History.

In 1935, German physician Karl Matthes (1905–1962) developed the first two-wavelength ear O saturation meter with red and green filters (later red and infrared filters). His meter was the first device to measure O saturation.  The original oximeter was made by Glenn Allan Millikan in the 1940s. In 1949, Wood added a pressure capsule to squeeze blood out of the ear so as to obtain an absolute O saturation value when blood was readmitted. The concept is similar to today's conventional pulse oximetry, but was difficult to implement because of unstable photocells and light sources; today this method is not used clinically. In 1964 Shaw assembled the first absolute reading ear oximeter, which used eight wavelengths of light.  Pulse oximetry was developed in 1972, by Takuo Aoyagi and Michio Kishi, bioengineers, at Nihon Kohden using the ratio of red to infrared light absorption of pulsating components at the measuring site. Susumu Nakajima, a surgeon, and his associates first tested the device in patients, reporting it in 1975. It was commercialized by Biox in 1980.  By 1987, the standard of care for the administration of a general anesthetic in the U.S. included pulse oximetry. From the operating room, the use of pulse oximetry rapidly spread throughout the hospital, first to recovery rooms, and then to intensive care units. Pulse oximetry was of particular value in the neonatal unit where the patients do not thrive with inadequate oxygenation, but too much oxygen and fluctuations in oxygen concentration can lead to vision impairment or blindness from retinopathy of prematurity (ROP). Furthermore, obtaining an arterial blood gas from a neonatal patient is painful to the patient and a major cause of neonatal anemia. Motion artifact can be a significant limitation to pulse oximetry monitoring resulting in frequent false alarms and loss of data. This is because during motion and low peripheral perfusion, many pulse oximeters cannot distinguish between pulsating arterial blood and moving venous blood, leading to underestimation of oxygen saturation. Early studies of pulse oximetry performance during subject motion made clear the vulnerabilities of conventional pulse oximetry technologies to motion artifact.  In 1995, Masimo introduced Signal Extraction Technology (SET) that could measure accurately during patient motion and low perfusion by separating the arterial signal from the venous and other signals. Since then, pulse oximetry manufacturers have developed new algorithms to reduce some false alarms during motion such as extending averaging times or freezing values on the screen, but they do not claim to measure changing conditions during motion and low perfusion. So, there are still important differences in performance of pulse oximeters during challenging conditions. Also in 1995, Masimo introduced perfusion index, quantifying the amplitude of the peripheral plethysmograph waveform. Perfusion index has been shown to help clinicians predict illness severity and early adverse respiratory outcomes in neonates, predict low superior vena cava flow in very low birth weight infants, provide an early indicator of sympathectomy after epidural anesthesia, and improve detection of critical congenital heart disease in newborns.  Published papers have compared signal extraction technology to other pulse oximetry technologies and have demonstrated consistently favorable results for signal extraction technology. Signal extraction technology pulse oximetry performance has also been shown to translate into helping clinicians improve patient outcomes. In one study, retinopathy of prematurity (eye damage) was reduced by 58% in very low birth weight neonates at a center using signal extraction technology, while there was no decrease in retinopathy of prematurity at another center with the same clinicians using the same protocol but with non-signal extraction technology. Other studies have shown that signal extraction technology pulse oximetry results in fewer arterial blood gas measurements, faster oxygen weaning time, lower sensor utilization, and lower length of stay. The measure-through motion and low perfusion capabilities it has also allow it to be used in previously unmonitored areas such as the general floor, where false alarms have plagued conventional pulse oximetry. As evidence of this, a landmark study was published in 2010 showing that clinicians at Dartmouth-Hitchcock Medical Center using signal extraction technology pulse oximetry on the general floor were able to decrease rapid response team activations, ICU transfers, and ICU days. In 2020, a follow-up retrospective study at the same institution showed that over ten years of using pulse oximetry with signal extraction technology, coupled with a patient surveillance system, there were zero patient deaths and no patients were harmed by opioid-induced respiratory depression while continuous monitoring was in use.  In 2007, Masimo introduced the first measurement of the pleth variability index (PVI), which multiple clinical studies have shown provides a new method for automatic, noninvasive assessment of a patient's ability to respond to fluid administration. Appropriate fluid levels are vital to reducing postoperative risks and improving patient outcomes: fluid volumes that are too low (under-hydration) or too high (over-hydration) have been shown to decrease wound healing and increase the risk of infection or cardiac complications. Recently, the National Health Service in the United Kingdom and the French Anesthesia and Critical Care Society listed PVI monitoring as part of their suggested strategies for intra-operative fluid management.  In 2011, an expert workgroup recommended newborn screening with pulse oximetry to increase the detection of critical congenital heart disease (CCHD). The CCHD workgroup cited the results of two large, prospective studies of 59,876 subjects that exclusively used signal extraction technology to increase the identification of CCHD with minimal false positives. The CCHD workgroup recommended newborn screening be performed with motion tolerant pulse oximetry that has also been validated in low perfusion conditions. In 2011, the US Secretary of Health and Human Services added pulse oximetry to the recommended uniform screening panel. Before the evidence for screening using signal extraction technology, less than 1% of newborns in the United States were screened. Today, The Newborn Foundation has documented near universal screening in the United States and international screening is rapidly expanding. In 2014, a third large study of 122,738 newborns that also exclusively used signal extraction technology showed similar, positive results as the first two large studies.  High-resolution pulse oximetry (HRPO) has been developed for in-home sleep apnea screening and testing in patients for whom it is impractical to perform polysomnography. It stores and records both pulse rate and SpO2 in 1 second intervals and has been shown in one study to help to detect sleep disordered breathing in surgical patients.

Function.

A blood-oxygen monitor displays the percentage of blood that is loaded with oxygen. More specifically, it measures what percentage of hemoglobin, the protein in blood that carries oxygen, is loaded. Acceptable normal ranges for patients without pulmonary pathology are from 95 to 99 percent. For a patient breathing room air at or near sea level, an estimate of arterial pO can be made from the blood-oxygen monitor "saturation of peripheral oxygen" (SpO) reading.  A typical pulse oximeter uses an electronic processor and a pair of small light-emitting diodes (LEDs) facing a photodiode through a translucent part of the patient's body, usually a fingertip or an earlobe. One LED is red, with wavelength of 660 nm, and the other is infrared with a wavelength of 940 nm. Absorption of light at these wavelengths differs significantly between blood loaded with oxygen and blood lacking oxygen. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated hemoglobin allows more infrared light to pass through and absorbs more red light. The LEDs sequence through their cycle of one on, then the other, then both off about thirty times per second which allows the photodiode to respond to the red and infrared light separately and also adjust for the ambient light baseline.  The amount of light that is transmitted (in other words, that is not absorbed) is measured, and separate normalized signals are produced for each wavelength. These signals fluctuate in time because the amount of arterial blood that is present increases (literally pulses) with each heartbeat. By subtracting the minimum transmitted light from the transmitted light in each wavelength, the effects of other tissues are corrected for, generating a continuous signal for pulsatile arterial blood. The ratio of the red light measurement to the infrared light measurement is then calculated by the processor (which represents the ratio of oxygenated hemoglobin to deoxygenated hemoglobin), and this ratio is then converted to SpO by the processor via a lookup table based on the Beer–Lambert law. The signal separation also serves other purposes: a plethysmograph waveform ("pleth wave") representing the pulsatile signal is usually displayed for a visual indication of the pulses as well as signal quality, and a numeric ratio between the pulsatile and baseline absorbance ("perfusion index") can be used to evaluate perfusion.

