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Crane: When We Think It Can't Be Lifted - History Documentary Films

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Crane: When We Think It Can't Be Lifted - History Documentary Films WATCH MORE ON NETFLIX : GET 1 YEAR FREE ACCESS CLICK HERE: https://fastfilez.com/asDZ A crane is a kind of machine, normally equipped with a hoist, wire ropes or chains, and sheaves, that could be used both to lift and lower products and to move them flat.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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by Chris Woodford. Last updated: November 3, 2021.

Have you ever tried pedaling a bicycle up a really steep hill? It's pretty much impossible unless you use the right gear to increase your climbing force. Once you're back on the straight, it's a different story. Flick to a different gear and you can go incredibly fast: you can magically make your wheels turn round much faster than you're pedaling. Gears are helpful in machines of all kinds, not just cars and cycles. They're a simple way to generate more speed or force or send the force of a machine off in another direction. In science, we say gears are simple machines.

Photo: Typical machine gears. An opened-up gearbox on show at Think Tank, the science museum in Birmingham, England. In a car or a motorcycle, the gears "mesh" so the teeth of one wheel lock into the teeth of another; that stops them slipping, which means power is transmitted more smoothly and efficiently. In a bicycle, the gears don't link by meshing together directly. Instead, a lubricated chain connects together the gears (known as sprockets) on the wheel you pedal with those on the back wheel. That's simply because the pedal wheel and the back wheel are some distance apart and a chain is the easiest way to link them together.

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What do gears do... and how do they do it?

Gears are used for transmitting power from one part of a machine to another. In a bicycle, for example, it's gears (with the help of a chain) that take power from the pedals to the back wheel. Similarly, in a car, gears transmit power from the crankshaft (the rotating axle that takes power from the engine) to the driveshaft running under the car that ultimately powers the wheels.

You can have any number of gears connected together and they can be in different shapes and sizes. Each time you pass power from one gear wheel to another, you can do one of three things:

How do they do it?

Gears sound like magic, but they're simply science in action! Look at the diagram here and you'll see exactly how they work. The pair of gear wheels (top) works in exactly the same way as an ordinary pair of wheels the same size that are touching (middle); the only difference is that the gears have teeth cut around the edge to stop them slipping. But a wheel is really just a lever, so a pair of wheels that touch is like a pair of levers that touch (bottom).

Thinking of gears as levers shows exactly how they work. Suppose you turn the axle at point (1). The bar connecting points (1) and (2) moves faster and with less force at point (2) because it's working as a lever. If you can't see this, suppose the red bar were a spanner and you pushed at point (2) to undo a nut at point (1) in the center. Then point (1) would turn with less speed and more force. If you turn at point (1) instead, the opposite is true: you get more speed and less force at point (2). That's the red bar, which is just touching the blue bar. As the two bars touch, they must be going at the same speed. Now the blue bar is also a lever, but it's working the other way: like a spanner. So if we apply a force at point (2), it's magnified by the leverage of the blue bar and we get more force (and less speed) at point (3).

Putting everything together, what do we get? We apply a certain force and speed at point (1). The red bar might give us four times the speed and a quarter of the force at point (2). But the blue bar will work the other way and maybe halve the speed and double the force. So when we get to point (3), we have twice the speed and half the force that we had at point (1). That's what we'd expect from a pair of gear wheels where one (red) is twice the size and has twice as many teeth as the other (blue).

Photo: In an egg whisk, gears help to make light work of mixing in two different ways-by increasing speed and changing direction. When you crank the handle, you turn the large outer gear wheel at moderate speed. This large wheel meshes with a pair of small gear wheels fitted to the top of the two axles attached to the blades. Each rotation of the large wheel (blue) makes the smaller wheels turn round several times (red), giving a dramatic increase in speed at the blades. The gears also help by changing the direction of rotation: you crank the handle about a horizontal axis, but the two whisk blades turn about a vertical axis.

Why do we need gears?

Let's think about cars. A car has a whole box full of gears-the gearbox-sitting between the crankshaft and the driveshaft. But what do they actually do?

