Gears The Transmitters of Mechanical Power Essay Example for Free

Gears The Transmitters of Mechanical Power Essay A body under net force is under tranlational motion and a body under net torque is under rotational motion; but they both have something in common and that is both have kinetic energy. This energy can be exploited to do some useful work. The mechanical energy of an object can be used to move another object. Some examples can be a rotating shaft of a motor, which can be used to move a vehicle for public transport. But for this to happen the force, the torque, the mehanical energy or the mechanical power needs to be transmitted from one moving or rotating body to another body. How mechanical force or torque or energy or power is transmitted from one body to another body? There are many ways, many mechanisms like pulley, chain, gears etc. So what is a Gear? Gear is a device, a mechanism through which mechanical force, torque, energy or power is transmitted from one object to another. To draw an analogy gear has same role for mechanical energy that electrical wire has for electrical energy. No not just that role of gear is much more than that. Gears act to increase or decrease the velocity from one moving element to another moving element. This way they has analogy with transformers in electrical domain. A gear is a circular object with a large number of teeth on it and two gears physically engage with each other to transmit mechanical power. This is illustrated in the following picture (http://www. osha. gov/SLTC/etools/machineguarding/animations/gears. html). Figure 1: Two gears engaged with each other In the subsequent sections we will briefly talk about different terminology about gears and about different types of gears: In the most coomon configuration a gear is engaged with another gear. However, it can engage with any other device which has compatible teath. One interesting arrangement is a linear object with teath, which is also termed as Rack. If a gear is engaged with a rack then forms what is known a Rack and a Pinion. It should however, be noted that a rack can be seen as a segment of a gear with infinite radius. Now let us talk about two gears of unequal size engages with each other as in figure 1, above. This combination produces â€Å"mechanical advantage† i. e. angular spee and torque of the second gear is different from that of the first gear. Let us explore this important concept about gears. Mchanical advantage The physical interlocking of the teeth in a pair of gears ensures that circumference of these gears move at the same linear speed. As the angualr speed is circumferential speed divided by its radius; the bigger gear moves at smaller angular speed than the smaller gear engaged with it. Let us look at it from the number of teath consideration. Because the teeth of two engaging gears are locked one to one, by the time all the teeth of the smaller gear have passed the point of contact only a fraction of the teath of the bigger gear has done that. In other words he smaller gear rotates faster than the bigger gear. This results in the following formula (Angular Speed A) x (Number of teeth A) = (Angular Speed B) x (Number of teeth B) or, (Angular Speed A)/ (Angular Speed B) = (Number of Teath B) / (Number of Teath B) This ratio is nothing but Gear Ratio. Similarly, one can dertermine torque ratio. The bigger gear experiences larger torque and vice versa. The torque ratio is equal to the ratio of the radii of the two gears and is inverse of the velocity ratio. Larger torque implies smaller velocity and vice versa. This fact is in confirmity with the law of conservation of energy. In this discussion we have ignored the friction, which dissipates the energy. Velocity ratio being a geometrical term remain unaffected by friction, however there is loss in torque ratio due to friction and thus actual torque ratio is always less than inverse of the velocity ratio. Because, gear is not perfectly circular due to presence of teath on the circumference, there is something called ‘pitch radius’, which is some sort of average between the radius at the root of the teath and at the outer of the teath and is used for these calculations for velocity ratio. Torque ratio etc. The pitch radius depends on the point of contact of the two gears. Also this point of contact keeps changing over time. Due to this the velocity ratio and torque ratio is not constant and instead keeps changing over the period of engagement. These ratios (velocity and torque ratios) that we have discussed so far are gross values and changes from point to point on the gear teath. However, the shape of the tooth can be made such that the velocity ratio remains constant with time on short and long term basis. This is done in good quality gears, because fluctuations in the velocity ratio causes undue vibration, put extra stress on the teeth, which can in turn break as the laod and the speed are many times very high. Keeping the velocity ratio constant is also desired from the precision considerations in devices like delicate instruments, eatches, clocks etc. Now let us compare gears with other mechanisms of mechanical power transmission. Gears and other Means of Power Transmission: There are other mechanisms for mechanical power transmission such as chains, belts, pulleys etc. Each of these has its own advantages and limitations. However, none is as diverse as gears. The problem of slippage is often encountered with these devices and the gears have edge over othe mechanisms. Similarly gears have constant velocity ratio, which is not the case with other devices. However, gears are generally more costly, but this higher cost is initial investment only and is paid back many more times due to very high life of gears than other devices. In the subsequent sections we will talk about different types of gears. Spur gear These are the most simple common gear. This is nothing but a disk with teath projecting radially and the leading edges of the teeth are aligned parallel to the axis of rotation. These gears are used for power transmission between parallel shafts. Such a gear is shown in figur 1, above. Helical gear This is a refinement over spur gear. In this gear the leading edge of the teeth is set at an agle to the axis of rotation and not not parallel to the axis of rotation as in case of spur gear. Because the gear is curved, this makes the tooth to be a segment of a helix. Such a tooth engages more gradually than do spur gear teeth. Therefore, this gear runs smoothly and produces much lesser noise than the spur gear. Besides, helical gear can tranmit power between non-parallel shafts as well. A pair of helical gears can be engage in two ways the shafts can be oriented at at either the sum or the difference of the helix angles of the gears. These configurations of the shafts are known as parallel or crossed, respectively. The parallel configuration is the mechanically more sound than the crossed configuration. In this configuration, the helices of a pair of engaging teeth meet at a common tangent, and therefore, the contact between the tooth surfaces will, is a curve, which extends some distance across their face widths. On the other hand, the helices do not meet tangentially in the crossed configuration, and between tooth surfaces only point contact is achieved. Because of this (the small area of contact), crossed helical gears are and can be used with light loads only. Generally, helical gears come in pairs. The helix angle of one is the negative of the helix angle of the other in this pair and this pair is termed as having a right handed helix and a left handed helix of equal angles. When engaged in the parallel mode, these equal and opposite angles add to zero i. e. the angle between shafts is zero or the the shafts are parallel. When engaged in the crossed configuration, the angle between shafts is twice the helix angle of individual gears. However, it should be borne in mind that parallel configuration of gears and paralles shafts are two different things i. e. parallel configuration of axes may not always lead to parallel shafts. The helical gear is shown in figure 2, below (http://en. wikipedia. org/wiki/Image:Helical_Gears. jpg). Figure 2: Helical gears in parallel and crossed configurations Double Helical Gear This gear is known as herringbone gear as well. This was invented to overcome the problem of axial thrust caused by helical gear. Here teath are of V shape. In this, each gear can be visualized as two standard and mirror image, helical gears stacked. This configuration cancels out the thrust because each half of the gear thrusts in the opposite direction. These can be interchanged with spur gears without changing the bearings.

