By Staff
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Bessemer (Carruthers and Fithian).
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Figure 1.
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Figure 3. Convertible class with a photo of the Palm
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Figure 2. Photo of a Boardman half breed, representing the 4-cycle half breed class.
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Bashline Design, Inc., 2379 Lake Avenue, Allison Park,
Pennsylvania 15101

The Coolspring Power museum is unique in its intense interest in
internal combustion engine history. The following article was
researched and written several years ago by the Museum staff. It
briefly discusses the development and unique history of the oil
field half breed engine.

The Half Breed Engine, or ‘Breed’ as it is
affectionately called in the oil patch, is a steam engine converted
into a gas engine. To our knowledge, this topic has not been
addressed in any of the recent gas engine literature. Considering
the proximity of Coolspring Power Museum to the old eastern oil
field and its desire to represent locally built equipment of
historical importance, the half breed engine represents a
significant subject.

The half breed begins life as a steam engine, usually an oil
field drilling engine, which is then converted to an internal
combustion engine by either replacing the steam cylinder with a gas
cylinder or converting the existing steam cylinder to gas
operation. Several methods of the latter were employed, but all to
the same end. The exceptions are the ‘convertibles’ that
were designed to be easily switched to either gas or steam
operation or in one case, for both simultaneously.

In the early decades of oil production, starting around the turn
of the century when well productivity was decreasing, aging steam
boilers were becoming unsafe and troublesome to maintain. It was no
longer economical to fire a boiler for only a few hours of pumping
each day. It would have been much easier to install a new gas
engine that could be easily (hopefully) started whenever desired
and run for short periods, without wasting the fuel to heat a great
quantity of water in the boiler. However, at the time, the cost of
a new gas engine presented a considerable expense. Therefore, it
was much more economical to convert the old steam engine into a gas
engine, which could be done at a fraction of the cost of a new
engine. Soon literally scores of manufacturers of half breeds
sprang up in towns associated with oil production.

The deviation in this trend was the convertible engine. This
type of conversion gave the oil producer the flexibility of having
a gas engine for intermittent pumping use while still retaining the
smooth, dependable and reversible power of steam for servicing the
well. For those unfamiliar, servicing included pulling the rods and
tubing to clean and maintain the pump parts at the bottom of the
well. Convertible technology was used primarily in the southwestern
Pennsylvania fields.

The types of half breeds can literally number into the hundreds.
Coolspring Power Museum research has identified at least 20 makes
of steam engines still existing in the field, with many more
existing only in old records or probably having passed entirely
into oblivion. Approximately the same number of makes of gas
cylinders and conversions have been identified. The total number of
engine types would be the product of both! This, plus the
interchanging of parts such as flywheels, certainly accounts for
why no two half breeds ever look exactly alike.

Historically, the invention of the half breed seems to belong to
Bessemer. Although several patents appeared about the same time,
credit must go to Dr. Edwin J. Fithian of Portersville,
Pennsylvania, who was described as a physician with a
‘mechanical term of mind’. Practicing in an oil field area,
Fithian recognized the need for a cheap internal combustion pumping
engine that could utilize existing steam engine components. The
idea of the half breed was thus born! In 1897 he completed and
tested a 10 HP model but was turned down on a proposed sale to the
Oil Well Supply Company. Needing a partner and a source of
manufacture, Fithian turned to John Carruthers, a successful local
machine operator. They also recognized the need for a friction
clutch to transmit the power from their gas cylinder, and in 1898
the Carruthers-Fithian Clutch Company was organized. They moved to
Grove City, Pennsylvania to start production and their successor,
Cooper-Bessemer, continues at that location today.

The idea was an instant success. In 1898, an oil producer could
convert his steam engine with a 10 HP gas cylinder and clutch
combination for $120.00. A 15 HP unit could be bought for $175.00
and with practice, two men could easily complete the conversion in
one day. Bessemer’s chief customer, the South Penn Oil Company,
wanted so many that they paid royalties to manufacture additional
half breeds in their own shop at Allegheny, Pennsylvania. During
the first three years of manufacture, 10,000 pumping units were
converted in Pennsylvania and West Virginia.

During this time, of course, other companies were capitalizing
on the idea and obtaining patents for minor design changes. These
included Braden of Parkersburg, West Virginia, Gardner of
Washington, Pennsylvania, and Palm of Butler, Pennsylvania. Many
more were simply producing plain two-cycle gas cylinders that could
easily be attached to any steam frame and doing so without patent
protection or worry about infringement upon others.

It is interesting to note that some companies offered a half
breed using all their own new parts. The 1914 Bovaird-Seyfang
catalog offers a ‘B&S Converted Gas Engine’ new and
complete using their two-cycle gas cylinder and their steam engine
frame. These engines were offered in 12 HP, 15 HP, and 20 HP models
and were advertised to meet the demand of a moderately priced gas
engine. If desired, one could purchase the gas cylinder and convert
his own steam engine.

Half breed engines can be divided into three main types, each of
which are discussed below. These are the 2-cycle, 4-cycle, and the
convertible which, although limited in production, includes both 2
and 4-cycle models.

