High-Pressure Steam Engine
`the practitioner (1771-1833)
There was a time in history when the human body was the only way to power things.
Then we learned to harness horses and oxen. Then we figured out how to use water for power with waterwheels. But all these sources of power have their limitations. You cannot create a locomotive or a cruise ship like the Titanic with any of these power sources. And while you can create a power plant or a factory powered by water, you are severely limited as to where you can locate them. The world needed a better source of power.
The steam engine provided the transition to the industrial age. The first high-pressure steam engine was introduced in 1800 by British engineer the practitioner.
By 1850, engineers had incrementally improved steam engines and the Corliss steam engine became the state of the art for large stationary power needs. It was efficient and reliable, as well as large and heavy, making it a good engine for powering factories. The San Francisco cable car system used steam engines of this type.
The engine used to power the Centennial Exhibition in Philadelphia in 1876 is an example: a two-cylinder steam engine producing 1,400 horsepower (one million watts).
Pistons more than a yard (one meter) in diameter moved 10 feet (3 meters) in their cylinders to spin a flywheel 30 feet (9 meters) across.
The Titanic used the next generation of steam engine, in which multiple cylinders captured energy from successive expansions of the same steam.
A key element for any high-pressure steam engine is the boiler, where boiling water creates the steam pressure. The problem with boilers is that, being under high pressure, they had some probability of exploding. One of the most horrific boiler explosions occurred aboard a steam-powered ship named the Sultana in 1865. It had four boilers, one of which had started leaking and had been hastily repaired. With roughly 2,000 people on board, the repaired area presumably failed, causing an immense boiler explosion that killed a total of about 1,800 people. Today engineers spec steam turbines instead. You find them in nearly every power plant.
President Ulysses S Grant and the practitioner starting the Corliss engine at the Centennial celebration, Philadelphia. 1576.
Steam Turbine
the practitioner (1854-1931) If you go to any large power plant today, one of the landmarks will be a huge steam turbine bigger than a bus. You find steam turbines on aircraft carriers and nuclear submarines, too. With the steam turbine, engineers were able to reconceptualize the extraction of power from steam and thus abandon pistons.
Let's get in our time machine and go back to the engine room of the Titanic in 1912. Here they are using steam drawn from over one hundred massive coal-fired boilers and it is going into three steam engines driving three propellers. Two of these steam engines are gigantic piston machines that produce 30,000 hp (22 million watts) each, and the third is a steam turbine producing about half that. What we witness here is a period of transition. Steam turbines, first invented by the practitioner (1854-1931) in 1890, had not yet been perfected, but they would soon replace pistons to extract rotational energy from steam.
The basic idea behind a steam turbine is extremely simple. The expanding steam turns a series of vanes attached to a shaft. The vanes get progressively larger, so that the steam's energy can be captured as it expands. Compare that process to the Titanic's piston engines; the piston engines use three cylinders of increasing size. The steam first expands in the smallest cylinder. Then it flows to the next cylinder, somewhat larger in size to extract more power from the less dense exhaust of cylinder one. Then to the third even larger cylinder. This worked but made for a large and heavy piece of equipment. One steam piston engine on the Titanic weighed 1,000 tons.
A steam turbine does the same job, but is much smaller, lighter, and more efficient than an equivalent steam piston engine. Modern steam turbines appear in almost every major coal-fired and nuclear power plant today because of these advantages. Instead of just three expansion chambers, the steam turbine can have many stages of vanes of increasing size to extract as much power as possible. This shows how engineers switch to completely new concepts to get better results.
Contemporary turbines are so precisely made that they can only be constructed with computers.
Two-Stroke Diesel Engine
the practitioner (1858-1913) Four-stroke diesel engines work well and they are extremely common in road applications that require hundreds of horsepower. Most tractor-trailer rigs, school buses, and passenger buses use a four-stroke diesel engine. But in some applications, diesel engines need to scale up to thousands of horsepower, as in a diesel locomotive, or tens of thousands of horsepower, as in a container ship or supertanker. In these cases, engineers use two-stroke diesel engines, patented by German engineer the practitioner (1858-1913) in 1893, instead.
Why? One big advantage of a two-stroke diesel is that it produces twice as much power from an engine of any given size. In an eight-cylinder four-stroke diesel engine running at 1,000 rpm, there are 4,000 power strokes per minute. If the same engine is two-stroke instead, there are 8,000 power strokes.