What tree did you fall from? :: essays research papers

> >What tree did you fall from? Find your birthday, find your tree and then > >scroll down... This is really cool and somewhat accurate, also in line > with > >Celtic astrology. > >Jan 01 to Jan 11 - Fir Tree > >Jan 12 to Jan 24 - Elm Tree > >Jan 25 to Feb 03 - Cypress Tree > >Feb 04 to Feb 08 - Poplar Tree > >Feb 09 to Feb 18 - Cedar Tree > >Feb 19 to Feb 28 - Pine Tree > >Mar 01 to Mar 10 - Weeping Willow Tree > >Mar 11 to Mar 20 - Lime Tree > >Mar 21 - Oak Tree > >Mar 22 to Mar 31 - Hazelnut Tree > >Apr 01 to Apr 10 - Rowan Tree > >Apr 11 to Apr 20 - Maple Tree > >Apr 21 to Apr 30 - Walnut Tree > >May 01 to May 14 - Poplar Tree > >May 15 to May 24 - Chestnut Tree > >May 25 to Jun 03 - Ash Tree > >Jun 04 to Jun 13 - Hornbeam Tree > >Jun 14 to Jun 23 - Fig Tree > >Jun 24 - Birch Tree > >Jun 25 to Jul 04 - Apple Tree > >Jul 05 to Jul 14 - Fir Tree > >Jul 15 to Jul 25 - Elm Tree > >Jul 26 to Aug 04 - Cypress Tree > >Aug 05 to Aug 13 - Poplar Tree > >Aug 14 to Aug 23 - Cedar Tree > >Aug 24 to Sep 02 - Pine Tree > >Sep 03 to Sep 12 - Weeping Willow Tree > >Sep 13 to Sep 22 - Lime Tree > >Sep 23 - Olive Tree > >Sep 24 to Oct 03 - Hazelnut Tree > >Oct 04 to Oct 13 - Rowan Tree > >Oct 14 to Oct 23 - Maple Tree > >Oct 24 to Nov 11 - Walnut Tree > >Nov 12 to Nov 21 - Chestnut Tree > >Nov 22 to Dec 01 - Ash Tree > >Dec 02 to Dec 11 - Hornbeam Tree > >Dec 12 to Dec 21 - Fig Tree > >Dec 22 - Beech Tree > >Dec 23 to Dec 31 - Apple Tree > >APPLE TREE (Love) - of slight build, lots of charm, appeal, and > attraction, > >pleasant aura, flirtatious, adventurous, sensitive, always in love, wants > to > >love and be loved, faithful and tender partner, very generous, scientific > >talents, lives for today, a carefree philosopher with imagination. > >ASH TREE (Ambition) - uncommonly attractive, vivacious, impulsive, > demanding, > >does not care for criticism, ambitious, intelligent, talented, likes to > play > >with fate, can be egotistic, very reliable and trustworthy, faithful and > >prudent lover, sometimes brains rule over the heart, but