Two-Cycle Half Breeds

By far, the most common type of half breed was the 2-cycle. This
is due to their utter simplicity; all that was needed was to attach
a 2-cycle gas cylinder to a steam frame and one could start
pumping. There were no extra moving parts required except replacing
the plain steam engine pulley with a clutch pulley. A steam engine
could be started and stopped easily with full load simply by
turning on the steam where a gas engine cannot, hence the need for
the clutch. Otherwise the steam engine remained intact, using the
original bed, crank, crosshead and flywheel.

Flywheels varied greatly, due to availability and desired
inertia. Since most steam engines used in the oil field had a
31/4 inch crank shaft diameter (some used a 3
inch and some used a 31/2 inch), flywheel
interchanging was usually no problem. By adding a second flywheel
on the off side, a smoother running and nicer appearing engine was
obtained. All the oil field type steam engines originally used only
one flywheel to which ‘balance rings’ or extra weights
could be attached for drilling or pumping deeper wells.

Ignition for early half breed engines was almost always the
dependable hot tube. However, high tension ignition became
available in later years with the advent of the Wico R1 and OC
magnetos. But magnetos always presented a problem with worn parts
and shorting due to moisture, where the hot tube was easily
maintained and understood. Remember that at the turn of the century
gas engines represented high technology to many, and the simpler
the engine, the more oil that would be pumped.

Half breed fuel was usually natural gas, which was readily
obtained from the well itself. It could power the engine and heat
the hot tube and still be used in much smaller quantities than to
fire a huge boiler.

Governing was sometimes by a simple flyball governor, usually a
Pickering, or was more likely done manually. It was practical and
more convenient to run the engine ‘on the cock’, which is
to open the quarter-turn gas control cock to admit only enough fuel
to maintain the desired pumping speed. Hence the reason for finding
so many governors lying on the engine house floor. When the
governor was used, it usually merely served as an overspeed device
to control the engine whenever the well pumped off. Notable
exceptions to this were the Bessemer and the White-Thomas, which
both used pendulum-type hit and miss governors. Only one example of
a White-Thomas has been discovered, but for the many Bessemers
known, it is usually found that their governors have been
disconnected and they are run ‘on the cock’.

Some of the many types of 2-cycle cylinders are listed at the
end of this article. It seems that every small oil patch foundry
made its own version of the 2-cycle half breed. Figure 1, a
photograph of an Oil Well Supply Cylinder on a Gibbs and Sterret
frame on display at Coolspring Power Museum, is typical of the
early 2-cycle half breed.

Four Cycle Half Breeds

The 4-cycle half breed, although similar in overall purpose,
posed a more complex problem in conversion due to the addition of
more moving parts required to operate the exhaust valve mechanism.
Usually they retained the steam cylinder, converting it to gas
usage. Advantages of the 4-cycle design include easier starting and
more reliable running. The Coolspring Power Museum continues to
research the topic of 4-cycle half breeds. There are five types
known, each of which is explored below.

The Boardman (manufactured by Robert Boardman Company, Oil City,
Pennsylvania)-This relatively rare engine retained the steam
cylinder which was sleeved to close the steam ports. A new cylinder
head was produced which carried the intake and exhaust valves. The
original steam passages were then used as a cooling water jacket.
Governing was either flyball or fixed length intake pipe. A timing
gear was attached to the frame which meshed with a gear on the
crankshaft, and a push rod operated the exhaust valve. The intake
valve was automatic. These engines ran very smoothly and presented
a pleasing appearance. The Coolspring Power Museum has on display a
very unusual Boardman equipped with a gasoline-fired hot tube and a
liquid gasoline pressurized fuel injection system, the only known
example of this technology.

The Pugh and Tinsman, Bruin, Pennsylvania-This very rare engine
again retained the steam cylinder and was converted in a manner
similar to the Boardman. Pugh and Tinsman used hit and miss
governing with either a vertical flyball or a pendulum. The valves
are positioned vertically under the head with only the exhaust
valve being power operated. Again, a timing gear and cam mechanism
had to be attached to the frame. Examples of this engine represent
local ingenuity and much crude blacksmith work.

The Evans, Butler, Pennsylvania- This engine represents a usual
type Evans overhead valve cylinder attached to a steam frame.
Although it appears well done and practical, only two examples are
known to exist.

The Sheffer, Emlenton, Pennsylvania-This engine used a
valve-in-head, ported, 4-cycle cylinder attached to a steam frame
plus the further addition of a timing gear, pushrod and rocker arm
mechanism. With a huge port and uncooled valve chests, it must not
have been very successful. Two examples have been identified and
governing is not apparent on either. Ignition was by hot tube. This
is another example of local design to produce yet another half

The Acme-Abel, Titusville Iron Works, Titusville,
Pennsylvania-This engine is not a true half breed, being built from
the ground up as a gas engine. However, it does use
Titusville’s heavy Acme steam engine frame, crank and
cross-head assembly, factory modified to include the integral
bosses and lugs needed for gas engine use. It uses their typical 20
HP Abel gas cylinder and a single Olin gas engine type flywheel.
The governor is the hit and miss type in the timing gear as would
be used on an Olin or an Abel. Since both Olin and Abel gas engines
were being manufactured concurrently, the Acme-Abel’s purpose
is not clearly understood.