Indication.

A pulse oximeter is a medical device that indirectly monitors the oxygen saturation of a patient's blood (as opposed to measuring oxygen saturation directly through a blood sample) and changes in blood volume in the skin, producing a photoplethysmogram that may be further processed into other measurements. The pulse oximeter may be incorporated into a multiparameter patient monitor. Most monitors also display the pulse rate. Portable, battery-operated pulse oximeters are also available for transport or home blood-oxygen monitoring.

Advantages.

Pulse oximetry is particularly convenient for noninvasive continuous measurement of blood oxygen saturation. In contrast, blood gas levels must otherwise be determined in a laboratory on a drawn blood sample. Pulse oximetry is useful in any setting where a patient's oxygenation is unstable, including intensive care, operating, recovery, emergency and hospital ward settings, pilots in unpressurized aircraft, for assessment of any patient's oxygenation, and determining the effectiveness of or need for supplemental oxygen. Although a pulse oximeter is used to monitor oxygenation, it cannot determine the metabolism of oxygen, or the amount of oxygen being used by a patient. For this purpose, it is necessary to also measure carbon dioxide (CO) levels. It is possible that it can also be used to detect abnormalities in ventilation. However, the use of a pulse oximeter to detect hypoventilation is impaired with the use of supplemental oxygen, as it is only when patients breathe room air that abnormalities in respiratory function can be detected reliably with its use. Therefore, the routine administration of supplemental oxygen may be unwarranted if the patient is able to maintain adequate oxygenation in room air, since it can result in hypoventilation going undetected.  Because of their simplicity of use and the ability to provide continuous and immediate oxygen saturation values, pulse oximeters are of critical importance in emergency medicine and are also very useful for patients with respiratory or cardiac problems, especially COPD, or for diagnosis of some sleep disorders such as apnea and hypopnea. Portable battery-operated pulse oximeters are useful for pilots operating in non-pressurized aircraft above or in the U.S. where supplemental oxygen is required. Portable pulse oximeters are also useful for mountain climbers and athletes whose oxygen levels may decrease at high altitudes or with exercise. Some portable pulse oximeters employ software that charts a patient's blood oxygen and pulse, serving as a reminder to check blood oxygen levels.  Connectivity advancements have made it possible for patients to have their blood oxygen saturation continuously monitored without a cabled connection to a hospital monitor, without sacrificing the flow of patient data back to bedside monitors and centralized patient surveillance systems.

Limitations.

Pulse oximetry solely measures hemoglobin saturation, not ventilation and is not a complete measure of respiratory sufficiency. It is not a substitute for blood gases checked in a laboratory, because it gives no indication of base deficit, carbon dioxide levels, blood pH, or bicarbonate (HCO) concentration. The metabolism of oxygen can be readily measured by monitoring expired CO, but saturation figures give no information about blood oxygen content. Most of the oxygen in the blood is carried by hemoglobin; in severe anemia, the blood contains less hemoglobin, which despite being saturated cannot carry as much oxygen.  Erroneously low readings may be caused by hypoperfusion of the extremity being used for monitoring (often due to a limb being cold, or from vasoconstriction secondary to the use of vasopressor agents); incorrect sensor application; highly calloused skin; or movement (such as shivering), especially during hypoperfusion. To ensure accuracy, the sensor should return a steady pulse and/or pulse waveform. Pulse oximetry technologies differ in their abilities to provide accurate data during conditions of motion and low perfusion.  Pulse oximetry also is not a complete measure of circulatory oxygen sufficiency. If there is insufficient bloodflow or insufficient hemoglobin in the blood (anemia), tissues can suffer hypoxia despite high arterial oxygen saturation.  Since pulse oximetry measures only the percentage of bound hemoglobin, a falsely high or falsely low reading will occur when hemoglobin binds to something other than oxygen:  A noninvasive method that allows continuous measurement of the dyshemoglobins is the pulse CO-oximeter, which was built in 2005 by Masimo. By using additional wavelengths, it provides clinicians a way to measure the dyshemoglobins, carboxyhemoglobin, and methemoglobin along with total hemoglobin.

Increasing usage.

According to a report by iData Research the U.S. pulse oximetry monitoring market for equipment and sensors was over in 2011.  In 2008, more than half of the major internationally exporting medical equipment manufacturers in China were producers of pulse oximeters.

Early detection of COVID-19.

Pulse oximeters are used to help with the early detection of COVID-19 infections, which may cause initially unnoticeable low arterial oxygen saturation and hypoxia. "The New York Times" reported that "health officials are divided on whether home monitoring with a pulse oximeter should be recommended on a widespread basis during Covid-19. Studies of reliability show mixed results, and there’s little guidance on how to choose one. But many doctors are advising patients to get one, making it the go-to gadget of the pandemic."

Derived measurements.

Due to changes in blood volumes in the skin, a plethysmographic variation can be seen in the light signal received (transmittance) by the sensor on an oximeter. The variation can be described as a periodic function, which in turn can be split into a DC component (the peak value) and an AC component (peak minus valley). The ratio of the AC component to the DC component, expressed as a percentage, is known as the (peripheral) perfusion index (Pi) for a pulse, and typically has a range of 0.02% to 20%. An earlier measurement called the pulse oximetry plethysmographic (POP) only measures the "AC" component, and is derived manually from monitor pixels.  Pleth variability index (PVI) is a measure of the variability of the perfusion index, which occurs during breathing cycles. Mathematically it is calculated as, where the maximum and minimum Pi values are from one or many breathing cycles. It has been shown to be a useful, noninvasive indicator of continuous fluid responsiveness for patients undergoing fluid management. Pulse oximetry plethysmographic waveform amplitude (ΔPOP) is an analogous earlier technique for use on the manually-derived POP, calculated as.

Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation. Though its reading of peripheral oxygen saturation (Sp) is not always identical to the more desirable reading of arterial oxygen saturation (Sa) from arterial blood gas analysis, the two are correlated well enough that the safe, convenient, noninvasive, inexpensive pulse oximetry method is valuable for measuring oxygen saturation in clinical use.