Internal Building Security Proposal Essay

Internal Building Security Proposal Access Control is an important part of any business. Anytime a business is under construction it will be more vulnerable to threats and attacks. Construction will need more protection because of the ability to gain easier access to a building because of the open areas within the building. Certain areas in a building are a target for attacks. Some areas are higher risk because of the information or high-value assets within the building. Access Control is the best way to wing out some threats and minimize other threats. Each individual at an access point will have several types of protection such as gates, lighting, cameras, detectors, sensors and other devices that can check individuals thoroughly and make sure each one is authorized to be in the building. Keeping individuals out that have no authorization can lower threats and minimizes chances of damage occurring externally. Access control will work from the outside in to protect a business. Technology is continuing to get better and there are a lot more devices available that can enhance security and help assist the personnel when concerning responsibilities. Access control still needs the support of security personnel to make sure all the devices are functioning properly. Technology has to be maintained to run properly and do what it is designed to do. Access Control was created to keep unwanted individuals from entering a location and to prevent from any employees or personnel from leaving with any valuable information unnoticed. There are so many ways to access a building that any vulnerable areas may be threatened at some point. Access control helps to minimize the vulnerabilities and lower threats against a business. Construction on a building will leave certain areas vulnerable and will be more difficult to secure because of all the individuals coming from outside of the business to do a job. More people can mean more threats, this will need more protection. Some of the types of technology that are becoming popular for protection are wireless access points, cameras, sensors,  detectors, wands, and computers. Security personnel are using these devices to detect and deter crime in the work environment (University of Phoenix, 2008). Wireless Access points and surveillance are becoming more common because of the portability. It is more difficult to carry around a big computer for monitoring purposes and access control. A wireless computer is much more compact and lighter to carry around while handling the responsibilities of monitoring employees at an access point. A building will also have a way for security personnel to monitor different areas of the building by using cameras. A wireless computer can make it easier to monitor these different areas all in one area. Cameras will not take the place of security but can make it easier for security to cover more ground successfully and still be able to perform other duties. One advantage that cameras have is that as long as maintenance is kept up that cameras will run non-stop even when security is unavailable or just in a different location. Crime can still occur with security on patrol. Areas more vulnerable can use cameras to help catch any activity that seems out of place. In most instances cameras are only viewed when something has already occurred and can validate an individual’s where physical where about during a certain time period. Sensors are a growing trend at access points. Many industrial buildings will have products that employees will have contact with during a work day. A business will use sensors on products to keep track of the location, while in the building. One product may be received and shipped from one location to the next until the process is complete and ready to be shipped to another building. Sensors can also be caught at access points if individuals attempt to leave the building with a product without authorization. One device that can find such sensors is the detector. At several access points for employees’ detectors will be present and scanned over an individual to ensure that no sensors are found before leaving a building during lunch and after work hours. A wand is just one type of detector that will scan and have an alarm go off when it detects certain materials. Individuals will have to physically take anything out of their pockets and show that it is not a business product. Another type of detector is a full body detector that can detect different objects on a person without having to do a strip search. Computers is somet hing that is storing more data for a business and also it has the capability of doing other tasks  such as viewing camera feed during recording, and keeping track of authorization, cards, and keys for employees. At different access gates, a card will need scanning before entering. A computer can make sure that the card scanned at the gate is valid. A private intranet will hold information for a business about employees, customers, employers, and the business products and services. This type of device will have access points within the system. A computer will have a private server but is still running on the internet and can be hacked. Hackers will try and find ways to access the information and retrieve or damage it. A business can find ways to strengthen the access points into the private database and prevent hackers from accessing business information. A computer will have software, updates, passwords, and programs to protect intruders from hacking thedatabase without authorization. Computers need protection to prevent from damage. A system that has been hacked can corrupt the system and make it unusable. A way of protecting a system before it is damaged is having a back-up system. If the system is destroyed the back-up can make a business more prepared for any threats or damage to restore the system back to normal (University of Phoenix, 2011). A business will have certain areas that contain more vital information or equipment that can be threatened by construction. Areas that are more high-value need more layers of protection against any threats. Data of a business will contain information such as customer records which will have information, such as where they live, telephone numbers, full names, social security numbers and more which can be used to commit other crimes such as fraud. High-value areas are more vulnerable because the amount of damage that can be done will cost more than in other areas of the building. For instance, bathrooms of a facility will have little to no products and are less of a risk than an office. So the security will focus more on offices because of the amount of value. Some areas may only include security cameras for monitoring an area. A big high-value area could include the main power room. This area can cause damage to not only the building but also to the equipment. The main power room may have heavier walls, more cameras, passwords, security personnel, and other types of protection. There are several considerations that should be kept in mind such as who can access the room, who will be working in a room that is in the high-value areas? High-value rooms will be threatened  normally both internally and externally. If a construction area is near anything high-value at a business, extra precautions may be taken to make sure the area is secure from both types of threats. Internal building security is important to have for every business to protect the business. A business has many assets that are unable to protect themselves. Security personnel are hired to protect the business, the people, and the environment. In a new building security will be less effective because of financial status and experience with threats. The type of threats will vary and the only way to avoid vulnerabilities is attempting to use other existing buildings methods when concerning access control, surveillance, and the protection of high-value areas. A business has to prepare for threats before they occur and then deal with new ones as they arise if there is no prior experience with the type of threat. For example, hackers are always finding ways to hack a system. No code or encryption that is created is identical and all the programs and software in the world can protect a business from all threats. A business needs constant management to evolve with society and the new changes. Taking advantage of new technologies will improve the chance of success for both the business and security. References University of Phoenix. (2008). Design and Evaluation of Physical Protection and Systems.

