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GAS AND OIL ENGINES
SIMPLY EXPLAINED
_An Elementary Instruction Book for Amateurs
and Engine Attendants_
BY
WALTER C. RUNCIMAN
_FULLY ILLUSTRATED_
LONDON
Model Engineer Series. The "Model Engineer"
Series, no. 26.
1905
CONTENTS
CHAP. PAGE
PREFACE 5
I. INTRODUCTORY 7
II. THE COMPONENT PARTS OF AN ENGINE 13
III. HOW A GAS ENGINE WORKS 22
IV. IGNITION DEVICES 33
V. MAGNETO IGNITION 47
VI. GOVERNING 51
VII. CAMS AND VALVE SETTINGS 63
VIII. OIL ENGINES 81
PREFACE
My object in placing this handbook before the reader is to provide him
with a simple and straightforward explanation of how and why a gas
engine, or an oil engine, works. The main features and peculiarities in
the construction of these engines are described, while the methods and
precautions necessary to arrive at desirable results are detailed as
fully as the limited space permits. I have aimed at supplying just that
information which my experience shows is most needed by the user and by
the amateur builder of small power engines. In place of giving a mere
list of common engine troubles and their remedies, I have thought it
better to endeavour to explain thoroughly the fundamental principles and
essentials of good running, so that should any difficulty arise, the
engine attendant will be able to reason out for himself the cause of the
trouble, and will thus know the proper remedy to apply. This will give
him a command over his engine which should render him equal to any
emergency.
WALTER C. RUNCIMAN.
LONDON, E.C.
GAS AND OIL ENGINES
SIMPLY EXPLAINED
CHAPTER I
INTRODUCTORY
The history of the gas engine goes back a long way, and the history of
the internal combustion engine proper further still. It will be
interesting to recount the main points in the history of the development
of the class of engine we shall deal with in the following pages, in
order to show what huge strides were made soon after the correct and
most workable theory had been formulated.
In 1678 Abbe Hautefeuille explained how a machine could be constructed
to work with gunpowder as fuel. His arrangement was to explode the
gunpowder in a closed vessel provided with valves, and cool the products
of combustion, and so cause a partial vacuum to be formed. By the aid of
such a machine, water could be raised. This inventor, however, does not
seem to have carried out any experiments.
In 1685 Huyghens designed another powder machine; and Papin, in 1688,
described a similar machine, which was provided with regular valves, as
devised by himself, in the _Proceedings of the Leipsic Academy_, 1688.
From this time until 1791, when John Barber took out a patent for the
production of force by the combustion of hydrocarbon in air, practically
no advancement was made. The latter patent, curiously enough, comprised
a very primitive form of rotary engine. Barber proposed to turn coal,
oil, or other combustible stuff into gas by means of external firing,
and then to mix the gases so produced with air in a vessel called the
exploder. This mixture was then ignited as it issued from the vessel,
and the ensuing flash caused a paddle-wheel to rotate. Mention is also
made that it was an object to inject a little water into the exploder,
in order to strengthen the force of the flash.
Robert Street's patent of 1794 mentions a piston engine, in the cylinder
of which, coal tar, spirit, or turpentine was vaporised, the gases being
ignited by a light burning outside the cylinder. The piston in this
engine was thrown upwards, this in turn forcing a pump piston down which
did work in raising water. This was the first real gas engine, though it
was crude and very imperfectly arranged.
In 1801 Franzose Lebon described a machine to be driven by means of
coal-gas. Two pumps were used to compress air and gas, and the mixture
was fired, as recommended by the inventor, by an electric spark, and
drove a piston in a double-working cylinder.
The atmospheric engine of Samuel Brown, 1823, had a piston working in a
cylinder into which gas was introduced, and the latter, being ignited,
expanded the air in cylinder whilst burning like a flame. The fly-wheel
carried the piston up to the top of its stroke, then water was used to
cool the burnt gases, which also escaped through valves, the latter
closing when the piston had reached the top of its stroke. A partial
vacuum was formed, and the atmospheric pressure did work on the piston
on its down stroke. A number of cylinders were required in this engine,
three being shown in the specification all connected to the same
crank-shaft. According to the _Mechanic's Magazine_, such an engine with
a complete gas generating plant was fitted to a boat which ran as an
experiment upon the Thames.
A two-cylinder engine working on to a beam was built in Paris, but no
useful results were obtained.
Wright's engine of 1833 used a mixture of combustible gas and air, which
operated like steam in a steam engine. This engine had a water-jacket,
centrifugal governor, and flame ignition. In 1838 Barnett applied the
principle of compression to a single-acting engine. He also employed a
gas and air pump, which were placed respectively on either side of the
engine cylinder, communication being established between the receiver
into which the pumps delivered and the working cylinder as the charge
was fired. The double-acting engines which Barnett devised later were
not so successful.
From this time to about 1860 very few practical developments are
recorded. A number of French and English patents were taken out,
referring to hydrogen motors, but are not of much practical value.
Lenoir's patent, dating from 24th January 1860, refers to a form of
engine which received considerable commercial support, and consequently
became very popular. A manufacturer, named Marinoni, built several of
these engines, which were set to work in Paris in a short time. Then,
due to sudden demand, the Lenoir Company was formed to undertake the
manufacture of these engines. It was claimed that a 4-horse-power engine
could be run at a cost of 3.4 shillings per day, or just one half the
cost of a steam engine using 9.9 pounds of coal per horse-power per
hour. Many similar exaggerated accounts of their economy in consumption
were circulated, and the public, on the strength of these figures,
bought.
It was understood that 17.6 cubic ft. of gas were required per
horse-power per hour, but it was found that as much as 105 cubic ft.
were often consumed. The discrepancy between the stated figures and the
actual performance of the engine was a disappointment to the using
public, and, as a result, the Lenoir engine got a bad name.
Hugon, director of the Parisian gas-works, who, together with Reithmann,
a watchmaker of Muenich, hotly contested Lenoir's priority to this
invention, brought out a modification of this engine. He cooled the
cylinder by injecting water as well as using a water-jacket, and used
flame instead of electric ignition. The consumption was now brought down
to 87.5 cubic ft.
At the second Parisian International Exhibition, 1867, an atmospheric
engine, invented by Otto & Langen about this time, was shown. In this
engine a free piston was used in a vertical cylinder, the former being
thrown up by the force of the explosion. The only work done on the
up-stroke was that to overcome the weight of the piston and piston rod,
and the latter being made in the form of a rack, engaged with a toothed
wheel on the axle as the piston descended, causing the fly-wheel and
pulley to rotate.
Barsanti and Matteucci were engaged in devising and experimenting with
an engine very similar to this some years before, but Otto & Langen, no
doubt, worked quite independently. Barsanti's engine never became a
commercial article; while Otto & Langen's firm, it is said, held their
own for ten years, and turned out about 4000 engines. In 1862 the French
engineer, Beau de Rochas, laid down the necessary conditions which must
prevail in order to obtain maximum efficiency. His patent says there are
four conditions for perfectly utilising the force of expansion of gas in
an engine.
(1) Largest possible cylinder volume contained by a minimum of surface.
(2) The highest possible speed of working.
(3) Maximum expansion.
(4) Maximum pressure at beginning of expansion.
These are the conditions and principles, briefly stated, that combine to
form the now well-known cycle upon which most gas engines work at the
present time.
It was not until 1876, fifteen years after these principles had been
enumerated, that Otto carried them into practical effect when he brought
out a new type of engine, with compression before ignition, higher
piston speed, more rapid expansion, and a general reduction of
dimensions for a given power. Due to this achievement, the cycle above
referred to has always been termed the "Otto" cycle.