Mechanical engineering is a very wide discipline. Its breadth is due, in part, from its need to cover the design and manufacture of almost everything in a moving system.
This ranges from a system's smallest components to the completed, sometimes enormous, machine as a whole. Throughout history, some innovations have come to define mechanics and the modern machine, the following inventions are prime examples.
These engineering innovations range from any one of the classical "simple machines" to complex concepts such as flight. This list is far from exhaustive and in no particular order.
1. The Aeolipile was an early steam reaction turbine
The Aeolipile was the world's first rotating steam engine, or more technically correct, a steam reaction turbine. It was devised by the great Heron of Alexandria in the 1st Century AD and described it in great detail in his book Pneumatica.
This relatively simple device works by heating a reservoir of water within the device to generate steam. The steam is then conducted through one of the copper supports to a pivoted brass sphere.
Once the steam reaches the sphere, it escapes through one of two nozzles at the ends of two, small, opposingly pointing arms. The escaping steam generates thrust and causes the sphere to rotate.
The basic principle is simple, but the device’s real genius is that only one of the supporting arms pass steam to the sphere (via a sleeve bearing).
This pushes the sphere against the other, ‘solid’, supporting arm, which also has a thrust bearing. The solid arm includes a conical point that bears against a matching indentation on the surface of the sphere. This combination holds the sphere in place whilst it rotates.
2. Wheel and axle - A powerful simple machine
There are very few innovations in mechanical engineering that have had as much influence as the wheel and axle. The modern world would look very different without them.
The wheel and axle is one of the six simple machines as defined in antiquity and expanded during the Renaissance.
The first depictions of wheeled-vehicles appear on an earthenware Bronocice pot from Poland, and date to around 4000 BC. The pot clearly depicts a wagon of some kind, with four wheels set on two axles.
The earliest actual evidence of a physical wheel-axle combination comes from Slovenia and is dated to around 3360-3030 BC.
The invention of the wheel and axle literally changed the world, and has been an enduring feature of human transport devices for the past 6,000 years, and is likely to remain so well into the future.
3. Windmills began to replace manpower
Windmills are incredibly ingenious devices that are able to convert wind power into useful mechanical work. This is achieved by using large ‘sails’, usually made of wood, to impart a rotational force to the main shaft. This, in turn, can be used to do work, such as grinding flour.
The Persians were some of the first people to harness the power of the wind to do work when they began building early forms of windmills in Iran and Afghanistan in around the 7th Century AD.
These early windmills consisted of sails radiating from a vertical axis within a building, with two large openings for the inlet and outlet of wind, diametrically opposite each other. The mills were used to directly drive single pairs of millstones without the use of gears.
They were one of the first means by which civilizations were able to directly replace human beings with machines as the main source of power.
Windmills would become increasingly widespread throughout Europe during the Middle Ages, and remained in common use well into the 19th Century.
The development of steam power during the industrial revolution would lead to the eventual decline of windmills.
4. Pulleys make lifting things easy
Pulleys are one, or several wheels, on an axle or shaft that support the movement and a change of direction of a cable or belt (that is usually taut). They transfer power between the shaft and cable and provide a mechanical advantage that is ideal for lifting heavy objects.
Pulleys come in various types:
- A fixed pulley has an axle mounted on bearings attached to a support structure
- Movable pulleys have axles mounted on movable blocks.
- Compound pulleys are a mixture of the above two. The perfect example is the block and tackle pulley system.
The pulley was identified by the great Heron of Alexandria as one of the six basic simple machines. Today, pulleys are an integral part of many mechanical systems, including fan belts, flag poles, and water wells.
5. Humankind's obsession with flight shrunk the world
Long before the Wright Brothers were even born, humans have been trying to take to the air. One such lesser-known flight pioneer was Brother Eilmer. Eilmer was a monk from Malmesbury Abbey, England, who made an early attempt at flying in 1010 AD.
An account of the event can be found in William of Malmesbury’s twelfth-century book Gesta Regum Anglorum.
It is said that Brother Eilmer was inspired by the legend of Icarus to build a basic glider and attempt to fly. His glider was built from a wooden frame and either linen or parchment.
He succeeded in launching himself from a height of about 18 meters above ground, and glided for around 200 meters, before subsequently panicking and crashing, breaking both his legs.
