Couplings Elements Essay

Couplings are mechanical elements that ‘couples’ two drive elements which enables motion to be transferred from one element to another. The drive elements are normally shafts. We tend to see lot of applications of the couplings mainly in the automobiles, for example the drive shaft which connects the engine and the rear axle in a bus or any automobile is connected by means of a universal joint. In order to transmit torque between two shafts that either tend to lie in the same line or slightly misaligned, a coupling is used. Based on the area of applications there are various types of coupling available. But they are generally categorised in the following varieties 1. Rigid Couplings 2. Flexible or Compensating Couplings 3. Clutches to are a type of Coupling – We will the dealing on them separately. RIGID COUPLINGS Rigid Couplings are mainly used in areas where the two shafts are coaxial to each other. There are many types of couplings that fall under the rigid couplings category. They are  · Rigid Sleeve or Muff Couplings- This is the basic type of coupling. This consists of a pipe whose bore is finished to the required tolerance based on the shaft size. Based on the usage of the coupling a keyway in made in the bore in order to transmit the torque by means of the key. Two threaded holes are provided in order to lock the coupling in position. The photo shows a type of the rigid sleeve or muff coupling.  · Flanged Coupling – The coupling basically consists of two flanged end pieces as shown in the figure. A spigot and recess is provided in the flanges to provide location between them. The flanges are connected firmly by means of fitted bolts which are tightened accordingly to the torque to be transmitted. FLEXIBLE OR COMPENSATING COUPLINGS Flexible couplings are normally used in areas where the coaxiallity between the connecting shafts is not always assured and in areas where there is a possibility of occurrence of shocks in the transmission is applicable. They are also called as Elastic Couplings. By construction these couplings tend to have a elastic member in between the two connecting entities. The different types of flexible couplings are 1. Flanged Pin Bush Couplings 2. Bibbly Coupling 3. Gear Tooth Coupling 4. Tyre couplings 5. Elastomeric Couplings – This consists of jaw type and S-flex couplings. 6. Oldhams Coupling 7. Universal Coupling or Hooke’s Coupling 8. Bellows Coupling Each of the above couplings are quite unique in their construction and we can deal in detail on their constructional and working aspects in separate articles. BIBBLY COUPLING: This article deals with Bibby Resilient type couplings. The article describes constructional aspects of the coupling and the selection procedures for the coupling. * Named after its Inventor Dr. James Bibby in 1917, this coupling is still one of the most sought after flexible couplings for heavy shock applications. Let us now look at the constructional features of the coupling. 1. The Coupling consists of two flanges or hubs specifically mounted on the drive and the driven shafts respectively. These hubs contain axial grooves cut on their circumference. 2. The two couplings are joined or held together by means of a specially designed grid spring. 3. The total assembly is enclosed in a casing or shell filled with grease for low speed applications or, in high speed application with high viscosity oil. Now let’s look at the working aspect of the coupling and how it tends to reduce vibration and prevents the build up of resonance in the system. a.) The specially designed spring is wound up through the grooves forming a series of resilient bridges throughout the periphery of the coupling. b.) The grooves are tapered up at the edges (see photo) in order to provide extra flexible spans to the spring at normal loads and tends to support the spring at the sides whenever overloading occurs. c.) The stiffness of the spring depends on its unsupported length of each of its flexible span. The unsupported length tends to vary with the loads producing a varying stiffness for the coupling based on the loading. d.) This action tends to produce a detuning action altering the torsional vibration frequency of the system that prevents the build-up of resonance. Some applications of Bibby Couplings are 1. Cement Mills – in grinding and crushing machinery. 2. Cranes 3. Conveyors 4. Turbines 5. Marine Auxiliaries 6. Paper Mills Bibby couplings can be used for applications with powers varying from as low as 1 h.p to about 100,000 h.p. per 100 rpm of the coupling. Correspondingly the couplings are available in varying sizes ranging from 100mm diameter to 4000mm diameter. Bibby couplings are capable of taking axial and radial misalignments to a very small extent only. It is necessary for the user to ensure that both axial and radial misalignments are kept to the minimum possible. Selection procedure for Bibby Couplings: The selection of the Bibby coupling is mainly based on the torque being transmitted by the coupling. Each coupling has a characteristic value for the torque transmitted by it to the revolutions per minute of the coupling. The rating of the coupling is given by Rating = Maximum power to be transmitted in h.p/ r.p.m of coupling In order to account for contingencies like shocks, sudden stops, stalling, etc. a factor of safety is to be considered during selection of the coupling. Rating of coupling to be Selected = Max. power of coupling* Factor/ r.p.m. of coupling The chart containing the factors to be considered is given below based on the application and driving machinery. See the selection chart below for the selection of corresponding coupling based on the power. Note: This chart is an indicative for the selection of the Bibby coupling. Kindly refer to an actual manufacturer’s catalog for selection as ratings may vary from manufacturer to manufacturer. GEAR COUPLING: This article deals with Gear Couplings. The article describes constructional aspects and selection procedures for flexible gear couplings. * Couplings are used as connecting elements between two shafts. The complexity in the type of connectivity, the power to be transmitted and the area of application tend to play a vital role in the selection of the type of the coupling. Gear Couplings belong to the category of flexible couplings that are capable of transmitting very high torques. Constructionally the gear coupling utilizes the advantages of gear engineering; practically the coupling is a complete gear assembly. Let us now look into the constructional aspects of the coupling. 1. The gear couplings consists of a forged sleeve with internal teeth cut on its inside. The forged sleeves are normally two halves possessing internal gears in both of them. In certain cases the forged sleeve tends to remain a single piece. 2. Two hubs with external teeth containing the same number of teeth as in the internal gear is present with each one being mounted on the driven and driver shaft respectively. The tooth profile of the external teeth is normally crowned in order to take up more loads. 