted charge (Fig. 3). The momentum of the moving fly-wheel and shaft now carries the piston on its upward course, closing the openings or “portsD and E and at the same time drawing by suction a fresh charge of gas or gasolene vapor into the base through the opening H (Fig. 4). As the piston reaches the top of its stroke a spark again ignites the compressed charge, the piston is again forced down, and the operation repeated over and over again. In this motor it will readily be seen that an explosion or impulse takes place at every complete revolution of the shaft or, in other words, at every two strokes of the

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