Die Pulsoxymetrie oder Pulsoximetrie ist ein Verfahren zur nichtinvasiven Ermittlung der arteriellen Sauerstoffsättigung über die Messung der Lichtabsorption bzw. der Lichtremission bei Durchleuchtung der Haut (perkutan). Das Pulsoxymeter stellt ein speziell auf diese Anwendung optimiertes Spektralphotometer dar. Nebenbei dienen die verwendeten Geräte auch zur gleichzeitigen Pulsfrequenzkontrolle.


Evolution.

DECnet refers to a specific set of hardware and software networking products which implement the DIGITAL Network Architecture (DNA). The DIGITAL Network Architecture has a set of documents which define the network architecture in general, state the specifications for each layer of the architecture, and describe the protocols which operate within each layer. Although network protocol analyzer tools tend to categorize all protocols from DIGITAL as "DECnet", strictly speaking, non-routed DIGITAL protocols such as LAT, SCS, AMDS, LAST/LAD are not DECnet protocols and are not part of the DIGITAL Network Architecture.  To trace the evolution of DECnet is to trace the development of DNA. The beginnings of DNA were in the early 1970s. DIGITAL published its first DNA specification at about the same time that IBM announced its Systems Network Architecture (SNA). Since that time, development of DNA has evolved through the following phases:  Phase I (1974) Support limited to two PDP-11s running the RSX-11 operating system only, with communication over point-to-point (DDCMP) links between nodes.  Phase II (1975) Support for networks of up to 32 nodes with multiple, different implementations which could inter-operate with each other. Implementations expanded to include RSTS, TOPS-10 and TOPS-20 with communications between processors still limited to point-to-point links only. Introduction of downline loading (MOP), and file transfer using File Access Listener (FAL), remote file access using Data Access Protocol (DAP), task-to-task programming interfaces and network management features.  Phase III (1980). Support for networks of up to 255 nodes over point-to point and multi-drop links. Introduction of adaptive routing capability, record access, a network management architecture, and gateways to other types of networks including IBM’s SNA and CCITT Recommendation X.25.  Phase IV and Phase IV+ (1982). Phase IV was released initially to RSX-11 and VMS systems, later TOPS-20, TOPS-10, ULTRIX, VAXELN, and RSTS/E gained support. Support for networks of up to 64,449 nodes (63 areas of 1023 nodes), datalink capabilities expanded beyond DDCMP to include Ethernet local area network support as the datalink of choice, expanded adaptive routing capability to include hierarchical routing (areas, level 1 and level 2 routers), VMScluster support (cluster alias) and host services (CTERM). CTERM allowed a user on one computer to log into another computer remotely, performing the same function that Telnet does in the TCP/IP protocol stack. Digital also released a product called the PATHWORKS client, and more commonly known as the PATHWORKS 32 client, that implemented much of DECnet Phase IV for DOS, and 16 and 32 bit Microsoft Windows platforms (all the way through to Windows Server 2003).  Phase IV implemented an 8 layer architecture similar to the OSI (7 layer) model especially at the lower levels. Since the OSI standards were not yet fully developed at the time, many of the Phase IV protocols remained proprietary.  The Ethernet implementation was unusual in that the software changed the physical address of the Ethernet interface on the network to AA-00-04-00-xx-yy where xx-yy reflected the DECnet network address of the host. This allowed ARP-less LAN operation because the LAN address could be deduced from the DECnet address. This precluded connecting two NICs from the same DECnet node onto the same LAN segment, however.  The initial implementations released were for VMS and RSX-11, later this expanded to virtually every operating system DIGITAL ever shipped with the notable exception of RT-11. DECnet stacks are found on Linux, SunOS and other platforms, and Cisco and other network vendors offer products that can cooperate with and operate within DECnet networks. Full DECnet Phase IV specifications are available.  At the same time that DECnet Phase IV was released, the company also released a proprietary protocol called LAT for serial terminal access via Terminal servers. LAT shared the OSI physical and datalink layers with DECnet and LAT terminal servers used MOP for the server image download and related bootstrap processing.  Enhancements made to DECnet Phase IV eventually became known as DECnet Phase IV+, although systems running this protocol remained completely interoperable with DECnet Phase IV systems.  Phase V and Phase V+ (1987). Support for very large (architecturally unlimited) networks, a new network management model, local or distributed name service, improved performance over Phase IV. Move from a proprietary network to an Open Systems Interconnection (OSI) by integration of ISO standards to provide multi-vendor connectivity and compatibility with DNA Phase IV, the last two features resulted in a hybrid network architecture (DNA and OSI) with separate “towers” sharing an integrated transport layer. Transparent transport level links to TCP/IP were added via the IETF RFC 1006 (OSI over IP) and RFC 1859 (NSP over IP) standards "(see diagram)".  It was later renamed DECnet/OSI to emphasize its OSI interconnectibility, and subsequently DECnet-Plus as TCP/IP protocols were incorporated.

Notable installations.

DEC Easynet.

DEC's internal corporate network was a DECnet network called Easynet, which had evolved from DEC's Engineering Net (E-NET). It included over 2,000 nodes as of 1984, 15,000 nodes (in 39 countries) as of 1987, and 54,000 nodes as of 1990.

The DECnet Internet.

DECnet was used at various scientific research centers which linked their networks to form an international network called the DECnet Internet. This included the U.S. Space Physics Analysis Network (US-SPAN), the European Space Physics Analysis Network (E-SPAN), and other research and education networks. The network consisted of over 17,000 nodes as of 1989. Routing between networks with different address spaces involved the use of either "poor man's routing" (PMR) or address translation gateways. In December 1988, VAX/VMS hosts on the DECnet Internet were attacked by the Father Christmas worm.

CCNET.

CCNET (Computer Center Network) was a DECnet network that connected the campuses of various universities in the eastern regions of the United States during the 1980s. A key benefit was the sharing of systems software developed by the operations staff at the various sites, all of which were using a variety of DEC computers. As of March 1983, it included Columbia University, Carnegie Mellon University, and Case Western Reserve University. By May 1986, New York University, Stevens Institute of Technology, Vassar College and Oberlin College had been added. Several other universities joined later.

Hobbyist DECnet networks.

Hobbyist DECnet networks have been in use during the 21st century. These include:

DECnet is a suite of network protocols created by Digital Equipment Corporation. Originally released in 1975 in order to connect two PDP-11 minicomputers, it evolved into one of the first peer-to-peer network architectures, thus transforming DEC into a networking powerhouse in the 1980s. Initially built with three layers, it later (1982) evolved into a seven-layer OSI-compliant networking protocol.

DECnet ist ein homogenes Lokales Netzwerk, das die Firma Digital Equipment Corporation (kurz DEC) im Jahr 1975 eingeführt hat, um ihre Minicomputer zu vernetzen. Es besteht aus einer Reihe von Netzwerkprotokollen, die in ihrer Gesamtheit als DIGITAL Network Architecture (DNA) bezeichnet werden. DECnet wurde kompatibel zu Ethernet, X.25 und IBMs SNA gemacht, so dass sich damit auch die DEC-Rechner mit Computern anderer Hersteller vernetzen lassen.