3. The entire assembly in normally enclosed and is provided with gaskets at the joints and O-rings at vantage points in order to prevent the leakage of the lubricant filled inside the coupling, 4. Lubrication plugs are provided at vantage points in order to lubricate the couplings during predetermined intervals of time. Tooth forms in the Coupling: Three types of external teeth are used in gear couplings. The only difference is the manufacturing methodology of the same. a.) Straight Teeth: The external teeth in the hub are straight. During the condition of misalignment in the coupling the contact pattern between the internal gear and the external gear tends to be line type of contact as shown in the figure. b.) Crowning with constant radius: The external teeth are barrel shaped with a constant radius in order to increase the area of contact and move the area of contact to a near middle portion of the teeth. c.) Crowning with variable radius: The external teeth are barrel shaped with a variable radius instead of constant radius. This increases the area of the contact significantly compared to that of the constant radius crowning. The maximum degree of misalignment permissible in gear couplings is from 0.5 Degrees to 1.5 Degrees. This varies with the size of the coupling being used. Selection procedure for gear coupling: The gear couplings are selected based on the torque ratings. 1. 1. The torque transmitted by the coupling is to be determined. 2. 2. Based on the application the appropriate service factor needs to be determined. A reference chart on the service factors is shown below. 3. 3. The equivalent torque is to be determined by multiplying the service factor with the torque transmitted. 4. 4. Select the coupling based on the equivalent torque value calculated. A reference selection chart is given below for example. JAW TYPE ELASTOMERIC COUPLING: This article deals with Jaw type Elastomeric coupling. The article describes the constructional aspects of the coupling and selection procedures. * Couplings are indispensable mechanical power transmission elements used for connecting shafts. Flexible couplings in particular are used in areas where misalignment needs to be accommodated (the flexibility is highly restricted based on the type of Elastomeric material used) and also to take up shock loads at the driven end, thus protecting the driving element like a motor or such. Jaw Type Couplings tend to have a flexible member or Elastomeric member between the two metal components. The flexible member is also called the â€Å"Spider.† The Spider material can be made from different types of rubber or plastic possessing varying degrees of hardness in order to suit the load carrying capacity of the system torsional characteristics. The constructional features of the Jaw type coupling are shown below. The dimensional drawing as wel l as the nomenclature of the coupling is also enclosed. Here as some of the key aspects on the constructional features of the Jaw type coupling. These points are to be considered for the proper selection of a coupling. – The metal hub is constructed of sintered iron, cast iron, or aluminium or stainless steel. The type of metal hub is mainly based on the area of operation of the coupling and its inertia aspects. – The spider is normally made up of a nonmetallic element like rubber, urethane, hytrel because of their Elastomeric properties and in very rare cases bronze is used. BEAM COUPLING: A beam coupling A beam coupling, also known as helical coupling, is a flexible coupling for transmitting torque between two shafts while allowing for angular misalignment, parallel offset and even axial motion, of one shaft relative to the other. This design utilizes a single piece of material and becomes flexible by removal of material along a spiral path resulting in a curved flexible beam of helical shape. Since it is made from a single piece of material, the Beam Style coupling does not exhibit the backlash found in some multi-piece couplings. Another advantage of being an all machined coupling is the possibility to incorporate features into the final product while still keep the single piece integrity. Changes to the lead of the helical beam provide changes to misalignment capabilities as well as other performance characteristics such as torque capacity and torsional stiffness. It is even possible to have multiple starts within the same helix. The material used to manufacture the beam coupling also affects its performance and suitability for specific applications such as food, medical and aerospace. Materials are typically aluminum alloy and stainless steel, but they can also be made in acetal, maraging steel and titanium. The most common applications are attaching encoders to shafts and motion control for robotics. Oldham Animated Oldham coupler An Oldham coupling has three discs, one coupled to the input, one coupled to the output, and a middle disc that is joined to the first two by tongue and groove. The tongue and groove on one side is perpendicular to the tongue and groove on the other. The middle disc rotates around its center at the same speed as the input and output shafts. Its center traces a circular orbit, twice per rotation, around the midpoint between input and output shafts. Often springs are used to reduce backlash of the mechanism. An advantage to this type of coupling, as compared to two universal joints, is its compact size. The coupler is named for John Oldham who invented it in Ireland, in 1821, to solve a paddle placement problem in a paddle steamer design. * * it is recommended to use manufacturer’s alignment target values to set up the machine train to a defined non-zero alignment, due to the fact that later when the machine is at operation temperature the alignment condition is perfect Coupling maintenance and failure Coupling maintenance is generally a simple matter, requiring a regularly scheduled inspection of each coupling. It consists of: * Performing visual inspections, checking for signs of wear or fatigue, and cleaning couplings regularly. * Checking and changing lubricant regularly if the coupling is lubricated. This maintenance is required annually for most couplings and more frequently for couplings in adverse environments or in demanding operating conditions. * Documenting the maintenance performed on each coupling, along with the date.[2] Even with proper maintenance, however, couplings can fail. Underlying reasons for failure, other than maintenance, include: * Improper installation * Poor coupling selection * Operation beyond design capabilities.[2] The only way to improve coupling life is to understand what caused the failure and to correct it prior to installing a new coupling. Some external signs that indicate potential coupling failure include: * Abnormal noise, such as screeching, squealing or chattering * Excessive vibration or wobble * Failed seals indicated by lubricant leakage or contamination.[2] Checking the coupling balance Couplings are normally balanced at the factory prior to being shipped, but they occasionally go out of balance in operation. Balancing can be difficult and expensive, and is normally done only when operating tolerances are such that the effort and the expense are justified. The amount of coupling unbalance that can be tolerated by any system is dictated by the characteristics of the specific connected machines and can be determined by detailed analysis or experience.