A car engine makes power in a fairly violent way by harnessing the energy locked in gasoline. It works efficiently only when the pistons in the cylinders are pumping up and down at high speeds-about 10-20 times a second. Even when the car is simply idling by the roadside, the pistons still need to push up and down roughly 1000 times a minute or the engine will cut out. In other words, the engine has a minimum speed at which it works best of about 1000 rpm. But that creates an immediate problem because if the engine were connected directly to the wheels, they'd have a minimum speed of 1000 rpm as well-which corresponds to roughly 120km/h or 75mph. Put it another way, if you switched on the ignition in a car like this, your wheels would instantly turn at 75mph! Suppose you put your foot down until the rev counter reached 7000 rpm. Now the wheels should be turning round about seven times faster and you'd be going at 840 km/h or about 525 mph!

It sounds wildly exciting, but there's a snag. It takes a massive amount of force to get a car moving from a standstill and an engine that tries to go at top speed, right from the word go, won't generate enough force to do it. That's why cars need gearboxes. To begin with, a car needs a huge amount of force and very little speed to get it moving, so the driver uses a low gear. In effect, the gearbox is reducing the speed of the engine greatly but increasing its force in the same proportion to get the car moving. Once the car's going, the driver switches to a higher gear. More of the engine's power switches to making speed-and the car goes faster.

Changing gears

Photo: Bicycle gears: Bikes have two sets of different-sized gears on the wheel you pedal and the back wheel. Instead of touching directly and rotating in opposite directions, each pair of gear wheels is connected by a flexible metal chain (kept taught by a springy lever and gear-shifting mechanism called a derailleur), so they turn in the same direction; technically, gears linked this way are called sprockets. When you change gear, you shift the chain from one pair of sprockets to another. For cycling at speed, you'll use a larger sprocket on the pedal wheel than on the back wheel.

In theory, changing gears is about using the engine's power in different ways to match changing driving conditions. The driver uses the gearshift to make the engine generate more force or more speed depending on whether hill-climbing power, acceleration from a standstill, or pure speed is needed. In practice, changing gears means meshing different sized gear wheels together, but you can't do that while the gearbox is transmitting power from the engine at high speed. That's why you need to press a car's clutch pedal before changing gears, which disengages the engine's input from the gearbox. You can then use the gearshift to change to a different pattern of gears, before letting the clutch transmit power back from the engine to the gearbox (and the wheels) once again.

On a bicycle, it's much more obvious what's going on when you change gears because you can see it happening. As you flick the gear shift, you can watch (and feel) the chain hop from one sprocket to another, engaging different-sized gear wheels. On many bikes, the gear change is controlled by a clever mechanism called a derailleur, which smoothly diverts the chain from sprocket to sprocket even though you're pedaling along at speed.

Six different ways to use gears

I've made some simple gear machines with an old construction set to illustrate a few of the ways in which we can use gears to do different jobs:

Gears for speed

In this simple gearbox, I've got (from right to left) a large gear wheel with 40 teeth, a medium wheel with 20 teeth, and a small wheel with 10 teeth. When I turn the large wheel round once, the medium wheel has to turn twice to keep up. Similarly, when the medium wheel turns once, the small wheel has to turn twice to keep up. So, when I turn the large gear wheel on the right, the small wheel on the left turns four times faster but with one quarter as much turning force. This gearbox is designed for increasing speed.

Gears for force

If I power the same gearbox in the opposite direction, by turning the small wheel, I'll make the large wheel spin a quarter as fast but with four times as much force. That's useful if I need to make a heavy truck go up a hill, for example.

Worm gears

Here I'm using an electric motor (the gray box on the right) and a long screw-like gear (called a worm) to drive a large gear wheel (known as a worm wheel). This arrangement is called a worm gear or worm drive. It reduces the speed of the motor to make the large wheel turn with more force, but it's also useful for changing the direction of rotation in gear-driven machinery. It does the same job as a normal pair of gear wheels but takes up much less space.