Eilmer returned to the drawing board and planned for another flight, only to be stopped by an order from his Abbot against any further attempts.
Brother Eilmer’s desire to fly, like that of others that followed him, from the seventeenth-century Ottoman Hezarfen Ahmed Celebi to the great Leonardo da Vinci, would drive our understanding of flight and aerodynamics.
6. Steel was the precursor to many later mechanical engineering marvels
Steel, an alloy of iron and carbon, has been known since the Iron Age. But for most of this time, the quality of steel produced varied widely.
The first blast furnaces capable of making usable steel began appearing in China around the 6th Century BC and would spread into Europe during the Middle Ages. By the 17th Century steel-making was more or less well-understood, and by the 19th Century production methods and quality were improved dramatically with the development of the Bessemer process.
Early metallurgists realized that when iron gets very hot it begins to absorb carbon. This, in turn, reduces the melting point of iron as a whole and makes the final product brittle.
They soon realized that they needed to find a way of preventing the high carbon contents to make iron products less brittle.
In around 1050 AD the precursor to the modern Bessemer Process was developed. This process decarbonized the metal through repeated forging under a cold blast.
Although this process was far less efficient than Bessemer’s later development, it would form a critical step in the development of the metallurgy of iron and steel.
The most important development was made by Henry Bessemer himself, in 1856. He developed a way of blowing oxygen through molten pig iron to reduce the carbon content relatively cheaply and at scale, thus creating the modern steel industry.
7. Sailing ships open up the oceans
The very first depiction of a sailed ship dates back to around 3300 BC and is found in an Egyptian painting. These early boats featured a square sail as well as banks of oars.
As they were confined to the Nile River and depended on winds within a narrow channel, it was vital to retain oars for use during times of insufficient wind speed.
This combination of sail and oar dominated early ships for centuries, reaching heights of technological advancements with the triremes of the classical period.
Later sails used in Europe were made of woven flax fiber, which is still used today, although it has been largely replaced by cotton.
Sailed ships would enable the long-distance exploration of the seas and open up new trade routes. They would, in effect, shrink the world and allow previously disconnected nations to exchange goods and knowledge.
They would also enable some nations to expand their influence around the world and, in some cases, assist in the creation of an empire.
Trade and empire would provide incentives to further drive advancement in ship technology and mechanical engineering to the present day.
8. The printing press industrialized bookmaking
The printing press was one of the most important inventions in mechanical engineering and for human history. Johannes Gutenberg’s adaptation of the printing press was groundbreaking in its own time and set the stage for enormous advancements in printing made during the Renaissance and Industrial Revolution.
Movable type printing had been around for some time before Gutenberg, notably in China, but his device was the first to mechanize the process of applying text and images to paper en masse.
Gutenberg’s press was modeled on the ancient wine presses of the Mediterranean and was, in fact, made from a modified wine press. It was also designed on the existing presses of the medieval period.
His press worked by rolling ink over a pre-arranged raised surface of movable text held within a wooden frame. This was then pressed against a sheet of paper to create a copy.
This process was vastly more efficient than other presses of the time, not to mention the previous process of hand-copying books.
The press would allow books to be produced more quickly, and, most importantly, more cheaply, enabling more and more people to afford to buy them. This would mark a watershed in human and engineering history.
9. The piston is a vital component of reciprocating engines
The invention of the piston is widely credited to French physicist Denis Papin, in 1690 AD. His design for a steam piston engine was built upon by later inventors like Thomas Newcomen and James Watt during the 18th Century.
Its invention, along with other advancements in steam engine technology, would mark the ‘true’ beginning of the Industrial Revolution.
Pistons are generally contained within a cylinder that is made air-tight by the use of piston rings. In modern engines, the piston serves to transfer force from expanding gas in the cylinder into reciprocating motion on a crankshaft.
This process is effectively reversed when applied to pumps.
Today, pistons are essential components in many reciprocating engines, pumps, compressors, and other similar devices.
10. Levers give you mechanical advantage
"Give me a place to stand, and I shall move the Earth with it," is a remark of Archimedes, who formally stated the correct mathematical principle of levers" - Pappus of Alexandria.