Radio Broadcasting Essay Example | Topics and Well Written Essays - 1000 words

Radio Broadcasting - Essay Example After the American government stepped in to regulate this air traffic of signals by allotting licensed frequencies to the private operators, the era of commercial broadcasting came into being and led to a perceptual shift in the American culture. The men and boys saw the experimentation with radio as a symbol of masculine prerogative, brought it into their homes, and introduced it to the other family members. The listeners discovered the new face of their individual identities, closely linked to the idea of cohesive nationhood, through broadcasts of diverse entertainment programs and news items. Gradually, commercial reasons led to the introduction of advertisements interlaced with the main items, as well as standardization of broadcast timings, for most of the programs. With this it was possible for listeners to tune in to multiple broadcasts by adjusting their own schedules accordingly. The network programs allowed people to sit and listen to their favorite serials, like the women's serial drama nick named "soap opera", at the same time everyday or every week. This created a sort of customer loyalty as far as the programs were concerned, and a gradual shift in the cultural habits of the audience. The advertisements which were interwoven along with the main program also created a loyalty towards the products which were advertised. These factors permanently altered the social habits of the American society. Impact of Radio on large media companies: With the rise of compulsive consumerism brought about by the radio transmission of popular programs and advertisements, large media companies like NBC, and CBS sensed big business opportunities. The individual broadcasting stations got affiliated to national networks or were absorbed by big broadcasting chains, so that they could benefit from the economies of scale. The broadcast time was gradually increasing, By the middle of 1930's, many stations were using an airtime of 12 to 18 hours per day. This made it necessary for the broadcasters to fill the expanded airtime with variations of program types already developed. The large companies like NBC and CBS, also had to develop newer varieties of programs, like live performances by orchestras, talk shows, soap operas, and afternoon serial dramas. For this, they had to develop their own recording studios. Transcription, or pre-recorded music was also in vogue. To cut costs, these large companies bought the prerecorded music from transcription firms. The big companies were better placed financially, so they could command better quality of transcriptions, and also could afford to hire the best performers for their live shows. Although music was dominating the air time, emphasis by the network broadcasters was on transcriptions and not on classical music, whereas NBC could manage to broadcast a symphony orchestra with eminent musicians like the conductor of New York Philharmonic for many years, as opposed to the network operator who were mainly using transcriptions of music performances by local artistes. Similarly, CBS hired the services of actors, writers, poets etc to continue with high quality dramas and talk shows. Thus, the large media firms, who entered the broadcasting market, were able to continue with

