Description of the Newcomen Steam engine
The Newcomen atmospheric engine and subsequent beam engines had as a highly visible and characteristic component a beam rocking around in a vertical plane. The beam continued to be a defining element of steam engine architecture for many years, persisting as a central and recognizable part of the engine's overall configuration. Its conspicuous position and role in power transmission made the beam a quintessential characteristic of these early steam engines, which continued to employ this distinctive design long after their initial development.
The following description of a Newcomen atmospheric engine primarily adheres to Tredgold's [1] terminology, while incorporating enhancements to improve clarity and comprehensiveness. To align with modern patent standards and provide a more detailed account, I have supplemented Tredgold's original description with additional details visible in the drawing but not explicitly mentioned in his text. For example Tredgold did not discuss the essential importance of the beam, which was an essential design criteria of the Newcomen atmospheric engine..
To avoid ambiguity, as you should always strive for in a patent specification, disambiguating terms have been introduced for components sharing the same name but serving different purposes, such as the various types of cocks used in the engine.
Begin of patent style type description
The description that follows includes references to directional terms such as "upper" and "lower" in relation to the components of the engine. It is important to note that these directional indications are provided solely as examples, based on the specific orientation depicted in the accompanying drawing.
Individuals skilled in the art will recognize that the orientation of the engine and its components may vary depending on the particular application or installation. The principles and functionality described herein remain applicable regardless of the specific orientation or positioning of the engine or its constituent parts.
When considering the practical implementation of this engine design, the person skilled in the art will understand that the orientation of the components, including the cylinder, piston, and other elements, can be adjusted to suit the requirements of the installation site or the specific needs of the application. The key aspects of the engine's operation and the interrelationship between its components are not dependent on a single, fixed orientation. [2]
In one aspect of the invention, the fire engine comprises a cylinder C with a hollow interior. The cylinder C is designed with a substantially closed base on one end and an open base on the opposite end, allowing a piston P to be inserted into the hollow interior. The piston P functionally divides the cylinder's hollow interior from the surrounding atmosphere thus creating what is referred to in the following as a working chamber. The working chamber thus is confined by the piston P, the closed base and a cylinder wall between the closed base and the piston P.
The piston P is allowed to move axially within the cylinder, adjusting the volume of the working chamber. When a vacuum, is generated within the working chamber, atmospheric pressure forces the piston toward the closed base, performing what is referred to in the following as a power stroke. This movement can be harnessed to perform work. Upon releasing the vacuum, the working chamber can expand, enabling the piston to move axially outward.
In another aspect of the invention a beam is mounted on a central pivot point, allowing the beam to rock back and forth, converting the piston's reciprocating motion into a rocking motion. In addition to the central pivot, the beam may be further supported by vertical structures, such as masonry walls or sturdy timber frames. These vertical supports may stabilize the beam and maintaining its proper alignment within the engine's overall assembly.
In some instances, the beam may be mounted on a masonry wall. This wall, may be part of a larger building structure, serving to accommodate the boiler and cylinder. Such a building structure helps to protect the engine components from the elements, allowing one half of the beam extending into the exterior of the building.
The combination of the central pivot point and the vertical supports forms a robust and reliable system for securely mounting the heavy, rocking beam and may be essential for the efficient and long-lasting operation of the engine, allowing the beam to effectively transmit power while maintaining its structural integrity over extended periods of use.
The beam serves several crucial purposes. The beam acts as a large lever, transferring the reciprocating motion of the piston to the device that is operated by the engine. The beam converts the vertical motion of the piston into a rocking motion that could be used to drive various mechanisms, such as water pumps or ventilation devices. The beam's mass and momentum help to smooth out the engine's operation, providing a more consistent motion despite the intermittent power strokes of the piston. The beam further may help to balance the weight of the piston and pump rods, making the engine's operation more efficient and reducing stress on individual components.
An additional option of the beam is to transfer motion to other parts of the engine thus allowing for the connection of various engine components at different points. For example, it could connect the piston at one end, the pump rod at the other, and additional mechanisms like a small pump to fill water cisterns above the level of the piston.