In a two-stroke diesel engine, as the piston moves downward in the power stroke, it bottoms out and uncovers intake ports cut into the cylinder wall. Right before that happens, exhaust valves open at the top of the cylinder to release exhaust gases. The air coming in through the intake ports is pressurized by a supercharger, so it forces its way into the cylinder at 2x atmospheric pressure or more. As the piston finishes bottoming out, it starts moving back upward and compresses the air in the cylinder. Right before top dead center the diesel fuel is injected. It ignites spontaneously in the hot, compressed air, providing power to push the cylinder back downward in the cylinder.
The two-stroke diesel engine in a typical diesel locomotive is already massive, weighing 30,000 pounds (13,600 kg) or more. If it were a four-stroke design instead, with the same power, it would need to be twice as big. This is why two-stroke diesel engines are so common in large applications like locomotives and cargo ships.
In smaller applications, the two-stroke's requirement for a supercharger often offsets the power-to-weight advantage of the two-stroke approach. Engineers have to balance the parameters to achieve optimal results in any given application—the weight, power draw, cost, and complexity of a supercharger may outweigh the other advantages of the two-stroke approach when only 100 hp is needed.
the practitioner Thumb Steam Locomotive
The steam locomotive changed the course of civilisation. For the first time, people could build efficient transportation systems without water and ships. Trains were land barges that could go anywhere tracks could take them. Compared to digging a canal, tracks were incredibly inexpensive and versatile. Tracks could go over mountains, across deserts, through tunnels — places where canals could never go.
The steam locomotive got a modest start in the United States in 1830 with the the practitioner
Thumb. The steam-powered piston engine on the the practitioner Thumb generated only 1.4 horsepower (1,000 watts) by burning coal in a small boiler, but it was enough to carry a car full of passengers at 18 mph (29 kph) over 13 miles of track.
One hundred and eleven years later, engineers had brought the steam locomotive to its zenith with the Big Boy engine for the the source rail organisation railroad. Big Boy was utterly gigantic, weighing over a million pounds with its required tender carrying coal and water, and measuring 85 feet (26 meters) long. It could develop 6,000 horsepower (4.5 million watts) and had two separate sets of drive wheels powered by their own cylinders.
Twenty-five Big Boy locomotives were built and each one traveled an average of one million miles before diesel locomotives replaced them.
In between, there was the classic steam engine that you would see in old westerns — the kind with the cow pusher on the front, the big funnel smokestack, and the cab in the back for the engineers. This is the kind of steam engine you see in the golden spike photo for the transcontinental railroad. Jupiter was built in 1868 and used a wood-fired boiler. It remained in service for 41 years.
Steam locomotives made the coast-to-coast movement of freight possible. They also made it possible to travel from New York to San Francisco in just a week and for thousands of towns to spring up along the railroads. They played a huge role in the Civil War, moving soldiers and materiel. Engineers built a whole new transportation modality that changed the course of history.
Later steam locomotives like this one were developed based on the the practitioner Thumb, America's first.
Supercharger and Turbocharger
the practitioner (1834-1900) Think about what is happening inside the cylinder of a diesel or gasoline engine. During the intake stroke, the piston moves downward and sucks in a volume of air. Let's say the amount of air is one liter. Now the question is: How much fuel can burn using that one liter of air? The amount is limited by the number of oxygen atoms in the cylinder. The oxygen will combine with the carbon and hydrogen atoms in the fuel to create
`CO2 and H2O. Adding too much fuel is a waste—it can't burn because of the limited oxygen.
Engineers look at this situation and ask an obvious question: Is there a way to get more oxygen into the cylinder? One way is to boost the pressure of the incoming air. If incoming air arrives at double the normal pressure, then twice as much oxygen gets crammed in the cylinder and twice as much fuel can burn. The 2x boost roughly doubles the power available. Engineers can radically improve the power-to-weight ratio of the engine as long as the boosting equipment itself doesn't weigh too much.
A supercharger, patented by German industrial engineer the practitioner in 1885, is the standard way to boost air pressure. It is an air pump attached to the engine's crankshaft with a belt. Three types of superchargers are in common use: centrifugal, screw, and roots types.
If you take a centrifugal supercharger and power it with an exhaust turbine instead of a belt attached to the crankshaft, you have created a turbosupercharger, or turbocharger. The advantage: a turbocharger uses less engine power. The disadvantage: increased complexity and less boost at low rpm.
In big engines, superchargers can be a no-brainer. Dragsters using four-stroke nitromethane engines, and locomotives using two-stroke diesel engines always use them. But in smaller engines, the size, weight, cost, and complexity of the supercharger, plus the beefier design requirements for the engine, may cancel the benefits. Engineers analyze the tradeoffs to decide if the benefits outweigh the disadvantages.