Rack and pinion gears

You've probably seen one of these in cliff- and hill-climbing rack railroads, but they're also used in car steering systems, weighing scales, and many other kinds of machines as well. In a rack and pinion gear, a slowly spinning gear wheel (the pinion) meshes with a flat ridged bar (the rack). If the rack is fixed in place, the gear wheel is forced to move along it (as in a railroad). If the gear is fixed, the pinion shifts instead. That's what happens in car steering: you turn the steering wheel (connected to a pinion) and it makes a rack shift from side to side to swivel the car's front wheels to the left or the right. In simple weighing scales, when you load a weight on the pan at the top, it pushes a rack straight downward, causing a pinion to rotate. The pinion is attached to a pointer that rotates as well, showing the weight on the dial.

Sun and planet gears

If you need to convert reciprocating (back-and-forth) motion into rotation, you normally do it with a crankshaft and connecting rod; that's how pistons drive the wheels on steam engines. But you can do the same thing with gears. In this arrangement, a small gear called a planet (which, it's important to note, is fixed to a rod so that it cannot rotate) is moved around a second (usually bigger) gear called a Sun. As the rod moves the planet back and forth, the Sun spins around. Sun and planet gears were popularized by James Watt, who was unable to use a crankshaft in his pioneering steam engine because it was originally protected by a patent. (There's a great little animation of a sun and planet gear on Wikimedia Commons. Notice the black lines inked on the two gears showing clearly that the Sun rotates, while the planet does not.)

Bevel gears

If you want to change the direction of a machine's power through 90 degrees (or indeed any other angle), you can use angled gear wheels, called bevel gears. Typically they look like cut-off cones and the basic principle is always the same: power coming in from one direction is transformed so it goes out in another direction. You could achieve this with an ordinary pair of gear wheels, but a bevel gear has more teeth (and more area of each tooth) in contact at a time. This is smoother and quieter, reduces stress, and makes the gear better able to cope with varying loads. In this photo, which is a closeup of the gearbox in the very top photo, you can see different bevel gears hard at work.

What's the catch?

You might think gears are brilliantly helpful, but there's a catch. If a gear gives you more force, it must give you less speed at the same time. If it gives you more speed, it has to give you less force. That's why, when you're going up hill in a low gear, you have to pedal much faster to go the same distance. When you're going along the straight, gears give you more speed but they reduce the force you're producing with the pedals in the same proportion.

Artwork: Gears can give you more speed, but only by giving less force; they can give more force, but only by giving less speed. This is why a pair of gears can't create energy. With two perfect gears, you'd get exactly as much energy out as you put in; with real gears, friction, noise, air resistance and so on mean you get less energy out than you put in.

Whenever you gain something from a gear you must lose something else at the same time to make up for it. If that weren't the case, you could use gears to create energy and make what scientists call a perpetual motion machine-and that's absolutely forbidden by a law of physics called the conservation of energy. Formally stated, it says that you can't create or destroy energy, only convert it from one form into another. To put it more informally, as my old physics teacher used to say: "You don't get 'owt for nowt" or "There's no gain without pain"!

Where did you get those gears?

I regularly receive emails from teachers and students asking where I got the red plastic gears I've photographed in this article. They're from a wonderful construction set I had way back in the 1970s, made by a German company called Fischer Technik, which I still have today. It was like a kind of plastic version of Meccano without all the fiddly little screws and things, and there was equal emphasis on both static structures and dynamic machines. From their website, it seems Fischer Technik still make educational, STEM-related toys today, but I'm not sure whether you can get the full range of gears I had in my set. If you happen to know the answer, please do let me know!

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Gears - How do they work? - Different types explained and compared

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An easy-to-understand explanation of how gears work and why they can give a machine more speed or force (but not both at the same time).

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Part 1

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Bill Nye describes how hybrid engines work. Courtesy of Allison Transmission. This is the first of two parts; the entire program is 18 minutes long.