The lever, yet another simple engine, consists of a beam (or rigid rod) that pivots on a fixed hinge or fulcrum. Levers are incredibly useful devices that can provide mechanical advantage to move very heavy objects with relatively little effort, otherwise known as leverage.
Depending on where the fulcrum is located in relation to the load and effort, levers can be divided into three types:
- Class 1 levers are those where the fulcrum is located in the center of the beam. Examples include a seesaw and a crowbar.
- Class 2 levers are those where the load (resistance) is located in the middle. Examples include a wheelbarrow and brake pedal.
- Class 3 levers are those where the effort is located in the middle. Examples include tweezers and the jaw.
Levers are first identified in the works of Archimedes in the 3rd Century BC.
11. The locomotive revolutionized transportation forever
Richard Trevithick, in 1801-1804, built both the first steam carriage and an experimental steam locomotive in Pen-y-Darren, Wales, UK. He later sold the patent, and in 1804 revised his original version to successfully carry 10 tons of iron, 5 wagons, 70 men for about 10 miles. This trip took just over 4 hours, meaning this early locomotive clocked up an under-whelming 2.4 miles per hour. Despite this, it was one of the very first steam locomotives to produce actual practical work.
The locomotive would go on to increase in speed, and to transform the face of industry and transportation the world over.
12. Inclined planes or ramps make lifting easier
The humble yet immensely important ramp, or inclined plane, is another of the fundamental six simple machines and allows heavy loads to be moved vertically with relatively little effort. Ramps are widely used in many applications, from loading goods into trucks to disabled access ramps.
Moving an object up an inclined plane requires less force than lifting it straight up, but at a cost of an increase in the distance moved. The mechanical advantage for ramps is equal to the ratio of the length of the sloped surface to the height it rises.
The screw and wedge are other simple machines that can be considered variations on the inclined plane, rather than discrete forms.
13. Gears and cogwheels transmit torque with ease
Gears or cogwheels are integral components of any rotating machine. They allow for a change in speed, torque, or direction of power. They are some of the most fundamental mechanical engineering innovations in history.
Any change in torque made with the use of gears and cogwheels necessarily creates a mechanical advantage, thanks to the phenomenon of the gear ratio.
A gear can also mesh with a linear toothed part, called a rack, producing translation instead of rotation.
It is unclear exactly when gears and cogwheels were first invented, but some credit Archimedes. Today, gears are present in many moving systems and machines, from bicycles to ship engines.
14. The bearing helps reduce friction
The bearing is another fundamental machine element that has come to define mechanical engineering. These devices allow the constraint of relative motion in one direction or plane while simultaneously reducing friction between moving parts.
Bearings come in many shapes and sizes, and range from components holding shafts or axles in place (plain bearing), to more complex systems like ball bearings.
Sophisticated modern-day bearings often demand the highest level of precision and quality in manufacturing.
15. The wedge is great for breaking things
The wedge is another simple machine and fundamental innovation in mechanical engineering. They have been in use since prehistorical times for activities like splitting logs (axes) or rocks (chisels).
Wedges are defined as movable inclined planes that can be used to separate two objects (or portions thereof), lift objects, or hold objects in place via the application of force to the wide end. The wedge's shape, therefore, converts the input force into perpendicular forces, 90 degrees to the inclined surfaces.
The mechanical advantage achieved by any wedge is dependent on the ratio of its length to thickness. In other words wide, short wedges require more force but produce a quicker result than a long, low-angled wedge.
16. Electrical motors convert electricity into motion
Motors are electronic machines that convert electrical current into rotational movement. Most common electrical motors work through the interaction between a magnetic field and current to generate a force.
The basic principle behind electric motors, Ampere's Force Law, was first described by Ampere in 1820 and was first demonstrated by Michael Faraday in 1821. One of the first practical motors was created by Hungarian physicist, Anyos Jedlik in 1828.
Motors are found in many applications, from industrial fans to power tools, to computer disk drives.
17. Springs are great for storing energy
The spring is simply an elastic object that can store mechanical energy. They tend to be made of steel, and come in many designs, but most commonly in coiled forms.
Whenever a spring is stretched or compressed, it tends to exert an opposing force approximately proportional to its change in length.
Small springs can be made from winding pre-hardened material, while larger springs are usually made from annealed steel that is hardened after production.