History.

The hall of fame and museum are located in the Newport Casino, which was commissioned in 1879 by James Gordon Bennett Jr. as part of an exclusive resort for wealthy Newport summer residents. It was designed by Charles McKim along with Stanford White, who did the interiors. It is an example of Victorian Shingle Style architecture. In 1881, the Real Tennis Court (housing the National Tennis Club) and the Casino Theatre were constructed at the east end of the campus. The club was opened on July 1, 1880 after a six-month construction period and quickly became a fashionable venue for Newport summer residents.  The United States Lawn Tennis Association held its first championships at the Newport Casino in 1881. The event was held annually through 1914, by which time tennis had become the key attraction at the resort. The championship was suspended during World War I.  But by the 1950s, the retreat was struggling financially, as tourism preferences changed. It was at risk of being demolished for redevelopment of modern retail space, but the building was purchased and saved by Jimmy and Candy Van Alen, wealthy Newport summer residents. A sportsman himself, in 1954, Jimmy Van Alen established the Tennis Hall of Fame and Museum in the Casino. The combination of tennis matches and the museum allowed the building to be saved. Van Alen intended the facility to be "a shrine to the ideals of the game", and was elected president of the hall in 1957. The International Tennis Hall of Fame was officially sanctioned by the United States Tennis Association at its foundation in 1954. It was recognized by the International Tennis Federation in 1986. The first Hall of Fame members were inducted in 1955; as of 2017, a total of 252 inductees from 23 countries have been recognized..  In 2015, Martina Hingis was appointed as the first Global Ambassador for the International Tennis Hall of Fame. The current Board of Governors includes former professional tennis players Todd Martin, Stan Smith and Katrina Adams.

Collection.

The museum houses a large collection of artifacts and memorabilia – including videos, photographs, audio recordings, tennis equipment and apparel, trophies, and art – highlighting the history of tennis from its origins up through the modern era. The collection is displayed year-round in the museum's of exhibit space.

Hall of Fame Tennis Championships.

The Hall of Fame hosts several tournaments, including the Hall of Fame Tennis Championships. Part of the men's ATP World Tour, the tournament is the only grass court event in North America. Top male players come to Newport directly from Wimbledon to compete for the Van Alen Cup at the International Tennis Hall of Fame. Past champions include Americans John Isner, and Mardy Fish, as well as two-time champion Fabrice Santoro of France.

The International Tennis Hall of Fame is located in Newport, Rhode Island, United States. It honors both players and other contributors to the sport of tennis. The complex, the former Newport Casino, includes a museum, grass tennis courts, an indoor tennis facility, and a court tennis (or real tennis) facility.

Die International Tennis Hall of Fame (eigentlich International Tennis Hall of Fame & Museum) ist ein Tennismuseum im Newport Casino in Newport, Rhode Island, USA.


Early life.

William Patrick Corgan, Jr. was born at Columbus Hospital in the Lincoln Park neighborhood of Chicago on March 17, 1967, the oldest son of guitarist William Corgan Sr. and his wife Martha Louise Maes Corgan Lutz. He was raised Catholic and is of Irish descent. His parents had one more son, Ricky, before divorcing in 1970. His father was remarried to a flight attendant, and Corgan and his brother went to live with them in Glendale Heights, Illinois. Corgan alleges that his stepmother was abusive to him, both physically and emotionally. He developed a protective bond with his younger paternal half-brother, who had special needs as a child. When Corgan's father and stepmother separated, all three boys lived alone with their stepmother, and both of his birth parents lived separately within an hour's drive.  Corgan, who grew much faster than his fellow students, was a strong athlete in elementary school. In addition to being a member of his baseball team at Marquardt Middle School, he amassed over 10,000 baseball cards and listened to every Chicago Cubs game on the radio. However, by the time he began attending Glenbard North High School, his athletic prowess had greatly diminished. He decided to start playing guitar after seeing a Flying V when he went over to a friend's house. Corgan gave his savings to his father, who bought him a used Les Paul knock-off. His father encouraged him to listen to Jeff Beck and Jimi Hendrix, but offered little other support, so he taught himself to play the instrument. His musical interests in his formative years included hard rock like "Guts"-era John Cale, heavy metal pioneers Black Sabbath, and mainstream rock like Queen, Boston, ELO, Rush, and Cheap Trick. In high school, Corgan discovered alternative rock through Bauhaus and The Cure. He performed in a string of bands in high school and graduated as an honor student. Despite grant and scholarship offers from a number of schools, and a tuition fund left by his grandmother, Corgan decided to pursue music full-time.

Music career.

1985–1987: Early career.

Not finding the Chicago music scene to his liking, Corgan moved to St. Petersburg, Florida in 1985 with his first major band, The Marked (so named for the conspicuous birthmarks of both Corgan and drummer Ron Roesing). Not finding success in St. Petersburg, the band dissolved; Corgan moved back to Chicago to live with his father. From 1987 to 1988, he played guitar in Chicago band Deep Blue Dream, which also featured future Static-X frontman Wayne Static. He left the band to focus on The Smashing Pumpkins.

1988–2000: The Smashing Pumpkins.

Upon his return to Chicago, Corgan had already devised his next project – a band that would be called The Smashing Pumpkins. Corgan met guitarist James Iha while working in a record store, and the two began recording demos, which Corgan describes as "gloomy little goth-pop records". He met bassist D'arcy Wretzky after a local show, arguing with her about a band that had just played, The Dan Reed Network. Soon after, the Smashing Pumpkins were formed. The trio began to play together at local clubs with a drum machine for percussion. To secure a show at the Metro in Chicago, the band recruited drummer Jimmy Chamberlin, and played for the first time as a quartet on October 5, 1988. The addition of Chamberlin drove the band in a heavier direction almost immediately. On the band's debut album, "Gish" (1991), the band integrated psychedelic rock and heavy metal into their sound. "Gish" fared better than expected, but the follow-up, "Siamese Dream", released on Virgin Records in 1993, became a multi-platinum hit. The band became known for internal drama during this period, with Corgan frequently characterized in the music press as a "control freak" due to rumors that Corgan played all the guitar and bass parts on "Siamese Dream" (a rumor that Corgan later confirmed as true). Despite this, the album was well received by critics, and the songs "Today", "Cherub Rock", and "Disarm" became hits.  The band's 1995 follow-up effort, the double album "Mellon Collie and the Infinite Sadness", was more successful, spawning a string of hit singles. According to Jon Pareles from "The New York Times", Corgan wanted to "lose himself and find himself..." in this album. The album was nominated for seven Grammy awards that year, and would eventually be certified ten times platinum in the United States. The song "1979" was Corgan's biggest hit to date, reaching No. 1 on "Billboard"'s modern rock and mainstream rock charts. Their appearance on "Saturday Night Live" on November 11, 1995, to promote this material (their second appearance on the show overall) was also the television debut appearance of Corgan's shaved head, which he has maintained consistently since.  On July 12, 1996, touring keyboardist Jonathan Melvoin died in a Manhattan hotel room of a heroin overdose after he and Chamberlin used the drug together. Chamberlin was later arrested on a misdemeanor drug possession charge. The Smashing Pumpkins made the decision to fire Chamberlin and continue as a trio. This shakeup, coupled with Corgan going through a divorce and the death of his mother, influenced the somber mood of the band's next album, 1998's "Adore". Featuring a darker, more subdued and heavily electronic sound at a time when alternative rock was declining in mainstream cachet, "Adore" divided both critics and fans, resulting in a significant decrease in album sales (it sold 1.3 million discs in the US). Chamberlin was reunited with the band in 1999. In 2000, they released "Machina/The Machines of God", a concept album on which the band deliberately played to their public image. Critics were again divided, and sales were lower than before; "Machina" is the second lowest-selling commercially released Smashing Pumpkins album to date, with U.S. sales of 583,000 units up to 2005. During the recording for "Machina", Wretzky quit the band and was replaced for the upcoming tour by former Hole bassist Melissa Auf der Maur. In 2000 the band announced they would break up at the end of the year, and soon after released "Machina II/The Friends & Enemies of Modern Music" free over the Internet. The Smashing Pumpkins played their last show on December 2, 2000, at the Cabaret Metro.

