Oil Field Engine News

By Staff
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The information in the table below comes from Bessemer-Duplicate
Parts. This undated manual lists specifications 1 thought would
interest readers, as it applies to all regular Bessemer engines.
Bessemer cylinder outfits (the kit to make what is commonly known
as a half-breed engine) were only built in 8, 12 and 15 HP models.
All measurements are in pounds and inches.

Another undated Bessemer manual, A Manual on the Care and
Operation of the Bessemer Gas Engine, had this to say about the
company’s cylinders.

‘Cylinder outfits 8, 12 and 15 HP, are used to convert steam
engines of 12-inch stroke into gas engines by replacing the steam
cylinder with a Bessemer gas cylinder of 6-, 7- or 9-inch bore,
12-inch stroke, and using the steam bed cross-head, crank and parts
and substituting a Bessemer clutch for one flywheel.’

The Bessemer parts manual lists the Judson class ‘A’
governor as Bessemer’s standard-issue governor for its

‘Used on open case oil field engines standard for 8, 10 and
12 HP … standard for 20 and 22 HP … standard for 25, 30 and 35
HP engines.’

Many collectors find that oil field engines flood easily if a
rich mixture of gas is used when starting. The operator’s
manual sheds some light on this subject:

‘A gas engine receives its power through the burning of gas
and air in proper proportion. For a given size engine a definite
amount of gas is required, depending on the heating value, rated HP
and the BHP load.

‘The gas system to the engine consists of a regulator, meter
and gas reservoir. From the latter the gas is piped directly to the
governor and thence to the mixing valve on the engine. A
low-pressure regulator with suitable capacity should be placed in
the gas line so that a uniform pressure will be maintained from 6
to 10 ounces. While it is possible to operate the engine on a much
higher pressure, it is not recommended as the danger of choking
while starting is increased.’

People often ask if an accumulator tank in the fuel line helps
an engine run. Bessemer included this type of tank in its
recommendations for fuel connections and offers specifications for
its construction. Remember, however, that requirements for an
engine pulling a full load are much different than an engine idling
for exhibition purposes:

‘The gas reservoir is simply a storage for gas, and should
have a capacity of not less than six times the piston displacement.
The reservoir may be made with a joint of large pipe, air receiver
or any low-pressure container of suitable capacity. Its location
should be as near the engine as possible, and if it cannot be
located within 8 or 10 feet of the engine, use a larger gas line
than corresponds to index stop, between gas reservoir and index
stop, thus reducing the friction loss and maintaining nearly equal
pressure between the engine and reservoir.’

The book goes on to offer further advice for proper mixture
control of Bessemer engines:

‘There is but one adjustment on the mixing valve and that is
the butterfly valve in the air passage. This valve controls the
amount of air in proportion to the amount of gas. There is one
particular setting of this valve, which gives best results for a
certain pressure of gas, and usually it can be found readily with

Bessemer Engine Specifications


Bore & Stroke


Flywheel Dia.

Flywheel weight

Shipping weight


5.5 x 7






6.5 x 9






7.5 x 10






7.5 x 12






8.5 x 15






9.5 x 15






10 x 15






10.5 x 16






11.5 x 16






12 x 16





‘When pulling a full load with a gas pressure from 6 to 8
ounces, this valve should be wide open, and while the performance
of the engine on light loads will be equally as satisfactory with
the same setting, it is advisable to partly close the valve for
continuous light load on account of the slight saving of gas
thereby effected. The saving is due to the lowering of the mean
effective pressure in the charging end of the cylinder caused by
lowering its volumetric efficiency, and at the same time lowering
the transfer pressure.

‘Consequently, the amount that the mean effective pressure
is lowered decreases the negative work and adds just that much to
the effective power of the engine. The approximate closing of the
valve is inversely proportional to the load of the engine, i.e.,
for three-quarters load close the valve one-quarter, for one-half
load close the valve one-half and for one-quarter load close the
valve three-quarters. It must be remembered that when the load is
variable the setting must be for the maximum load, or there will be
danger of stalling the engine.’

The parts manual also has a section on hot-tube ignition:

‘Hot tube igniters are made from either nickel alloy or
wrought iron, having an inside diameter from
5/16-inch to 3/8-inch,
and a length usually within the limits of 6 to 8 inches. In extreme
cases, however, the limits may run from 3 inches to 10 inches. A
long tube causes an earlier ignition than a short tube, when the
inside diameters are the same, or a larger inside diameter tube
causes an earlier ignition than a smaller inside diameter tube of
the same length, so it may require some experimenting to determine
the length of tube that will give the best results.

‘The furnace is an enclosure in which heat is produced for
keeping the tube hot and the performance of the engine depends a
great deal on its condition, as the tube must be kept hot or the
engine will behave badly, backfire, run irregularly and not pull
the load satisfactorily. The inside of the furnace is lined with
asbestos to prevent the heat from escaping through the wall, and
should the lining be wasted to any extent the radiation of heat
through the wall will be so great it will be impossible to keep the
tube hot enough.

‘When adjusting the mixer for the furnace it is very common
for the engineer to watch the flame by looking down into the
furnace while the engine is running. This habit is very dangerous
on account of the possibility of the tube bursting and blowing
either part of the tube or other foreign matter into the eyes and
causing permanent injury. A safe way for making such observances
would be by using a small looking glass.’

I hope everyone will find these recommendations from this
Bessemer operator’s manual helpful. As always, anyone
interested in a free membership to the Oil Field Engine Society
(OFES) should write or e-mail me at the address below.

Contact the Oil Field Engine Society at: 1231 Banta’s
Creek Road, Eaton, OH 45320-9701, online at: www.oilfieldengine.com
or e-mail at: oilengine@voyager.net

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