34 SURFACE MACHINERY AND METHODS FOR OIL-WELL PUMPING.
Oil engines are used widely in fields whose gas supply has failed
and where cheap electric power is not available. -As prime movers
for pumping they are generally of the horizontal one-cylinder, two-
cycle explosive type, 10 to 60 horsepower, and use crude oil. Sand
and water in suspension in the oil are removed as completely as pos-
sible by heating and filtering before the oil enters the engine. Even
after treatment, some crude oil contains enough sand to cut out the
cylinder. One company in southern Illinois rebores the cylinders
of oil engines about every six months. This same difficulty from sand
in the crude oil has been encountered in some of the Kansas oil fields.
However, at other places the crude oil used seems to give no trouble
in oil engines, as in some of the Texas and Oklahoma oil fields.
The oil engine is fully described in a Bureau of Mines bulletin.9
An abstract of that part of the first 18 pages, with particular refer-
ence to the explosive two-stroke cycle type, which is most commonly
seen in use in the oil fields, is quoted herewith:
GENERAL CHARACTERISTICS AND TYPES OF OIL ENGINES.
The term oil engine, as generally used at the present time, is applied to
internal-combustion engines that burn directly in the cylinder heavy liquid
fuels of high boiling points, the fuel being injected into the compressed air
shortly before or at the completion of the compression stroke. The distinguish-
ing features of oil engines are that the fuel vapor is not absorbed by air before
it is admitted to the cylinder, and that no inflammable mixture of vapor and
air is compressed preceding its ignition. Oil engines compress air alone, and
the heat of compression is used to ignite the fuel, which burns by consuming
the oxygen of the air in the cylinder, the engine transforming the heat energy
To facilitate and accelerate the burning of a liquid fuel it must either be
vaporized, atomized, or intimately mixed with air immediately preceding its
Light, highly volatile liquid fuels, such as benzols, gasolines, alcohol, and
distillates, offer no particular difficulties to vaporization; the air in its passage
to the engine cylinder readily absorbs the fuel vapors and forms a combustible
mixture, which is ignited electrically in the cylinder.
The process of charging the air with fuel vapors is called carburetion.. The
more volatile fuels, like gasoline, can be carbureted at ordinary atmospheric
temperatures--that is, without previous heating of the air or the fuel. Liquid
fuels with higher boiling points may require heating of the air or the fuel, or
both, to bring about their evaporation and absorption by the air preceding
combustion. In the heavy-oil engine the vaporizing of the fuel takes place
inside of the engine. As a fuel with a high boiling point can not be evaporated
at moderate temperatures, thorough mechanical division preceding ignition and
combustion is necessary.
* Haas, Herbert, The Diesel engine; its fuels and its uses: Bull. 156, Bureau of Mines,
1918, 133 pp.
George, H. C. Surface Machinery and Methods for Oil-Well Pumping. Washington D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc12407/. Accessed February 1, 2015.