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A beam-engine is a type of steam engine that features a specific form of construction used primarily in the early stages of steam engine development. This design is now considered obsolete.

Key Features:

  1. Vertical Steam Cylinder: The steam cylinder in a beam engine is oriented vertically. Steam pressure acts on a piston within this cylinder.
  2. Pivoted Beam: A large horizontal beam, often referred to as the “walking beam,” is pivoted at its center. This beam acts as a lever.
  3. Piston Connection: One end of the pivoted beam is connected to the piston rod extending from the steam cylinder. As steam enters the cylinder and moves the piston, this end of the beam moves up and down.
  4. Work Load Connection: The other end of the beam is connected to the work load, which could be a pump rod, a flywheel, or other mechanical components used to perform work, such as driving machinery or lifting water.


  • Steam Admission: Steam is admitted into the cylinder, pushing the piston upwards. This upward motion causes one end of the beam to rise.
  • Beam Movement: As the beam pivots around its central fulcrum, the opposite end of the beam moves downward, transferring the mechanical energy to the connected work load.
  • Exhaust Phase: After the upward stroke, the steam is exhausted, and the piston is pushed back down either by gravity or the return stroke, causing the beam to pivot back, repeating the cycle.

Historical Significance:

  • Early Steam Technology: Beam engines were among the earliest forms of steam engines and played a crucial role during the Industrial Revolution.
  • Pumping Applications: They were particularly common in pumping applications, such as draining mines and supplying water to cities.

Although beam engines are largely obsolete today, replaced by more efficient and compact steam engine designs, they are an important part of the history of engineering and technology. Beam engines demonstrated the practical application of steam power and laid the groundwork for future advancements in mechanical engineering.

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