Requirements for Admissible Statements Analysis Case Study

Requirements for Admissible Statements Analysis - Case Study Example On arresting, Escobedo was not warned of his Fifth Amendment Right according to which he had the right to remain silent. On reaching the police station, the arrested repeatedly asked to consult his lawyer but was denied. Even when his attorney arrived at the station, he was not allowed to see or speak his client. His lawyer was told by a police officer that he would be allowed to talk to him once they were done with him. Escobedo was told by a police officer that he and his sister would be released if he submitted to DiGerlando's statement. After hearing this, Escobedo did as he was told and on the basis of his statement he was tried in the court and found guilty of murder. His appeal was rejected by the Supreme Court of Illinois, and Escobedo then petitioned the U.S. Supreme Court for review of his conviction. In 1982, Oreste Fulminante's 11-year-old stepdaughter was reported missing by him. After two days of the report, her body was found in Arizona. She had been shot twice in the head. After some tine, Fulminante was arrested for an unrelated crime. While his stay at the prison, Fulminante met a fellow inmate, Anthony Sarivola, who was also a secret informant for the Federal Bureau of Investigation. O hearing about the murder of his step daughter, Sarivola asked Fulminate about what had happened. But Fulminate did nit give any statement. Sarivola then offered Fulminante protection from "tough treatment" or in other words, torture in prison, in exchange for a confession to the murder of Fulminante's stepdaughter. Fulminante agreed to this and confessed that he had murdered his step daughter. Sarivola passed this information to the Federal Bureau of Investigation. As a result of which, Fulminante was charged with first degree murder of her step daughter, and his confession to Sarivola was used against him at trial (Anonymous, 2009). Fulminante's motion of coerced confession was denied by the trial court and was convicted and sentenced to death. He appealed to the Arizona Supreme Court, where he stated that he was in danger of violence in the prison, had he not confessed murdering his step daughter. The Court held that the confession was indeed coerced and reasoned that a harmless error analysis was inappropriate in the case of forced confessions on the basis of the Fifth and the Fourteenth Amendments. The court ordered a new trial for Fulminante. Legal Requirements for Admissibility of Statements and their Applicability In order for a statement to be admissible in the court the Fifth, Sixth and the Fourteenth Amendment in the United States Constitution need to be fulfilled. The Fourteenth Amendment suggests Rights Guaranteed Privileges and Immunities of Citizenship, Due Process and Equal Protection. According to the Section 1 of this Amendment "All persons born or naturalized in the United States and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of

Educational Change Essay Example | Topics and Well Written Essays - 1000 words

Educational Change - Essay Example The value and effectiveness of education can only be realized by changing the entire system. Although current education is important in developing the society, it is not sufficient. In addition, contemporary education does not cover the cost that its beneficiaries pay to acquire it. Complexity of modern education in relation to the expectation of the real world is the main cause of low value in modern education. Current education needs to be changed in order to increase its value by eliminating complexity, improve application and to improve its ability to measure the intelligence and knowledge of an individual. Current schooling has many weaknesses that deny its beneficiaries the value for their investments in education. Although the flaws in existing education have been in existence for a long time, their impacts have not yet been analyzed. The education system was structured long time ago but the needs of the society have changed with time hence necessitating an overhaul change in the education system. (Hallinger, 2003). Effective changes on the current education can only be realized from a transformation of the entire educational system. Partial changes will leave loopholes or weakness on the resultant education system. It is worth noting that education is a multivariate concept and therefore, all facets should be given appropriate attention. Effectiveness of an education system lies in the ability to transform its beneficiaries and the entire society. Notably, education system focuses too much on theoretical aspects whereas the world has become more practical. Therefore, it is important to incorporate practical aspect in the education system in order to enable students handle practical life experiences once they leave the school. This is evident with most college graduates who never apply their education after completing their courses from various colleges (Hargreaves, 2004). The purpose of schooling is realized through application of acquired knowledge to solve real-world problems. Significance of education can therefore, be established by determining the rate of application of knowledge outside educational institutions (Hallinger, 2003). However, it has been found out that modern education system discourage application of knowledge in solving real-world problems. A lot of evidence supports that education system does not offer adequate skills needed for practical life experience. Most of the principles taught in school are either too complicated and complex to be applied in real life or are not adequate at all. This is particularly ironical since many resources have been applied to acquire these skills. It can be agreed that learning complicated skills is a waste of valuable time for students. This is because students spend their prime age in life acquiring life skills in school. If students are not able to apply the skills learned in school in real life, then it becomes a waste of time, energy, and resources. Changing the current ed ucation is important in order to incorporate the application aspect in contemporary education. Value of education can only be realized through application of the knowledge acquired through education. It is possible to view education as an investment since students will have to get returns once they start using the skills learned in school. With the rising economic crisis in many countries, investment in education becomes expensive both to the government and to individuals as well. Since beneficiaries of education use little if any of the skills gained from education in real life, then education becomes even more expensive. Simply put, return on investment on educations is not justified. The cost of education and the actual