2001–2005: Zwan and solo career.

Following a brief stint touring with New Order in the summer, Corgan reunited with Chamberlin to form the band Zwan with Corgan's old friend Matt Sweeney in late 2001. According to Neil Strauss of New York Times, during his few live performances with the band, Corgan says "is still a work in progress". The lineup was completed with guitarist David Pajo and bassist Paz Lenchantin. The band had two distinct incarnations, the primary approach being an upbeat rock band with a three-guitar-driven sound, the second, a folk and gospel inspired acoustic side with live strings. The quintet performed throughout 2002, and their debut album, "Mary Star of the Sea", was released in early 2003 to generally positive reviews. In the midst of their supporting tour for the album, mounting conflict between Corgan and Chamberlin, and the other band members led to the cancellation of the rest of the tour as the band entered an apparent hiatus, formally announcing a breakup in September 2003.  In 2004, Corgan began writing revealing autobiographical posts on his website and his MySpace page, blaming Iha for the breakup of the Smashing Pumpkins, calling Wretzky "a mean spirited drug addict," and criticizing his former Zwan bandmates' fixation with "indie cred" and calling them "filthy", opportunistic, and selfish.  On September 17, 2003, Billy presented his poetry at the Art Institute of Chicago's Rubloff Auditorium. In late 2004, Corgan published "Blinking with Fists", a book of poetry. Despite mixed reviews, the book debuted on the New York Times Best Seller list. Around this time, he began posting autobiographical writings online under the title "The Confessions of Billy Corgan".  Also in 2004, he began a solo music career, landing on an electronic/shoegaze/alternative rock sound for his first solo album, "TheFutureEmbrace", co-produced and arranged by Bon Harris of Nitzer Ebb. Released on June 21, 2005, through Reprise Records, it garnered mixed reviews from the press and only sold 69,000 copies. Corgan toured behind his solo album with a touring band that included Linda Strawberry, Brian Liesegang and Matt Walker in 2005. This tour was not as extensive as previous Smashing Pumpkins or Zwan tours. Prior to recording "TheFutureEmbrace", Corgan had recorded some 72 songs inspired by Chicago history for the largely acoustic "ChicagoSongs" project, which have yet to be released.

2005–present: The Smashing Pumpkins revival.

In 2005, Corgan took out a full-page ad in Chicago's two major newspapers ("The Chicago Tribune" and "The Chicago Sun-Times") revealing his desire to re-form the Smashing Pumpkins. Several days later, Jimmy Chamberlin accepted Corgan's offer for a reunion.  On April 20, 2006, the band's official website confirmed that the group was indeed reuniting. The re-formed Smashing Pumpkins went into studio for much of 2006 and early 2007, and performed its first show in seven years on May 22, 2007, with new members Ginger Pooley (bass) and Jeff Schroeder (guitar) replacing Wretzky and Iha. The new album, titled "Zeitgeist," was released in the United States on July 10, 2007, and debuted at No. 2 on the "Billboard" charts. Corgan and the rest of the Pumpkins toured extensively throughout 2007 and 2008, also releasing the EP "American Gothic" and the singles "G.L.O.W." and "Superchrist". Chamberlin left the band in March 2009, and Corgan elected to continue under the name.  In summer 2009 Corgan formed the band Spirits in the Sky to play a tribute concert to the late Sky Saxon of the Seeds. He toured with the band, composed of ex-Catherine member and "Superchrist" producer Kerry Brown, the Electric Prunes bassist Mark Tulin, Strawberry Alarm Clock keyboardist Mark Weitz, frequent Corgan collaborator Linda Strawberry, flautist Kevin Dippold, "Superchrist" violinist Ysanne Spevack, saxist Justin Norman, new Pumpkins drummer Mike Byrne, and Jane's Addiction guitarist Dave Navarro, playing covers and new Pumpkins material at several clubs in California. At the end of the tour, Corgan, Byrne, Tulin, and Brown headed back to Chicago to begin work on the new Smashing Pumpkins album, "Teargarden by Kaleidyscope". The lineup at the time which included new bassist Nicole Fiorentino, toured through much of 2010, then spent 2011 recording the "album-within-an-album" "Oceania" and mounting tours of the United States and Europe. However, Byrne and Fiorentino would later leave the band in 2014.  In April Corgan announced a new solo record of "experimental" recordings he made in 2007, via the Smashing Pumpkins' website. The album, which he titled "AEGEA," was released exclusively on vinyl, with 250 copies being made. Most of those copies were sold online, and a few copies were sold at Madame Zuzu's teahouse in Chicago. The album was released on May 15.  On July 25, 2014, Corgan announced that the tapes from his "Siddhartha" show from March 2014 were being transferred for sale, much in the vein of "AEGEA." The set was expected to contain between 5 and 6 discs.  During the summer 2014, Corgan recorded The Smashing Pumpkins's tenth studio album, "Monuments to an Elegy," with Tommy Lee and Jeff Schroeder. The album was released in early December 2014.  In September 2015, Corgan started a blog of vintage photographs that he himself curated, and which he called "People and Their Cars". The website also included an email listing for the blog, titled "The Red Border Club". This list was to be used for information on upcoming People and Their Cars and "Hexestential" books and merchandise, along with access to additional images.  On September 8, 2016, Corgan announced, in a Facebook live video, that he had recorded a new solo album with producer Rick Rubin, and it would consist of 12 or 13 tracks. He described work on the album as being near completion, though a release date was not given.  On August 22, 2017, he announced the solo album, giving its title as "Ogilala."  On February 16, 2018, Corgan announced a reunion tour for The Smashing Pumpkins. The lineup consists of himself, James Iha, Jimmy Chamberlin, and Jeff Schroeder. It is rumored that former bassist D'arcy Wretzky was not a part of the lineup due to unresolved tension between her and Corgan. However, she has stated that after offering her a contract, Corgan retracted it, saying that "we also have to balance the forces at play... there is no room for error." After Wretzky released text messages between her and Corgan, a feud ensued, with each party attacking each other with biting remarks.  On November 22, 2019, Corgan released his third solo album "Cotillions", which he called "a labor of love". He also said, "This is absolutely an album from my heart."