In an embodiment of the invention a boiler B with its furnace produces steam. A small steam pipe S establishes a fluid communication between the boiler B and a bottom of a cylinder C. A plate p, known as the regulator or steam cock, closes the lower aperture of the small steam pipe S. This plate p rotates horizontally on an axis that passes through the top of the boiler B and is operated by a handle to open or close the fluid communication between the boiler B and the part of the cylinder C beneath the piston P.
A packing with a circular edge made of soft rope, thoroughly imbued with tallow to reduce friction, secures the piston P to the cylinder, ensuring an airtight fit. The upper surface of the packing is kept moist to maintain the steam-tightness of the piston P. A working beam, that rotates the gudgeon G, connects to the piston P via a piston rod A, which is suspended by a piston side chain from a piston side top extremity D of the beam’s piston side arched head.
At the opposite end of the beam, a similar arched head E accommodates a pump rod H operating pumps that draw water from the mine. When the depth of the water makes the steam piston P too heavy to be effective, counterpoise weights I must be added to the pump rod H until the piston rises in the steam cylinder at the appropriate speed.
An injection cistern L, fed by a forcing pump R, is located at a certain height above the top of the cylinder. From the cistern L, an injection pipe M descends descends to the bottom of cylinder C and entering the cylinder C terminating inside the cylinder C at a point N, with one or more tiny holes. An injection cock, equipped with a handle, is inserted into the injection pipe M to control water flow from the injection cistern L into the cylinder C. A snifting valve V, named for the sniffling noise it makes when air is expelled, has a small dish to contain water and ensure an airtight seal.
Additionally, a pipe (Q) emerges from the bottom of the cylinder , known as the eduction pipe. Its lower end, submerged in a water cistern U called the hot well, allows condensed water to drain by gravity upon steam re-admission. The eduction pipe turns upward and is covered with a valve v to prevent backflow when the vacuum reforms. The boiler has a safety valve T to control steam pressure, loaded to a maximum of one or two pounds per square inch (0.07-0.14 atm).
An operator has to follow the following steps:
- Heat the boiler until steam escapes from the safety valve.
- Open the steam regulator to allow steam to enter the cylinder C. The counterweight at the opposite end of the beam, causes the piston P to rise and the pump rod H to descend.
- When the piston P reaches the top of the cylinder C, close the steam regulator and open the injection cock. This introduces cold water into the cylinder, condensing the steam and creating a partial vacuum.
- The piston P then descends under atmospheric pressure, driving the pump rod H up and lifting water from the mine.
- As the piston P descends, air introduced by the steam and injection water is expelled through the snifting valve.
- The injection water drains out through the eduction pipe.
The cycle 2 - 6 of steam admission and water injection is repeated to continuously pump water from the mine
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[1] Thomas Tredgold, The Steam Engine, Vol. I, London, 1838
[2] It is a common practice in patent descriptions to include remarks about the use of directional terms, such as "left," "right," "upper," "lower," "behind," "in front," and so on. This is done to avoid potential limitations in the interpretation of the patent claims during litigation.
These early steam engines were typically used only in the standard upright configuration for an astonishingly long time. It wasn't until approximately 80 years later that Edward Bull conceived the idea of inverting the orientation of the piston. By allowing atmospheric pressure to push the piston upward when a vacuum was created in the cylinder, this new configuration enabled the cylinder to be mounted directly above the pump shaft. As a result, the pump rod could be directly driven by the piston rod without the need for a beam mechanism. However, it is advisable to exercise caution and avoid language that might unnecessarily limit the scope of a patent.
It is therefore considered good practice to use more generic, functional descriptions when referring to the various components and their relative positions. For example, instead of using terms like "left" or "right," it would be preferable to use expressions such as "piston-side" and "load-side" to distinguish between the elements connected to the piston and those on the opposite half of the beam.
This approach would have helped to maintain a broader, more adaptable perspective, should future iterations or alternative designs of the atmospheric engine require different orientations or configurations. By focusing on the functional relationships between components rather than their specific spatial arrangements, the description can remain applicable to a wider range of potential implementations.
While the traditional upright orientation may have been the predominant configuration for Newcomen engines, acknowledging the possibility of alternative arrangements, even if unlikely, can contribute to a more comprehensive and flexible understanding of the engine's design principles and potential applications.
last review 15/04/2025