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Anna Carlsson The Six Simple Machines Wheel and Axle Lever Makes lifting weight easier by using a fulcrum to
redirect force over a longer distance and it is used to help lift things. Three ancient civilizations that used a lever was Egypt who used it to help make pyramids, Roman's used it for engineering, and Mesopotamian's used it for crops. Wedge A piece of wood, metal, or some other material having one thick end and tapering to a thin edge, that is driven between two objects and it helps keep things open.
Anceint Roman's used the wedge to help build the Roman temple, Egyptians used it to help build the pyramids, and Greeks swords were considered as wedges. Inclined Plane Makes it easier to move objects upward,
but you have to go further horizontally and it helps move things up or down. The Egyptian's used the incline plane to help build pyramids, they were also used in England for canals, and they were used to build the Roman temple. Screw Turns things into lengthwise movement and holds things together. In the east such as places known today as Greece and Isreal used it for oil presses, surgeons in Rome used them as drills, and Babylon used the screw as a water pump. Consists of a wheel with a smaller wheel in the middle of the wheel. The Wheel and axle help make moving things easier and three civilizations that used it are Northwestern India for moving crops, Roman Empire used it as a type of car, and the Indus Valley also used it to move things like crops. Pulley A pulley is a wheel with a grooved rim around which a cord passes. It acts to change the direction of a force applied to the cord and it is used to pull things up or down easier. Three civilizations that used the pulley were Roman Empire who used it for engineering, Egyptians used it to help make pyramids, and Mesopotamia's would use it to hoist items from animals. Resources http://www.google.com/search?q=ancient%20civilizations%20that%20used%20a%20lever&rls=com.microsoft:en-us&oe=UTF-8&startIndex=&startPage=1&safe=active&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=oNq8UKuyK4bc9ASt84HADQ&biw=1173&bih=633&sei=odu8UMj2Con89QSv-4CQDg#um=1&hl=en&safe=active&tbo=d&rls=com.microsoft:en-us&tbm=isch&sa=1&q=pulley&oq=pulley&gs_l=img.3...79172.80156.0.80312.6.3.0.0.0.0.188.297.0j2.2.0...0.0...1c.1.cm2lz68xpbk&bav=on.2,or.r_gc.r_pw.r_qf.&fp=641946b7a9ef900f&bpcl=39314241&biw=1280&bih=599 http://www.historylearningsite.co.uk/roman_engineering.htm http://www.champaignschools.org/staffwebsites/cainza/mesopotamianachievementsandinventions.pdf http://www.ehow.com/info_8078752_earliest-recorded-use-simple-machines.html http://wiki.answers.com/Q/What_ancient_civilizations_used_technology http://www.ehow.com/facts_5914374_uses-screws-ancient-civilizations.html

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Anna Carlsson The Six Simple Machines Wheel and Axle Lever Makes lifting weight easier by using a fulcrum toredirect force over a longer distance and it is used to help lift things. Three ancient civilizations that used a lever was Egypt who used it to help make pyramids, Roman's used it for engineering, and Mesopotamian's used it for crops.

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A Greek Analog Computer?

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Gadgets of Gears Gone By: Ancient Greek Analog Computer | Gadgets, Science & Technology

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Many people believe that ancient civilizations had much more advanced technology than we give them credit for. After all, the pyramids and other ancient ...

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It is believed that the pulley system was used as far back as 1500 BC by the people of Mesopotamia to draw water.

A pulley consists of a grooved wheel with a rope. As the name suggests, pulleys are used to pull and lift heavy loads. These are simple machines that make our life very easy, and unknowingly, we use them so many times on most days. Observe around, and you'll see a lot of examples of pulleys. It uses simple science to lift things. That way, you not only save your efforts of lifting heavy loads, but also makes the locomotion of things easier.

There are three types of pulleys: fixed pulleys, moving pulleys, and compound pulleys. Compound pulleys are a mixture of both, fixed and moving pulleys. In everyday life, there are so many examples of these simple, yet useful machines.

Here are some examples of this system that we use and see all around us.

A simple technique of pulley is used in case of blinds, and they help in pulling the curtains up and down. Similarly, in a theater system, pulleys are used to lift the curtains up.

A simple pulley system holding a flower basket, that can be lowered to water the flowers.

A pulley is used to drop the bucket into the well, collect water, and pull it up again. Though its use has become very less in modern times, we might perhaps find them in the country side.

Other Examples
► Adjustable clothesline
► Hanging chandelier, which can be lowered
► In the kitchen: dumbwaiter, hanging lights
► Simple motor pulley used in a sewing machine
► Sliding doors of bathrooms

Industrial and Other Activities

This is one of the most commonly observed pulley. It is used to lift heavy things, machines, collect debris, etc.

A sailing boat requires the help of pulleys to move the sails around as desired.

Pulleys provide locomotion to workers to move up and down to wash buildings from the outside.

Sports/Recreational/Other Activities

Many sports equipment use the pulley system for muscular exercises.

With the help of the pulley system, rock climbers can climb steep rock surfaces easily.

The wheel enhances the fishing rod in catching fish.

To hoist a flag up, the help of a pulley is required.

Other than the invention of the wheel, which embarked the progress of humans in the field of science, we have a lot to thank the pulleys too, for it is because of them that we could construct and expand tall skyscrapers, bridges, and also climb great heights (and descend too!). Of course, the above list of examples of pulleys is not exhaustive, and if you wish to add to it, feel free to use the comments section below.

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List of Examples of Pulleys in Our Daily Life

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Pulleys are simple machines that make daily life so easy. From pulling curtains up to lifting heavy machinery, pulleys are vital in many equipment and utilities. This article enlists such examples, along with pictures, that we come across in our everyday lives.

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From construction to freight to salvaging forsaken ships at sea, current and early cranes are simply the arms that do the heavy lifting powering our global industries. The world just wouldn't be the same without them-and it's our goal to make sure your cranes will perform powerfully, flexibly, and effectively until the jobs are done.

So how did cranes become such an integral part of all of our lives (whether we realize it or not)? Let's take a look back through history:
Democracy and Devotion: Greeks Invent the Crane
Necessity is the mother of all innovation-and you won't find a more urgent group of inventors than those under threat of being smote from above. For whatever reasons, the Ancient Greeks felt compelled to build huge temples to their gods, and traditional methods like ramps for moving and lifting the enormous building stones of massive monuments like the Parthenon just weren't going to get the jobs done. Meet the crane: at first a simple winch and pulley system, and later a compound pulley system credited to Aristotle.

Today, you can see the difference in the way temples were built in different time periods. Pre-cranes, building blocks actually tended to be much larger, because so much effort was required to push each one up a ramp that it was less labor-intensive to use bigger and fewer blocks. Post-cranes, blocks were smaller, but stacked higher, in more complicated and advanced structures, and more quickly.

In the end, the Greeks proved just how much more ambitious projects could be with the help of a crane. The Egyptian slaves responsible for building the pyramids block by ramp-elevated block are still squirming with envy in their graves.
Mobility and Versatility: Cranes Power the Roman Empire
Rome wasn't built in a day, but without the introduction of and improvement upon the Greek cranes, construction would've taken much, much longer than it did. In fact, the Romans were the first to use multiple cranes for cooperative lifting tasks, as is evident by the massive cornerstone blocks used in some of the famous structures.

But beyond the beautiful, historic, crane-built city still very visible today, perhaps the most impressive aspect of Roman crane use was the way they were used far from their home. Again-necessity drives innovation. And as the Roman Empire stretched further and further away from Rome, and as conquering armies became more and more ambitious, mobility and versatility in their cranes became key. The Roman army needed cranes that could move quickly, be assembled and torn down quickly, and perform a variety of tasks-all without losing their powerful lifting capabilities.

Today, you can see that influence in how mobile cranes are used all over the world. You find them on boats, docks, trains, and trucks, often able to be quickly adapted for difficult, unusual tasks. Lifting capacity has skyrocketed, up to 1,000 tons. In the end, the Romans proved just how much mobility and versatility multiply capability.

At K&L Clutch, we understand just how many ways your business relies on your lifting capabilities. When a crane breaks down, we can be there-just about anywhere in the world-with the industrial machine parts to get your project back on track in no time.

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Early Cranes | How Cranes Helped Build Civilization | Industrial Tools

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From construction to freight to salvaging forsaken ships at sea, current and early cranes are simply the arms that do the heavy lifting powering our global industries. The world just wouldn't be the same without them-and it's our goal to make sure your cranes will perform powerfully, flexibly, and effectively until the jobs are done.

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Ideas for the Classroom

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(Related to Pulleys & Gears)

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What is a Pulley? - Simple Machines | Science for Kids | Educational Videos by Mocomi