Professional wrestling career.

Resistance Pro Wrestling (2011–2014).

In 2011 Corgan formed a Chicago-based independent wrestling promotion called Resistance Pro. Two years later, in 2013, he starred in a commercial for Walter E. Smithe Furniture, using the platform to promote his wrestling company.  In March 2014 it was reported that Corgan was in discussions with American television channel AMC to develop an unscripted reality series about Resistance Pro. The premise being a behind-the-scenes look at the promotion as Corgan "takes over creative direction for the independent wrestling company". The show was given the green light by AMC, under the working title of "Untitled Billy Corgan Wrestling Project," the same month.

Total Nonstop Action Wrestling (2015–2016).

In April 2015 Corgan was announced as the new Senior Producer of Creative and Talent Development for Total Nonstop Action Wrestling (TNA), where his role was to "develop characters and create story lines", which he has called "a dream come true". In August 2016, Corgan took over as the promotion's new president.  In November 2016 Corgan had left TNA after disputes about not being paid on time, and subsequently, Anthem Sports & Entertainment Corp and Impact Ventures, parent company of TNA Impact Wrestling, announced that Anthem has provided a credit facility to TNA to fund operations.  On November 11, Corgan signed a settlement with Anthem – TNA and Anthem announced that they would be repaying TNA's loan from Corgan.  Newly appointed TNA/Impact Wrestling President Ed Nordholm credits the invention of and the vision behind the Matt Hardy "Broken" gimmick to Jeremy Borash, David Lagana and Billy Corgan. While Borash specifically had the most input into the gimmick of the three aside from Matt, the Hardy family deny that Borash was the sole person behind the gimmick.

National Wrestling Alliance (2017–present).

On May 1, 2017, it was reported that Corgan had agreed to purchase the National Wrestling Alliance (NWA), including its name, rights, trademarks and championship belts. The purchase was confirmed by NWA president Bruce Tharpe later that same day. Corgan's ownership took effect on October 1, 2017.

Personal life.

For much of his life, Corgan has struggled with anxiety, depression, panic attacks, self-harm, OCD, and suicidal ideation. He attributes these problems to the abuse he endured as a child at the hands of his stepmother, as well as personal troubles and other issues. He has since become an advocate for abuse support networks. His mother Martha died in December 1996. The song "For Martha", from "Adore", was written in her memory. In the early 2000s Corgan named his label Martha's Music after her as well. A picture of Martha as a little girl sitting on a fake moon at Riverview Park is featured on the flipside of the "Siamese Dream" booklet.  Corgan is a keen supporter of the Chicago Cubs, and an occasional commentator on the team for WXRT DJ Lin Brehmer. He has appeared at many Cubs games, occasionally throwing the ceremonial first pitch or singing "Take Me Out to the Ballgame". He is also a fan of the Chicago Bulls and Chicago Blackhawks, and became personal friends with Dennis Rodman and Chris Chelios. He is an avid professional wrestling fan, and appeared at an ECW event wielding an acoustic guitar as a weapon. In 2008, the Pumpkins song "Doomsday Clock" was used by ROH for promotional videos. On April 26, 2010, Corgan appeared on the SIRIUS Satellite Radio program "Right After Wrestling" with Arda Ocal to discuss his love for wrestling and the importance of unique theme songs for characters. On August 26, 2010, he took part in a storyline with AAA during a concert for MTV World Stage. As far as other entertainment, Corgan once commented that all he watches on TV are "sports and the Three Stooges". In March 2008, he was spotted in the crowd at the final day of the cricket test match between New Zealand and England.  Corgan accepts some parts of Catholicism. In 2009, he launched Everything From Here to There, an interfaith website that is devoted to "Mind-Body-Soul" integration. He mentions praying each morning and night to be able to see through Jesus Christ's eyes and feel with His heart. An analysis of the symbolism of Corgan's lyrics considered the blend of beliefs he has cited in various interviews, which include ideas about religion, multiple dimensions, and psychic phenomena. He has claimed to have had multiple encounters with people who have the ability to shapeshift.  In 1993, Corgan married art conservator and artist Chris Fabian, his longtime on-again, off-again girlfriend. They were married at a small ceremony at his house in Wrigleyville. Corgan and Fabian separated in late 1995, and divorced in 1997. He refused to discuss the subject in interviews, saying, "There is not and will not be any public record on my marriage – that's one thing I have to draw lines around." He nevertheless described the circumstances of his marriage in his online "Confessions" LiveJournal post in 2005. In late 1995, Corgan started dating Ukrainian photographer Yelena Yemchuk, who later contributed to several Smashing Pumpkins videos and album art. He continued to date Yemchuk until around 2004. According to Corgan, his breakup with her contributed to the themes of his 2005 solo release "TheFutureEmbrace". In 2008, he blamed his dedication to music for what he called "a bad marriage and seven bad girlfriends in a row".  In 2005, Corgan dated musician Emilie Autumn for a number of months. The pair collaborated on multiple occasions during this time, with Autumn providing vocals and violin on his solo album and costume for a supporting music video. In early 2006, Corgan moved in with Courtney Love and her daughter. According to Love, he had his own wing in her Hollywood Hills mansion. Two years later, Love criticized him publicly over his alleged refusal to attend her daughter's sweet 16 party. After they parted ways, Corgan stated in a March 2010 interview, "I have no interest in supporting [Love] in any way, shape or form. You can't throw enough things down the abyss with a person like that." Shortly after, when her band's album "Nobody's Daughter" was released, Corgan used Twitter to post anger-filled rants against her in reference to two songs he had written, "Samantha" and "How Dirty Girls Get Clean", which ended up on the album without his permission. Love then wrote an apology to him on her Facebook account, but the feud continued. Corgan took to Twitter to rant against her again. She responded to him on Twitter, saying, "All i am is nice about you so if you wanna be mean be mean i don't feel anything. i have too much to feel dear."  Corgan said after the 2008 U.S. presidential election, "I'm very proud of my country right now for doing the right thing." He has since said that he was disappointed with Barack Obama's presidency, and that he lacks faith in both major political parties. In 2009, he posted a transcript of a webcast by political activist Lyndon LaRouche to the official Smashing Pumpkins forum. In 2016, he called progressive political campaigners "social justice warriors"; compared them to Maoists, cult members, and the KKK; and said they were a threat to freedom of speech. In 2018, he called himself a "free-market libertarian capitalist" and added that he has not voted since 1992, when he voted for Bill Clinton. On March 10, 2009, Corgan testified in front of Congress on behalf of the musicFIRST Coalition. He spoke in favor of H.R. 848, the Performance Rights Act, which gives musicians and artists their share of compensation when their music is played on radio stations.  In 2009, Corgan was linked with pop star Jessica Simpson. He started dating Australian singer Jessica Origliasso in 2010, and remained in a relationship with her until early June 2012. Origliasso blamed their split on their careers forcing them to spend too much time apart. He began dating Chloe Mendel in 2013. She gave birth to a son named Augustus Juppiter Corgan on November 16, 2015. Their second child, a daughter named Philomena Clementine Corgan, was born on October 2, 2018.  Corgan adopted a pescetarian diet in 2013, and stated in 2017 that he had begun following a vegan and gluten-free diet. In 2012, he opened a tea house in his native Highland Park called Madame Zuzu's Tea House.