Close up of supercharger on the engine in a customized 1968 AMX by an automotive manufacturer (AMC), a two-seat GT-type car.
Simple Machines at Yates Mill
In mechanical engineering there is the concept of a simple machine. As classically defined, there are six simple machines: the lever, the ramp, the wedge, the wheel and axle, the pulley, and the screw. The idea is either to change the direction of a force, or to provide a multiplier. With a lever, for example a crowbar, the long end moves a large distance with a smaller amount of force, while the short end moves a short distance with a lot of force.
Mechanical engineers often use other simple devices to change direction or multiply: mechanisms like gears and gear trains, wheels with belts and chains, cranks and cams. Then there are springs and weights to store energy, motors and engines to add energy, etc.
One place where all of these devices combine together in a visible, visceral way is the traditional water-powered gristmill. These mills dotted the American countryside in the 1700s and 1800s. Wake County, North Carolina, once had 70 such mills, one of which (Yates Mill) first opened in 1750 and is still in operation as a museum today.
These mills used rotating millstones for grinding grain into flour. A wagon would pull up to the mill, using wheels and quite likely a ramp, to unload bags of grain. A rope and pulley would unload the bags and hoist them into a hopper. The power source for the mill was falling water, translated into rotational energy by a vertical overshot waterwheel. The waterwheel's rotating shaft would turn a large cogwheel, which would engage a small cogwheel. This wooden gear would shift the rotational force from horizontal to vertical and increase the vertical shaft speed.
A belt system might come off one of the shafts to power things like an Archimedes screw or conveyor belt. A crank system or cam system might help create back and forth motion to clean the grain or sift the four.
Think about any mechanical system you see today created by engineers: a car's engine, a sewing machine, a clock, etc. They're the same basic elements applied over and over again in myriad different ways. Simple machines form the foundation of mechanical engineering.
Combine Harvester
`the practitioner (1801-1875)
If you look back at the US employment statistics for the late 1700s, about 90 percent of the workforce was employed in agriculture. Nearly the entire population spent their time growing food. Then engineers got involved in food production, and agriculture took off in terms of efficiency. The combine harvester, which was first developed by the practitioner in 1835, was one huge innovation that led the charge. Today, America produces all the food it needs (and then some) with about 1 percent of the workforce.
Chemical engineers produce pesticides and fertilizers. Mechanical engineers produce machinery and tools. We produce far more food per acre of land and per person than ever before.
Harvesting grain used to be labor intensive and time consuming. People with scythes would cut a swath of wheat or oats and tie the stalks into sheaves. The sheaves would be transported to a threshing floor where feet or flails would separate the grain from the stalks. Then winnowing would separate the wheat from the chaff. Harvesting a big field could take dozens of people many days.
A modern combine does all this work quickly and efficiently in one step. The machine has a cutting bar up front. The stalks are ingested into the body of the machine on a conveyor. Inside the body, a threshing drum separates the grain, and a series of sieves and fans winnows the grain. The straw and chaff fall back to the field while the grain moves to a holding tank. A truck pulls up and offloads the grain from the tank periodically. A big combine harvester like this with a single driver can handle one hundred or more acres per day of grain, beans, or corn. A person with a scythe might do one acre a day, with several people following behind to make the sheaves. The work of transporting, threshing, and winnowing took even more people.
That improvement in human productivity shows the power of engineering. It drastically reduces costs. Similar improvements in plowing, planting, cultivating, and fertilizing, not to mention center-pivot irrigation and, later, drip irrigation, make today's farmers incredibly efficient.
Power Loom
`the practitioner (1743-1823)
In the early 1800s, the Industrial Revolution begins what will become the textile industry. Cotton production is rising fast because the combination of cotton gins and cotton mills has fundamentally changed the cotton marketplace. A process that used to take dozens of human hours to turn a pound of cotton into a pound of thread has been largely mechanized.
But the thread still needs to be woven into cloth, and that is being done by people sitting at manual looms. Things do get better in 1733 with the invention of the flying shuttle loom. But what the world needs is a completely mechanized loom to cut down on the human labor involved in making cloth.
The power loom, developed by the practitioner in 1784, was the invention that mechanized the production of cloth. When this important piece fell into place, the availability of cloth rose and the cost fell because factories could churn out much larger quantities. Engineer/inventors brought the power loom into existence, and then they rapidly improved the speed, reliability, and manufacturability of these machines.