In early mechanical history, non-coiled springs, like the bow, were common, but coiled springs began to appear around the 15th Century. Today they have many applications, from vehicle suspension to slinky toys.
18. Parallel motion was first invented in 1784
Parallel motion is a form of mechanical linkage that was first invented by James Watt in 1784. It was developed for use on his double-acting Watt steam engine and replaced the previous Newcomen beam and chain setup.
His new engine design allowed power to be harnessed in both the upward and downward strokes of a piston, effectively doubling the efficiency. It was termed "parallel motion" by Watt because both the piston and the pump rod were required to move vertically, parallel to one another.
It would prove immensely successful and became a critical innovation that helped define mechanics today.
19. Screws convert torque to linear force
Screws are yet another simple machine in use since antiquity. They tend to consist of a cylindrical rod with one or more helical spiraling threads or ridges on the outside.
These ingenious mechanical engineering innovations convert rotational motion into linear force. Screws can also be thought of as a narrow inclined plane, or ramp, that is wrapped around a cylinder.
Famous early examples include the Archimedes screw, which was used as an early form of a water pump.
Screws, like ramps, levers, and pulleys, allow a force to be amplified. In the case of the screw, it provides a mechanical advantage for converting a small torque (rotational force) into a large axial force on a load.
Its mechanical advantage changes depending on the distance between the screw's threads, aka pitch. They are widely used today as fasteners or as basic pumps, presses, and precision devices.
20. The air pump also helped define modern mechanics
The air pump, as the name suggests, is a device for pushing air around. Modern examples include the bicycle pump, gas compressors, air horns, and pipe organs, to name but a few.
The first recorded invention of this device was in 1649 when Otto von Guericke invented the spool vacuum air pump. Today recognized as a type of air pump, his device decreased any potential leaks between the pistons and associated cylinders by using washers made from leather.
The air pump proved to be revolutionary by providing the means for the later development of the vacuum tube which led, in turn, to the development of products like light bulbs. It also helped in the development of pneumatics and of reciprocating pumps.
21. The gas engine was revolutionary
The invention of the gas engine was another innovation that helped define modern mechanics. A form of the internal combustion engine, gas engines can be run using a variety of fuels, such as coal gas, biogas, landfill gas, or natural gas, to name but a few.
Today, gasoline engines can trace their origin to this incredibly important innovation.
Early developments of the technology began in the 19th century, but the first real practical engine was developed by the Belgian engineer Étienne Lenoir in the 1860s. While revolutionary, Lenoir's engine suffered from low power output and high fuel consumption.
Lenoir's pioneering work was further developed by German engineer Nicolaus August Otto, who later developed the first four-stroke engine to efficiently burn fuel directly in a piston chamber.
Without the development of the gasoline engine, the modern world would look very different indeed.
22. The pendulum was another early development in mechanics
The pendulum, which effectively consists of a weight suspended from a pivot of some kind, is another important innovation in mechanical engineering. Thought to have been first developed sometime in the 1st-century, the earliest examples were used as basic seismometers during the Han Dynasty of China.
One of the first recorded uses of a pendulum for time-keeping is said to have been in 10th-century Egypt by the astronomer Ibn Yunus -- although this is disputed. It was during the Renaissance that pendulums began to be used as a kind of power source in manual reciprocating machines like saws, bellows, and pumps.
But it would take the great Galileo Galilei to further develop the pendulum for use in timepieces. He would develop some of the first pendulum clocks.
23. The diesel engine also proved revolutionary
And finally, the invention of the diesel engine was yet another important development for mechanical engineering. Sometimes also called a compression-ignition or CI engine, diesel engines are named for their progenitor, Rudolf Diesel.
A form of an internal combustion engine, diesel engines work by igniting fuel through mechanical compression (adiabatic compression). This is in contrast to gasoline engines, which use a spark plug to ignite an air-fuel mixture.
For this reason, diesel engines have the highest thermal efficiency of any existing practical combustion engine. Rudolf Diesel first conceived of the idea in the late-1870s after attending a lecture by Carl von Linde on the Carnot cycle.
He would later patent his idea in 1893 and the rest, as they say, is history. Today, diesel engines receive a lot of bad press due to their high levels of carbon emissions, and many authorities are in the process of banning them completely.