Collaborations.

In addition to performing, Corgan has produced albums for Ric Ocasek, The Frogs, and Catherine. He shared songwriting credit on several songs on Hole's 1998 album "Celebrity Skin"; the title track became Corgan's second No. 1 modern rock hit. He also acted as a consultant for Marilyn Manson during the recording of the album "Mechanical Animals". He has produced three soundtracks for the movies "Ransom" (1996), "Stigmata" (1999) and "Spun" (2002) in which he appeared as a doctor.  Corgan appeared at the 1996 Rock and Roll Hall of Fame ceremonies. He inducted one of his biggest musical influences, Pink Floyd. He played acoustic guitar during the ceremony with Pink Floyd, when they performed their song "Wish You Were Here".  In particular, Corgan guided and collaborated with three bands in the 2000s—Breaking Benjamin (during sessions for 2004's "We Are Not Alone"), Taproot (for "Blue-Sky Research", 2005), and Sky Saxon.  In 2010, Corgan claimed co-writing credit (with ex-girlfriend Courtney Love) on at least two of the songs on Hole's final album "Nobody's Daughter" and tried to assert a right of approval before the album could be released. Corgan had helped develop the album during its early stages. The album was released without the writing controversy ever being litigated or publicly resolved.  Corgan appeared as a guest vocalist on the song "Loki Cat" on Jimmy Chamberlin's first solo album, "Life Begins Again", and Chamberlin played drums for the song "DIA" on Corgan's solo debut, where Robert Smith from The Cure teamed up with Corgan to do a cover of the Bee Gees' "To Love Somebody". In 2007, Corgan provided vocals on the Scorpions' song "The Cross", on their album "". In 2010 Corgan featured on Ray Davies' album See My Friends on the album's closer, a mash-up of the Kinks songs "All Day and All of the Night" and "Destroyer". He also contributed his guitar work on "Did You Miss Me" by The Veronicas. Corgan has also collaborated with Tony Iommi, Blindside, David Bowie (singing "All the Young Dudes" with Bowie at Bowie's 50th birthday party), New Order and Marianne Faithfull.

Musical style and influences.

When asked in a 1994 "Rolling Stone" interview about his influences, Corgan replied:  Corgan wrote six articles for "Guitar World" in 1995, and his solos for "Cherub Rock" and "Geek U.S.A." were included on their list of the top guitar solos of all time. AllMusic said "Starla" "proves that Corgan was one of the finest (and most underrated) rock guitarists of the '90s", while "Rolling Stone" called him and his Smashing Pumpkins bandmates "ruthless virtuosos". His solo for "Soma" was No. 24 on "Rolling Stone"'s list of the top guitar solos. He is a fan of Eddie Van Halen and interviewed him in 1996 for "Guitar World". Other guitarists Corgan rates highly include Uli Jon Roth, Tony Iommi, Ritchie Blackmore, Leslie West, Dimebag Darrell and Robin Trower.  His bass playing, which has featured on nearly every Smashing Pumpkins album, was influenced by post-punk figures like Peter Hook and Simon Gallup.  Corgan has praised Radiohead, saying "if they're not the best band in the world, then they're one of the best". He is also a fan of Pantera and appeared briefly in their home video 3 Watch It Go. Other favorites include Depeche Mode, Siouxsie and the Banshees, Rush, Pink Floyd, Led Zeppelin, The Cure, Metallica, Queen, Electric Light Orchestra, Dinosaur Jr., My Bloody Valentine, and Spiritualized. Corgan stated in 1997 that upon hearing the U2 song "New Year's Day", at 16, "[U2] quickly became the most important band in the world to me." Corgan particularly went out of his way to praise Rush in his interview for "", a documentary on the band, where he criticized mainstream reviewers for consciously marginalizing the band and their influence, and highlighted the fact that many of his musical peers were influenced by Rush.  He has listed his artistic influences as William S. Burroughs, Pablo Picasso, Jimi Hendrix, Jack Kerouac, and Philip K. Dick.

Instruments.

Corgan played (during the "Gish"-"Siamese Dream" era) a customized '57 Reissue Fender Stratocaster equipped with three Fender Lace Sensor pickups (the Lace Sensor Blue in the neck position, the Lace Sensor Silver in the middle position, and the Lace Sensor Red at the bridge position). It also has a five-position pickup selector switch which he installed himself. This battered Strat became his number one guitar by default. He owned a '74 Strat that was stolen shortly after "Gish" was completed. Corgan was reunited with this guitar in early 2019.  Corgan also used a wide variety of guitars on "Mellon Collie and the Infinite Sadness". On "Where Boys Fear to Tread", Corgan used a Les Paul Junior Reissue, and on "Tonight Tonight" he used a '72 Gibson ES-335. He is also known to use a '74 Strat which has since been painted baby blue. That guitar was used on the recordings for "Bullet with Butterfly Wings" and also "Muzzle", because the heavier wood gave it the basic Strat sound with a bit more bottom.  During the recording and tour of the album "Zeitgeist", Corgan used a Schecter C-1 EX baritone, finished in black with Tony Iommi signature pickups. Corgan also endorsed Reverend Guitars in his "Zwan" era, most notably playing a Reverend Slingshot.  In 2008 Corgan released to the market his own Fender Stratocaster. This new guitar was made to Corgan's exact specs to create his famous mid-'90s buzzsaw tone; the instrument features three DiMarzio pickups (two custom for this instrument), a string-through hardtail bridge and a satin nitrocellulose lacquer finish. When playing live, he uses both his signature Strats as well as two other Fender Strats, one in red with a white pick guard and one in silver-grey with a black pick guard; a Gibson Tony Iommi signature SG; and his Schecter C-1 (only used on the "Zeitgeist" song "United States").  A video called 'Stompland' on the official Smashing Pumpkins YouTube channel is informative on Corgan's choice of effects pedals. In the video he reveals an extensive collection of pedals used throughout his career with the Smashing Pumpkins. Corgan's tone is often characterized by his use of fuzz pedals, particularly vintage versions of the Electro-Harmonix Big Muff  In 2016 Reverend Guitars released the BC-1 Billy Corgan signature guitar featuring Railhammer Billy Corgan signature pickups.  The Reverend Billy Corgan Signature Terz was launched at the 2018 NAMM show—an electric version of a 19th-century instrument that is played as if the guitar is capoed at the third fret, and tuned G-g standard. Corgan often uses the capo at the third fret and asked for a higher-register guitar.  Corgan is noted for having used Marshall and Diezel amps. He has also used modular preamps based on many different amps in conjunction with Mesa Boogie poweramps. The preamps were built custom built by Salvation Mods.  In August 2017, Corgan sold a large collection of instruments and gear used throughout his career via music gear website Reverb.  Savior")

