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Bessemer by the Book

Bessemer-Duplicate Parts

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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 engines.

'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 experience.

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