A beam engine is a type of steam engine in which a rotating head beam is used to apply the force of a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall. Engine efficiency was improved by engineers including James Watt who added a separate condenser, Jonathan Hornblower and Arthur Woolf who composed the cylinders, and William McNaught (Glasgow) who devised a method of composing an existing engine. Beam engines were first used to pump water from the mines or into the canals, but could be used to pump water to supplement the flow of a hydraulic wheel feeding a mill.
The first beam motors were powered by water, and are used to pump water from the mines. A canned example can be seen at Wanlockhead in Scotland. Beam engines were widely used to pump bombs into the English Channel system when it was expanded by locks at the beginning of the Industrial Revolution and also to drain the water from the mines in the same period and as sinuous engines.
The first steam-related beam motor was developed by Thomas Newcomen. This was not, properly speaking, powered by steam, as the steam introduced under the piston was condensed to create a partial vacuum thus allowing atmospheric pressure to push the piston down. Therefore, it was called an atmospheric engine. Newcomen's atmospheric engine was adopted by many mines in Cornwall and elsewhere, but was relatively inefficient and consumed a large amount of fuel. The engine was upgraded by John Smeaton, but James Watt solved the major inefficiencies of the Newcomen engine in its Watt steam engine by adding a separate condenser, thus allowing the cylinder to remain hot. Technically this remained an atmospheric engine until (under subsequent patents) it enclosed the top of the cylinder, introducing the steam to also push the piston down. This made him a true steam engine and possibly confirms him as the inventor of the steam engine. He also patented the centrifugal regulator and parallel motion. The latter allowed the replacement of chains around an archhead and allowed its use as a rotary engine.
Their patents remained in place until the beginning of the nineteenth century and some say that this hindered development. However, in reality the development had been permanent for others and at the end of the patent period there was an explosion of new ideas and improvements. Watt beam motors were used commercially in much larger quantities and many continued to run for 100 years or more.
Watt had patents on key aspects of the design of his engine, but his rotary engine was equally restricted by the patent of a simple crank. The beam motor expanded considerably in the areas rich in tin and copper from the southwest of England, which allowed the drainage of the deep mines that existed there. Therefore, Cornwall beam engines became world famous, as they remain among the largest ever beam engines ever built.
It can be understood in the following video:
