3. ROTARY TRANSMISSION

Rotary transmissions systems put two rotating elements into contact. These mechanisms have two purposes.

• Transferring rotary force from an input location to another location.
• Changing the rotary speed by using rotating elements of different sizes.

All the mechanisms keep the same ratios, but each one offers a different advantage.

Uses: Friction wheels and pulleys are often used in toys and other devices with moving parts, such as industrial rollers or conveyor belt systems. Gears are used in cloks, while sprockets and chains are commmon in home appliances.

3.1 Changes in speed

If we want to increase the speed of a rotary systems, we must transmit motion from a large element to a smaller (output) element. However, when we increase the speed we also decrease the rotary force, or torque.

The opposite is true if we want to decrease the speed of a rotary systems. we must transmit motion from from a smaller (input) element to alarger (output) element. At the same time, we also increase the torque. If the input and and output elements are the same size, the rotary speed remais constant. The rotary force will also remain constant.

Pulley : Increase speed systems  D1>D2    N2>N1

Pulley 2: Constant speed systems D1=D2    N2=N1

Pulley 3: Decreasing speed systems D1<D2   N2<N1

3.2 Speed ratios

The relationship between the speeds of the two wheels is inversely proportional to their sizes.

N2/N1 = D1/D2

If we want to calculate the size ratio of wheels or pulleys, we can compare their diametre, radius, or circunfrence. 

3.3. Belt drives and gear trains

A belt drive is a sysstem of pulleys connected by belts. each belt connects a pair of pulleys, so they turn together.

to understand how a belt drive works, we can analyse the example adove:

• wheel 1 turns wheel 2, which moves faster because it is smaller. The size ratio between the wheels is D1/ D2 = 1.5.If wheel 1 makes 1 rotation, wheel 2 makes 1.5 rotations.

• Wheel 2 and wheel 3 are connected to the same axis, so they turn together. If wheel 2 makes 1.5  rotations, wheel 3 also makes 1.5 rotations.

• Whell 3 turns wheel 4, which moves faster because it is maller. The size ratio between the wheels is D3 / D4 = ". if wheel 3 1.5 rotations, wheel 4 makes 1.5x2=3 rotations

To calculate the ratio of transmission, between the  first wheel and the last wheel of a belt drive, we must multiply the ratios of transmission of the the first pair of wheels and the second pair of wheels:

                                                                N4/N1 = D1xD3 / D2/D4

N is the speed of rotation and D is the diameter of the wheel.

3.5. Worm drive

A worm drive reduces the speed of rotary system very effectively. A worm drive has two parts: a worm shalt and a worm gear. The shaft has two, three or even more grooves. Each groove interlocks whit one tooth of the worm gear.

Uses: we use worm drives for tuning of a guitar, for elevator mechanisms and for speed reducing systems.

4. TRANSFORMATION OF MOTION

Some mechanisms transform linear motion into rotary motion. Most of these mechanisms are reversible. they also transform rotary motion into linear motion.

The linear motion can be unidirectional or reciprocating. Reciprocating motions alternate from one side to the other.

4.1 Rotary-linear transformation

Wheel

Wheels are essencial parts of bicycles. They let us move more easily because they reduce our contact with the ground and  decrease friction. However, if there isn't enough friction, the wheels can slide out of control.

We need less force to move vehicles with larger wheels and they more more quickly.

Rack and pinion mechanism

A rack and pinion mechanism has two parts. The Rack is a bar with many teeth and the pinion is a gear with teeth that interlock with the rack. When the pinion rotates, the rack moves in a linear direction. If the mechanism is reversible, the pinion also rotates when the rack moves. 

Uses: We use rack and pinion mechanism for sliding doors, conveyor belts and other devices that require precise movements.

Nut andbolt mechanism

A nut and bolt mechanism transforms rotary motion into linear motion. It has two parts: a bolt or shaft whit a spiral groove and a nut that turns around it. We can turn and tighten the nut in the order to hold things together.

Uses: We use nut and bolt mechanisms to hold things together. We also find them  in scissor jacks for lifting cars, water tap mechanisms and screw-top bottles.

Which and crank mechanism

A winch is a cylinder that rotates around a horizontal axis. We attach a rope to the winch and to a load. Then we turn the crank to rotate the winch. The rope rolls up around the winch and lifts the load. The crank increases the force and the winch transforms rotary motion into linear motion.

The increase in force is proportional to the ratio betweeen the radius of the crank and the radius of the winch . These ratios obey the law of the lever.

                                                           Fxd = Rx r

Uses: we use winches for lifting loads. We find them in construction cranes and in the mechanism that raises window blinds in our homes.

4.2. Reciprocating rotary-linear transformation

The pedal mechanism of a bicycle transform the reciprocating movements of our legs into continuous rotary motion. In a similar way, the pistons of a car engine produce a reciprocating linear motion that turns the wheels.

Crank and rod mechanism

In the picture, you can see the parts of a crank and rod mechanism. The piston moves a rod forwards and backwards. this rod turns the firs wheel. The second wheel turns because it is connected to the first wheel by another rod.

uses: This mechanism was  important for the first steam engines. Today we find cranks and rods in internal combution engines, as well as windscreen wiper mechanisms.

Crankshaft mechanism

We can connect multiple rods to one shaft. The rods are connected to cracks, and the cranks are connected to the crankshaft.

In the case of a bicycle, our legs act like connecting rods that turn the crank mechanism of the pedals.

Uses: we use crankshafts for combustion motor that use pistons. we also use them for sewing machines.

Cam mechanism

A cam is an irregulary shaped device that rotates on a shaft. When the cams rotates, it pushes a special bar called a follower. The follower can move other parts or it can turn a switch on and off.

A clockwork music box also has a camshaft mechanism.

There is a metal roller with many tiny bumps. When the roller turns, the bumps act like cams, moving a series of metal teeth that play musical notes.

uses: We can find camshafts in toys, automatic tools and combustion motors.

Some cams are circular, but with an axis of rotation that is off-centre. These are called eccentric cams because they rotate in an irregular or eccentric way.

Uses: There are often eccentric cams in sewing machines and other devices that transform rotary motion to linear motion.

5. MECHANISM THAT CONTROL MOTION

5.1 Direction control: ratchests

A ratches is a mechanism that controls the direction of motion. It allows motion in one direction, but not in the olther, as you can see in the picture.

Uses: We find ratches in watches, cable-tensor and elevator brake systems.

5.2. Speed reduction: brakes

brakes: Use friction to reduce speed. They are activated by certain levers. The lever transmits force to an output receptor, which puts pressure on the wheel. This produces friction, which slows down the wheel.

There are various types of brake systems according to where the friction is produce:

Disc brakes: A disc is connected to an axle. Brake pads apply pressure to the disc.

Band brakes: A drum is connected to an axle. A flexible band applies pressure to the outside of the drum. These brakes were used in carriages and they depended on the strength of the driver.

Drum brakes: A drum is connected to the axle. A pair of brake shoes apply pressure to the inside of the drum.

2.Linear transmission of motion

2.1 Levers

A lever is a rigid bar that turns around a point called a fulcrum.
Each force produces a specific torque, which is the force multiplied by its distance from the fulcrum.

                               TORQUE=FORCE x DISTANCE

When the forces acting on opposite ends of a lever are equal, we say the lever is in equilibrium. We can express this mathematically as the Law of the lever.
                   
                                         F x d=R x r

Classes of levers:

We can levers into classes according to the locations of the fulcrum, force, and resistance.

                                            

2.2 Pulleys and compound pulley systems.

In the systems of pulleys, the equilibrium between the forces depends on the path that the the rope  follows.

Pulleys:

 A pulley is a wheel that rotates around an axis and has a groove. If we pull ropes belts or chains through pulleys.

Compound pulley systems

A compound pulley system is a combination of fixed and movable pulleyss. It is also called a block and tackle system. 

Horizontal system

Exponential system

Vertical system

Mechanisms

1. What is a mechanism?

Everyday mechanisms that make life easier and more enjoyable.

• The clain of a bicycle transfers motion to the back wheel.

• The bar of a seesaw forms a lever that we can use for fun

• The gears inside old-fashioned clocks let us measured time

• The pulley system above a well helps us to bring up water

The mechanisms all have something in common. They make work easier because they transmit and transform force and motion.

The mechanisms requiered the input force.

The mechanisms transmit motion and force to receptors that finally perform the work.

This is the output force and motion.

1.1 The parts of a mechanism 

Mechanism transmit and transform force and motion from an input source to an output receptor. This transmission and transformation lets us perform different types of work with more comfort and less effort.

The Web

1. Web 1.0,  2.0,  3.0 

Web 1.0 or the read-only: In the 1990s, the information on the Internet was only for reading. People could not interact with other people or with the content. The information online was not updated very frequently.

Web 2.0 or the social network:  This was developed during the first decade of the 21st. century. This web is bidirectional. User could receive information, but also created and share information. For example email, chats, videoconferences, forums, blogs, wikis. Social networking was born.

Web 3.0 or the semantic web:  From 2006 onwards, new technologies could understand and work with the information that they received. Tecnology evolution: artificial intelligence (AI); Applications that do not use a browser, such as smarthphone apps; virtual reality; and Global Positioning System (GPS)

In this web we can tools which help us Personal Learning Enviroment: *Finding information, *Managing information, *Sharing information, *Creating information.

2.Finding information

The most common sources of online information are web pages and news feeds (RRS).

2.1 Web pages: Is a collection of documents that can include text, audio, images, video and hipertext links to other web pages. A browser is a programe that locates others pages web by its address.

The success of a web page often depends on the level of interactivity that it offers. As a youtube, Dailymotion.

A search engine is a web page with a database of information about other web pages and their content.

We should also analyse the information to decide if it is true or complete.

2.2 News feeds: Rich site summary (RSS): Rich Site Summary (RRS) is a subscription service that provides users with frequent updates from media websites, blogs and others web pages.

RRS news feeds are convenient and time-saving. Since subbscribes receive the information  automatically. You can Subscribe in two way:

* Direct from the web page, by clicking on a `subscribe´ icon.

* Through a news aggregator program (online or downloadable), can be to smartphones with Android or IOS operating systems.

3. Managing information 

3.1 Social bookmarking Is an Internet tool that lets us organise, use and share information more efficiently (similar to the favourites). All of the contend is stored in the cloud so we can access it from any location in the world. Somo applications are:

Delicius Is a service that lets us sae our favourite web pages along with descrption and a list of key words (tags). we can share this information with the others people.

Diigo Defines itself as a multi-tool for knowledge management. Among other funtions, it lets us bookmark the pages that we visited and created a digital library in the cloud. we can access this library from any location and select the information we want to share.

Evernote Provides a convenient workspace where we can collect information by capturing articles and images from the internet. Then we can add notes and share information with other people. Evernote is convenient for making presentations, and is available for mobile devices.

3.2 Working in the cloud: Some Internet services let us created, save and modify documents online. This is called 'cloud computing'. (Drive, Dropbox and OneDrive). The two main advantages of these services are:

* Acces to our files from any location or device with an Internet connection.

* The ability to share our files with other people.

In addition to storing and sharing information in the cloud, we can also use programs for word-processing, spreadsheets and presentations.

4. Sharing information 

A lot of people continue using classic online services (email, chats and videoconferences), social networks have revolutionised how we spread or share information. The social networks divided in two Vertical and horizontal social networks.

4.1 Horizontal social networks: The users of horizontal networks form communities who have diverse interests and a wide variety of reasons for using the app. The most popular are:

Facebook:This app allows groups of friends to publish both public and privated messages with text, news, links, photos, and videos. they may share infotmation about how they are feeling or what they are doing at any moment.

Twitter: This social networks has some unusual features. User publish short text messages (tweets) with no more than 140 characters, which called microblogging. On twitter, the relationships between user are not always bidirectional.

Google+: This social networks allows user to created circles of friends in order to share information.

They can share photos and form public or private communities. An instant message application called Hangouts lets user connect with others for audio conversations and videoconferences.

4.2 Vertical social networks: This application can be personal or professional.

Sharing professional information: Linkedin is the most popular network for all kinds of professionals.

Sharing general information: With friendfeed, people can created private groups to share information about projects, organise events and exchange photos or experiences with their friends.

Sharing photos: Instagram, Pinterest, Picassa are popular.

Sharing videos: Youtube, Dailymotion and Vimeo are common examples.

Live streaming: skype, twitch tv, Livestream and Upstream.tv are often used.

There are many others services related to sports, cinema, books and other topics.

5. Creating information:

On the Internet, we can quickly and easily create information about anything that we consider interesting. The most popular tools for creating and distributing information on the Internet are web pages, blogs and wikis.

5.1 Web pages: In previous sections, you have read about web pages as sources of information. The first steps is to plan the design and content of everything that will appear on your web pages. The content must be interesting to attact the maximum number of visits.

The steps that you must follow are:

1. Register a domain.

2. Sing up with a host server.

3. Desing and created your web page.

4. Upload your page to the server.

5. Update your pages regularly.

Domain names: To register a domain for your web page, your must choose a name that is not already being used.

Host servers: Companies such as Arsys Nominalia host web pages by offering space on their servers. Domain registration serves may also provide hosting, and web page desing companies often include both registration and hosting.

Designing and creating a web page: a website is a set of web pages under the same domain name.

Designing a web page.

There are no official rules fot how a web page must look. you need some basic knowledge of desing, to insert images or change colours.

Creating your web page

1. Direct programming is the most difficult option, since requires knowledge of programming languages and tools.

HTLM is user for static web pages desing. It was first language invented for web page creation, there is a new version XHTML

CSS is used to created the structure of a document.It's  presentation tool that holds the HTML content.

PHP is a language used to created dynamic web pages.

MySQL is a database management system used for dynamic web pages.

2. Using a Content Management System: we can use a CMS to create dynamic web pages. this process includes editing the structure of the page and managing the content.

These systems have several advantages.

a. They are fast because they don't require direct programming.

b. Some are free.

c. Some CMS services offer a package that includes hosting and CMS installation. sometime require a particular database format, such as MySQL.

There are also some disadvantages:

a. You cannot do anything you want. (limited funtions)

b. CMS programs are complex and it taakes a long time to learn how to use them.

c. you must have a server with enough storage space for the program.

The most popular CMS services are Joomla, Drupal and Wordpress. Also use Prestashop.

3. Using a web developed program: These programs translate your web page desing into HTLM language, you need to know how to program. Kompozer, Web Creator, Adobe Dreamweaver Professional.

4. Using the online hosting services that some pages offter: These web creation services are quite complete and the result are very proffesional. there are two version a free version or a must you pay.

a. They include advertising, which some people may find unattractive.

b. The web address may be rather long and difficult to remember.

Services like Wix, Jimdo, Hostinger, 1&1.

Uploading a web page to a server. If you are not using an online hosting service, you will need to upload your CMS program or your web page to the server.

You can use FTP programs to upload your web page to the server. Filezilla, CuteFTP.

These programs manage the transfer of web page files from your computer's hard drive to a server. we call this uploading.

5.2 Blogs: Weblogs or blogs are a special typeof web page. They were originally used as online diaries for people to share their personal experiences.

Blogs have other characteristics which made them interesting:

* The same blog can be shared by various bloggers working together as a team.

* Blogs can include hyperlinks to photos, audio recordings or videos.

* We can use blogs to make daily reports about a oroject and receive helpful feedback from other people.

* Businesses can use blogs to improve their customer service, by quickly responding to questions or complaints about their products. They can also post manuals, videos and up-to date information for their customers.

Blogger, WordPress, tumblr.

5.3 Wikis: Is a collection of web pages than visitors can edit, modify or expand. Like other web pages, wiki contend must be stored on a server. Normally, this would require paying for a hosting service, but many wikis use a free online service instead. Wikispace, PBWorks.

Adding new content to a wiki page is quite easy:

1. Look for an edit button and click on it.
2. Make changes to the existing contend or write a new contribution.
3. Look for a Save button and click on it to save the changes.

WIKIPEDIA: ( Created January 2001), Is a universal encyclopaedia with no restrictions on use, modification or redistribution Anyone can contribute their knoledged to the project.

My Presentation

I'm Daniel Mendez, I study at the Institute La Rabida. I'm third course of that and I'm fourteen years