PRIME MOVERS AND POWER PLANT MACHINERY.
speed engines. The piston valve and the poppet, or drop, valve are
suitable for engines with high pressure and superheated steam. How-
ever, the piston valve is not so economical of steam as is the Corliss
The slide-valve engine is now made only for drilling. It is used
for pumping only in emergencies.
Although the electric motor has replaced the steam engine in
some oil fields for drilling, steam is generally more common, because
of flexibility of speed and efficiency under overloads.
For pumping, however, and for general power service, the gas
engine, the oil engine, or the electric motor have largely replaced the
Plate V shows a typical slide-valve steam engine, as used in the
oil fields for drilling and pumping: a, Steam cylinder; b, throttle
valve operated by wire cord, c, from derrick, when drilling or pulling
rods or tubing; d, engine bed; e, split-hub flywheel; f, pulley; g,
water pump for supplying water to boilers; h, boiler-water heater; j,
engine link; k, reverse lever; 1, valve rod and slide; and m, steam
About 25 years ago, the gas supply became so depleted in the
eastern United States that a gas engine cylinder was made to re-
place the steam cylinder on the oil-field drilling and pumping en-
gine. One manufacturer, B. D. Tillinghast, of McDonald, Pa.,
developed a convertible gas and steam cylinder. An engine equipped
with this cylinder is used as a gas engine for pumping oil wells, and
as a steam engine for pulling rods and tubing and cleaning out
Manufacturers used oil-field steam engine dimensions in designing
these gas engine and convertible gas and steam cylinders, so they
can supply a gas cylinder or convertible steam and gas cylinder with
the necessary instructions for installation on the steam engine bed
for any size and make of steam engine. Many of these old steam
engines, converted to gas engines or engines which can use either gas
or steam, have been in use for years in the older oil fields of the
eastern United States.
From this beginning the single-cylinder, horizontal gas engine, in
sizes from 10 to 60 horsepower, has become the universal prime mover
for pumping oil wells. The 20-horsepower to 35-horsepower sizes
are the most common.
Most of the gas engines of more than 60 to 75 horsepower are mul-
tiple cylinder and many are vertical; they are used at central power
stations and at casing-head gasoline plants.
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 November 28, 2015.