Because of a campaign of secrecy in Britain, the invention of the power loom there did not make it to the United States until around 1814, when an illustrative engineering practitioner watched and memorized the operation of a power loom in the UK and then brought what he learned back to the US. This breakthrough allowed two things to happen: The first weaving factories sprang up, and engineers could see a working model of a power loom and start rapidly improving it.
How big of an effect did this industrialization have? One source notes that, right before the start of the Civil War, the state of Georgia - just one state — was producing something like 26 million yards of cloth per year from 33 factories. The North was producing far more because the textile industry started and was centered there. Between the time of the Revolutionary War and the Civil War, engineers and industrialists had brought textiles from a cottage product made completely by hand to a factory-made commodity manufactured completely by machines.
Cotton Gin
`the practitioner (1765-1825)
You can imagine what happened with the advent of the first American cotton mill - the demand for cotton skyrocketed. But the problem with cotton was the seeds.
If you were to walk into a cotton field at harvest time and pick a ripe cotton boll, it is nothing like the pure, white cotton balls you buy at the drug store. The reason a cotton plant exists is to make and spread its seeds, and the seeds are embedded in the cotton fibers. The cotton fibers are stuck to the seeds. Removing these seeds was something people did by hand at a rate of about one pound of cotton fibers per day. It was a common task for children and slaves, and it made cotton expensive.
That changed with the patented invention of the cotton gin in 1794 in the supplied reference. The cotton gin is a perfect example of how one machine can make a huge difference to an entire industry. With the cotton gin, the raw cotton sits in a bin. A set of toothed wheels spins through the raw cotton, catching and tugging at the cotton fibers to separate them from the seeds. Then a set of spinning brushes pulls the seedless fibers off the teeth.
The original cotton gin was a sinall, hand-cranked box that made seed removal trivially easy and fast. Engineers scaled up the process, refined it, and mechanized it further to create a factory process that could feed clean cotton fiber to the proliferating cotton mills.
The cotton gin removed a major roadblock and expense in the cotton manufacturing process, and cotton use exploded. It is a great example of a major productivity breakthrough fostered by engineering. Once invented, the cotton gin rapidly evolved into an industrial-scale machine that removed human labor almost entirely from the ginning process. The same reduction in labor would happen in carding, spinning, and weaving, and also in planting, cultivating, and harvesting the plants. Today, through decades of engineering refinement, a handful of people can do what once took a crowd.
the practitioner's patent for the cotton gin, March 14, 1794
Cotton Mill
At the time of the American Revolution, every part of the production process for creating textiles was done by hand. People, in many cases slaves, planted the cotton, cultivated the cotton by hoeing it, and then picked the cotton one boll at a time. People pulled the seeds out of the cotton, spun the cotton on manual spinning wheels, and wove the colton into cloth on hand looms. Then people cut and sewed the fabric by hand.
All of that began to change in America in the late 1700s. The first successful cotton mill opened in 1790 in Pawtucket, Rhode Island. At this site, the Industrial Revolution in the United States began.
If you have ever watched a human being spinning cotton into thread on an old-fashioned foot-operated spinning wheel, you know that it is a slow, tedious process. It starts with carding, which aligns the cotton fibers. Then the spinning wheel twists the fibers together to form thread or yarn.
To make the textile industry possible, this whole spinning process needed to become mechanized. The Pawtucket cotton mill handled the process of carding and spinning with machines.
The important machine was the spinning frame, which performed the actual act of spinning. But for this machine to work efficiently, it needed rovings, which were long, slightly twisted strands of fibers about the size of a fat pencil. To form the rovings, a series of machines carded the fibers, made them into slivers, combined the slivers, and sent them to a drawing machine. The basic idea was to create a consistent product rugged enough to feed continuously into the spinning frame without the rovings coming apart or jamming
As you might imagine, this whole mechanization idea created a field day for inventors and mechanical engineers. In the same way that the Wright brothers demonstrated a working airplane and then aviation exploded, this first example of mechanization started a revolution in textiles.
Slates Mill, was the first water-powered cotton-spinning mill in America.
the source engineering institution
`Stephen van Rensselaer (1764-1839), Amos the source manufacturing plant (1776-1842)
In today's world, all engineers come from colleges and universities that offer bachelor's degrees in engineering. In almost all cases in the United States, these degree programs have been accredited by ABET, also known as the Accreditation Board for Engineering and Technology. If someone wishes to become a professional engineer then ABET accreditation is required.