Charles John Huffam Dickens Great Expectations - 2301 Words

Charles John Huffam Dickens was born on February 7, 1812 in Portsmouth, England to Elizabeth and John Dickens. He came from a large middle class family that suffered from debt and received schooling from Wellington House Academy. After completing his education he pursued a career as a freelance reporter for Parliament and a clerk at a law firm. His career as a reporter provided a gateway to his embarkment as a full time novelist who produced complex works at an incredible rate. His career took off after he wrote Sketches by Boz in 1836 quickly followed by The Pickwick Papers. He wrote Great Expectations in 1861 towards the end of both his life and career, in which he had experienced a bout of cynicism because of the occurrences in London, England at the time and personal problems with faithfulness and trust. On June 9, 1870, Dickens had a stroke and, at age 58, died at Gad s Hill Place, his country home in Kent. Dickens would later be known as one of the greatest and most influential writers of the Victorian Period. In the coming of age story Great Expectations, the Victorian novelist, Charles Dickens defies preconceived ideas about the importance of social status and gender roles in society through a realistic depiction of Victorian life in England utilizing his struggles and experiences with poverty. â€Å"Charles Dickens,Early Victorian Novelists: Essays in Revaluation† by David Cecil comments on how Dickens poetry is not great and that his use of humor is one of hisShow MoreRelatedCharles Dickens Great Expectations943 Words   |  4 Pages This is true in many cases but none as much as in Great Expectations. In many ways the narrator/protagonist Pip is Charles Dickens in body and mind. While there are many differences between the story and Charles Dickens life there remains one constant. 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Over the course of his life he wrote some of the most famous and beloved stories, from â€Å"A Christmas Carol,† â€Å"Great Expectation†, and â€Å"Oliver Twist†, to â€Å"Nicholas Nickleby† and â€Å"Davis Copperfield.† Today Dickens is considered to be by many, one of the most well-knownRead MoreThe Victorian Er A Important Part Of Our History1688 Words   |  7 PagesThe Victorian Era was a very important part of our history. That is why I want to familiarize you with it before we get directly to Mr. Dickens. This was a period in time when the times were changin g in a vast number of ways. The Victorian era was a time of peace, refined sensibilities and prosperity for Britain. This era was the first where music, dramas and opera were performed openly and were attended by mass amounts of people. Also to become in the Victorian era were â€Å"dining clubs† where gentlemenRead MoreEffective Images of People and Places Created by Dickens1384 Words   |  6 PagesCreated by Dickens Charles John Huffam Dickens was born on February 7, 1812 in Portsmouth. Dickens childhood was not particularly happy one, and many of the events he endured and people he met inspired his books. The second child of a clerk in the navy pay-office, Dickens moved to London with his family when he was two years old. His father was often in debt, and finally in 1824 was sent to debtors prison with the rest of the family in Marshalsea. Dickens, on the otherRead MoreThe Evidence Of Unbound Loyalty1746 Words   |  7 PagesOliver, ill-treated and hungry, approaches his masters saying â€Å"Please, sir, I want some more† (Dickens 11), Charles Dickens enthralls his readers in the harsh, twisted journey of Oliver Twist. Through a series of exciting events full of abuse, loyalty, hatred, and love, Dickens portrays the overlooked difficulties of the poor, lower class that Oliver Twist’s action-packed life has been subject to. Some of Dickens most loved characters, including the adolescent pickpocket under the pseudonym the Artful