Developing leadership challenges and solutions interviewing questions Assignment

Developing leadership challenges and solutions interviewing questions - Assignment Example One thing noted during the initial days after getting into the country that was quite different from UAE is that people stick to their families and do not even know who most of their neighbors are. They just choose to live isolated and do not care about the neighbor across the street unless the neighborhood is of a low-income level or middle-class. Not all middle-class neighborhoods appreciate people who come to knock at their doors but they also choose their favorites with whom they associate with greatly. In the event that the neighborhood is closely knit, the people will be inviting each other for barbeques and parties, and the neighbors always come with drinks and are ready to assist where they can to make the party a big event. The people here care about each other and are mainly divided by class. The level of participation in events in the country imply a great level of understanding that allows them to make good use of their skills as a way of creating the best moment in their lives that will remained etched into their minds until something else happens. In the UAE, the only life people have depends on the family values. Some families will have their extended families stay with them and the sharing of meals and events define their fun moments. In the US, the extended family mainly comes together once a year during thanksgiving and any more visits will be preplanned (Besamusca, 2011). In the UAE, families maintain close links with each other and define the importance of developing their ties further, appreciating what they do together. The children are also raised liberally, and that is different from what is practiced in the UAE. Children in the U.S. have a lot of freedom and some do not even listen to their parents because of the freedom accorded to them. They go to parties without their parents’ presence and some even indulge while at those parties. In the U.A.E., it is quite different. Strict discipline is used to raise children to be

Correctional Institution, Criminology major Essay

Correctional Institution, Criminology major - Essay Example Among them is â€Å"protection from cruel and unusual punishment, including sexual harassment and other sex crimes† (Jacobson 118). To discourage sexual abuse in a prison facility, a correctional manager could take some steps by efficiently using the limited resources at their disposal which may include increasing time deducted on sentences for good behavior. This would encourage prisoners to adhere to prison rules with the hope of early release. The prison manager should practice wise deployment of staff taking in consideration the vulnerable locations and high risk times. Rape is a violent crime, therefore, stopping violent activities reduces chances of rape occurring. A correctional manager should endeavor to stop prison gang membership, activity or recruitment. These gangs encourage violent behaviors and operate on codes of silence. The correctional manager should also develop effective institutional policies and processes. These should provide guidelines on what is to be done in case abuse is reported, suspected, found happening or proven. These policies and procedures should instruct on how to deal with of fenders and victims. They should guarantee swift action and protection for the victim. The correctional manager should also encourage programs that prepare prisoners to live a contributing and law-abiding life after incarceration. These programs may incorporate activities that put the prisoners in controlled contact with the free world. This gives them a hint of free life and encourages them to adhere to rules to avoid longer incarceration and pursue early parole. Rape and other sex crimes in prisons occur due to many reasons. Facilities where prisoners are over-crowded have higher incidences of sexual abuse (Freedman 89). Understaffing of correctional facilities makes it hard to monitor prisoners’ activities. This creates space for indulgence in illegal and unethical

Article #5 Joy in School by Steven Wolk Essay Example | Topics and Well Written Essays - 250 words

Article #5 Joy in School by Steven Wolk - Essay Example Coming up with new things gives a student sense of importance. They become empowered and given a chance to experience how demanding invention is (Wolk, 2010). Teachers should provide space in school and exhibit students’ original work. They can decide to place photographs of students against their work. A student comes up with ideas and teachers help to design and develop them. School space should be welcoming and lively. They give a feeling of freedom to learn than boredom and rigidity (Wolk, 2010). Students should have free areas where they can read from and discuss. They should be colorful to set in a vibrant and joyful sight. Students should be allowed to spend some time outdoors and interact with nature. Going for recess and having outdoor classes set them in a jovial mood. Reading of excellent books like story books gives joy to students since they are not too serious books. Arts and gym classes should be considered as valuable as the other classes. Students have different talents, which can only be realized if given a chance. Assessment in school should be made more friendly experience (Wolk, 2010). Students should be helped to learn that failure is part of