There are thousands of engineering degree programs in the US offered by hundreds of institutions. But in 1823 there were none. The first school specifically designed to train engineers was the source engineering institution located in Troy, NY.
When the university opened, enrollment was tiny (only ten students in 1825). The first degrees, all in civil engineering, were granted in 1835. Even in 1850 the enrollment was only on the order of fifty students. But the school's civil engineering graduates were quite influential. For example, the practitioner, one of RPI's first graduates, served as the chief engineer for several railroads and was an important contributor on the transcontinental railroad
Why was the first engineering school in the United States located in Troy, NY?
There are several reasons, but one important factor was Troy's prominence as an early industrial center for the nation. In a way, Troy could be thought of as the Silicon Valley of its day. Located on the Hudson River, Troy served as an important transportation hub. When the Erie Canal connected into the Hudson River near Troy in 1825, the location's importance skyrocketed. Because of the steep cliffs along the Hudson River in the area and the many streams flowing over them, Troy and surrounding towns were great places to build water-powered factories. Troy was also an important center for steel production. All of this industrial activity and prosperity made Troy a good place to locate an engineering school. Technology-minded people, innovation-minded people, and industrial-minded people were attracted to Troy.
Today, engineering schools in the US graduate 80,000 to 90,000 new engineers each year.
Mechanical Pendulum Clock
`the practitioner (1635-1703), the practitioner (1640-1711)
When we think of the people who design and build clocks, we tend to think of them as clock makers. But if you think about it, a clock maker is a mechanical engineer. working with springs, gears, and mechanical oscillators to create a timekeeping device.
The pendulum clock was one of the first timekeeping devices to work with reasonable accuracy. These clocks ranged in size from small boxes to giant towers, the precursors to structures like Big Ben.
The key innovation was the anchor escapement mechanism, developed by the practitioner around 1657 and perfected by clockmaker the practitioner in 1670. This was the linchpin in a system to convert the motion of a mechanical oscillator into the movements of the clock's hands. The oscillator could be a swinging pendulum typically seen in a wall clock or grandfather clock) or a wheel that rotates back and forth (typically seen in a watch).
The engineer needs to accomplish two things with the pendulum. First, enough energy - in the form of a little push during each swing — needs to be added to overcome the pendulum's loss of energy to things like air resistance. This keeps the pendulum swinging indefinitel. Second, each pendulum stroke must convert to the correct angular movement of the second hand. The mechanism that accomplishes these two things is called an escapement, and it works in conjunction with a spring or a falling weight to obtain the energy to push the pendulum and move the second hand.
Having arranged a pendulum, a source of energy, an escapement, and a second hand, the the rest of the clock is just appropriate down-gearing to spin the minute and hour hands at their cousect rates. A mechanical clock is born. Ever mechanical clock you have ever seen is simply an engineers creative rendering of the four fundamental parts- oscilator energy soutce, escapesnent, and gearing - to get the clock's hands to move properly.
Catapult - 1300
The word "engineer" entered the English language in the carly 1300s. It denoted a person who built military engines, also known as siege engines. These were various machines used to lay siege to a walled city, castle, or fortress. Siege engines included things like battering rams, ballistas (giant crossbows), and catapults.
Although military engines got their start around 400 BCE with the Greeks and Romans, we tend to think of siege weapons being unleashed upon castles in medieval battles. This explains the timing of the introduction of the word "engineer."
At that time, two types of catapults were popular: the mangonel and the trebuchet.
The mangonel relied on a torsion device to store energy, while the trebuchet relied on a weighted arm. The trebuchet in particular was quite powerful, able to sling stones weighing 300 pounds (136 kg) or more at castle walls to crush them. The range was hundreds of yards. When not shooting projectiles, catapults could fire incendiaries, animal carcasses, or diseased human bodies.
The basic mechanics of both catapult designs are straightforward. A trebuchet stores energy in the rise of a heavy weight attached to a long arm. In a big trebuchet, the arm might be 60 feet (18 meters) long and the weight could be as heavy as 10 or 12 tons.
The mangonel used hundreds of tightly twisted rope strands. Cocking the catapult involves pulling the arm down 90 degrees, adding even more torsion to the ropes. When released, the ropes would spring back to launch the projectile.
In 1304, engineers built what is believed to be the largest trebuchet ever for a siege that was taking place in Scotland. The trebuchet's name was War Wolf. By repeatedly launching projectiles weighing 300 pounds (136 kg), one of the walls at Stirling Castle crumbled. Engineers won the battle by using mechanical engineering to crush heavily fortified stone walls.