Convertible Half Breeds

This is a unique class of half breeds designed to operate on
either gas or steam. Their purpose is discussed earlier in this
article. There are four types known to exist, with a fifth shown
only on patent drawings. This subject will be studied in more depth
by the Coolspring Power Museum at a later date, but for this
article each type is briefly mentioned below.

The Braden, Parkersburg, West Virginia-This design exists only
as a patent drawing, but is significant in being the oldest
convertible design, dating to 1898. It is simply a 2-cycle gas
cylinder and a double acting D-valve steam cylinder mounted in
tandem on a common frame. The patent implies that the gas cylinder
is mounted ahead of a steam engine with the steam engine being
modified by a stuffing box head. However the drawing implies an
engine with a common frame under both cylinders. With no existing
examples, this question appears lost to history, if indeed an
engine was ever built. One does wonder if this is the same Braden
that appears in Butler several years later building regular 2-cycle
half breeds and clutches.

The Gardner, W. D. Gardner Convertible Gas & Steam Engine
Company, Washington, Pennsylvania- This appears to be the first
practical 2 cycle convertible half breed and has a 1904 patent. The
Gardner design replaces the entire cylinder and uses a gridiron
valve to isolate the steam chest for gas use. Hence, it can
function as a regular 2-cycle gas engine or a regular D-valve steam
engine. Although the company went into receivership about 1920,
judging by the number of Gardners in use into the 1970’s, it
must have been a successful design. The next two designs mentioned
appear to be copies of this machine.

The Either, B. D. Northrup Company, Washington, Pennsylvania-
The Either, appropriately named, appears to be a close copy of the
Gardner, the only difference being three in-cylinder mounted globe
valves to isolate the steam chest and the intake chest. Local
research implies that Mr. Northrup was initially a Gardner employee
who saw the opportunity to start his own business. Apparently
during the oil boom, demand was great enough to support both
concerns. Although sometimes nicknamed ‘Neithers’, the
Eithers appear to have been as successful as the Gardners. The fate
of the Northrup Company included successful patent infringement
lawsuit by Gardner. Later Eithers bore the Gardner name as the

The DC&U, B. D. Tillinghast Company, McDonald,
Pennsylvania-Located in the oil field that boasted the largest
gusher in Pennsylvania, flowing at 25,000 barrels per day, the
DC&U represents the third 2-cycle convertible built in
Washington County. This southwestern corner of Pennsylvania is the
only area where the convertibles flourished and probably represents
most of their production. It should be noted that these three firms
also built plain 2-cycle half breeds as well. This engine
represents the patent of Dahlberg, Clicquenoi, and Uhlin, and again
is similar to the Gardner being either a 2-cycle gas engine or a
D-valve steam engine.

The Palm, Butler, Pennsylvania- This is the only known 4-cycle
convertible and represents the 1899 patent of George Palm. The
cylinder is completely his product and on the near side carries a
regular D-valve steam chest. A Stephenson link completes the
reversing mechanism. The off side of the engine carries the intake
and exhaust valve cages, with the latter being operated by push-rod
from a gearless ‘wig-wag’ cross-over cam arrangement.
Crossed helical gears operate a vertical governor behind the
crankshaft which throttles the air and gas mixture. Ignition is by
hot tube. By removing the push rod and turning a built-in
quarter-turn cock, either gas or steam operation is obtained. The
unique feature, and it is advertised as such, is that it can run on
gas and steam simultaneously; a single acting steam engine behind
the piston and a 4 cycle gas engine in front. But why?


This brief article introduces the reader to the interesting
technology of the half breed oil field engine. This type of engine,
produced mainly in western Pennsylvania, played a significant role
in the oil field and yet is neglected by most collectors,
historians, and the literature. It is hoped that this will
contribute to the recorded history of the internal combustion
engine and will increase the enjoyment of all those interested.


1. Keller, David N., Cooper Industries, 1833 – 1983. Ohio
University Press, Athens, p. 33

2. Ibid, p. 34

3. Bovaird and Seyfang Manufacturing Company 1914 Catalog,
Bradford, Pennsylvania, p. 52.

A Complete Outfit

A Bessemer Design Gas Cylinder Outfit consists of: One Cylinder
with cylinder head and piston head, rod and rings complete; One
Short Shaft Automatic Friction Clutch, 14 or 16 inches diameter;
One Cast Brass Polished Cylinder Lubricator; Two Cast Brass
Polished Grease Cups for crank and crosshead pin; One Hit-or-Miss
Governor, with eccentric and eccentric rod complete; One Air and
Gas Valve complete; One Bunsen Burner; One Dial Stop Cock; One Cast
Iron, Gasometer-Acting, Dry Gas Regulator.

Gas Engine Magazine
Gas Engine Magazine
Preserving the History of Internal Combustion Engines