Beam engine

A beam engine is a design of engine based on the principles of a first-class lever. A force is applied to one end of a beam, which is pivoted in the middle, and the lever action transfers the force to create work at the other end of the beam.

The most familiar example is the type of stationary steam engine used for pumping water from mines. Here the piston of a vertically-mounted cylinder is attached to one end of the beam, to apply the force through upward and/or downward motion. The other end of the beam is connected to a vertically-acting pump. A downward pull on the piston causes the other end of the beam to lift whatever is attached to it, thereby doing 'work'.

The most common engine was the stationary steam-driven type, but water, wind or other forms of propulsion could be used.

Beam engines need not be 'stationary'. The steamboat Eureka is still powered by its rotative beam engine.

History

The first beam engines were water-powered, and used to pump water from mines. A 'preserved' example may be seen at Wanlockhead, in Scotland.

Beam engines were extensively used to power pumps on the English canal system when it was expanded by means of locks early in the Industrial Revolution, and also to drain water from mines in the same period, and as winding engines.

The first steam-powered beam engine was developed by Thomas Newcomen. The Newcomen steam engine was adopted by many mines in Cornwall and elsewhere, but it was relatively inefficient and consumed a large quantity of fuel. James Watt resolved the main inefficiencies of the Newcomen engine in his Watt steam engine, and these beam engines were used commercially in much larger numbers.

Watt held patents on key aspects of his engine's design, and it was not until these patents expired that others could develop modifications to improve it. The beam engine was considerably improved and enlarged in the tin- and copper-rich areas of south west England, which enabled the draining of the deep mines that existed there. Consequently the Cornish beam engines became world famous, as they remain the most massive beam engines ever constructed.

Rotative beam engines

In a rotative beam engine, the piston is mounted vertically, and the piston rod does not connect directly to the connecting rod, but instead to a rocker or "beam" above both the piston and flywheel. The beam is pivoted in the middle, with the cylinder on one side and the flywheel, which incorporates the crank, on the other. The connecting rod connects to the opposite end of the beam to the piston rod, and then to the flywheel.

Early Watt engines used Watt's patent sun and planet gear, rather than a simple crank, as use of the latter was protected by a patent owned by someone else. Once the patent had expired, the simple crank was employed universally.

See also

* Stationary engine
* Steam engine
* Cornish engine
* Man engine
* Mining in Cornwall
* Prestongrange Industrial Heritage Museum

Preserved beam engines

* Bolton Steam Museum – "includes several rotative beam engines originally used to drive mills"
* Crofton Pumping Station – "two engines, including the oldest working 'Cornish' engine, in its original location, in the world (1812)"
* Crossness Pumping Station – "set of four rotative beam engines: the largest surviving working examples"
* Museum De Cruquius – "the eight-beamed engine at Cruquius is thought to be the largest steam engine ever built"
* Elsecar – "the only surviving Newcomen engine (in the world) to have remained in its original location (1795)"
* Kew Bridge Steam Museum – "four 'Cornish' engines (in original location) and several rotative engines (in museum):
includes largest working 'Cornish' engine in the world"
* Markfield Beam Engine – "a compound, rotative engine"
* Smethwick Engine – "oldest working steam engine in the world (1779)"
* The Western Springs Water Works, Auckland, New Zealand - "1877 double Woolf compound engine"

External links

* [http://www.keveney.com/watt.html Animation] of a Watt beam engine.
* [http://www.cornishlight.co.uk/levant.htm The oldest surviving mine engine] in Cornwall.