William Patrick Corgan Jr. (born March 17, 1967) is an American musician, singer, songwriter, and professional wrestling promoter. He is best known as the lead singer, primary songwriter, guitarist, and only permanent member of the rock band the Smashing Pumpkins. He is currently the owner and promoter of the National Wrestling Alliance (NWA) promotion.

William „Billy“ Patrick Corgan (* 17. März 1967 in Chicago, Illinois) ist ein US-amerikanischer Musiker, Musikproduzent, Songschreiber, Lyriker und Bandleader der Alternative-Rock-Band Smashing Pumpkins sowie Wrestling-Unternehmer.


History.

The modern automobile drum brake was first used in a car made by Maybach in 1900, although the principle was only later patented in 1902 by Louis Renault. He used woven asbestos lining for the drum brake lining, as no alternative dissipated heat like the asbestos lining, though Maybach had used a less sophisticated drum brake. In the first drum brakes, levers and rods or cables operated the shoes mechanically. From the mid-1930s, oil pressure in a small wheel cylinder and pistons (as in the picture) operated the brakes, though some vehicles continued with purely mechanical systems for decades. Some designs have two wheel cylinders.  As the shoes in drum brakes wear, brakes required regular manual adjustment until the introduction of self-adjusting drum brakes in the 1950s. Drums are prone to brake fading with repeated use.  In 1953, Jaguar fielded three cars equipped with disc brakes at Le Mans, where they won, in large part due to their superior braking over drum-equipped rivals. This spelled the beginning of the crossover of drum brakes to disc brakes in passenger cars. From the 1960s to the 1980s, disc brakes gradually replaced drum brakes on the front wheels of cars. Now practically all cars use disc brakes on the front wheels, and many use disc brakes on all four wheels.  In the United States, the Jeep CJ-5 (manufactured by AM General) was the final automobile (produced for the United States Postal Service) to use front drum brakes when it was phased out in 1986. However, drum brakes are still often used for handbrakes, as it has proven very difficult to design a disc brake suitable for holding a parked car. Moreover, it is very easy to fit a drum handbrake "inside" a disc brake so that one unit serves as both service brake and handbrake.  Early brake shoes contained asbestos. When working on brake systems of older cars, care must be taken not to inhale any dust present in the brake assembly. The United States Federal Government began to regulate asbestos production, and brake manufacturers had to switch to non-asbestos linings. Owners initially complained of poor braking with the replacements; however, technology eventually advanced to compensate. A majority of daily-driven older vehicles have been fitted with asbestos-free linings. Many other countries also limit the use of asbestos in brakes.

Components.

Drum brake components include the backing plate, brake drum, shoe, wheel cylinder, and various springs and pins.

Backing plate.

The backing plate provides a base for the other components. The back plate also increases the rigidity of whole set-up, supports the housing, and protects it from foreign materials like dust and other road debris. It absorbs the torque from the braking action, and that is why back plate is also called the "Torque Plate". Since all braking operations exert pressure on the backing plate, it must be strong and wear-resistant. Levers for emergency or parking brakes, and automatic brake-shoe adjuster were also added in recent years.

Brake drum.

The brake drum is generally made of a special type of cast iron that is heat-conductive and wear-resistant. It rotates with the wheel and axle. When a driver applies the brakes, the lining pushes radially against the inner surface of the drum, and the ensuing friction slows or stops rotation of the wheel and axle, and thus the vehicle. This friction generates substantial heat.

Wheel cylinder.

One wheel cylinder operates the brake on each wheel. Two pistons operate the shoes, one at each end of the wheel cylinder. The leading shoe (closest to the front of the vehicle) is known as the primary shoe. The trailing shoe is known as the secondary shoe. Hydraulic pressure from the master cylinder acts on the piston cup, pushing the pistons toward the shoes, forcing them against the drum. When the driver releases the brakes, the brake shoe springs restore the shoes to their original (disengaged) position. The parts of the wheel cylinder are shown to the right.

Brake shoe.

Brake shoes are typically made of two pieces of steel welded together. The friction material is either riveted to the lining table or attached with adhesive. The crescent-shaped piece is called the Web and contains holes and slots in different shapes for return springs, hold-down hardware, parking brake linkage and self-adjusting components. All the application force of the wheel cylinder is applied through the web to the lining table and brake lining. The edge of the lining table generally has three “V"-shaped notches or tabs on each side called nibs. The nibs rest against the support pads of the backing plate to which the shoes are installed. Each brake assembly has two shoes, a primary and secondary. The primary shoe is located toward the front of the vehicle and has the lining positioned differently from the secondary shoe. Quite often, the two shoes are interchangeable, so close inspection for any variation is important.  Linings must be resistant to heat and wear and have a high friction coefficient unaffected by fluctuations in temperature and humidity. Materials that make up the brake shoe lining include, friction modifiers (which can include graphite and cashew nut shells), powdered metal such as lead, zinc, brass, aluminium and other metals that resist heat fade, binders, curing agents and fillers such as rubber chips to reduce brake noise.  In the UK two common grades of brake shoe material used to be available. DON 202 was a high friction material that did not require a brake power servo. The disadvantage was that the lining was prone to fading on steep hills. A harder lining, the famous VG95 was produced but this required a brake servo. The other snag was that the parking brake would often fail the annual MOT test unless the high friction linings were installed just for the test.

In operation.

Normal braking.

When the brakes are applied, brake fluid is forced under pressure from the master cylinder into the wheel cylinder, which in turn pushes the brake shoes into contact with the machined surface on the inside of the drum. This rubbing action reduces the rotation of the brake drum, which is coupled to the wheel. Hence the speed of the vehicle is reduced. When the pressure is released, return springs pull the shoes back to their rest position.

Automatic self-adjustment.

As the brake linings wear, the shoes must travel a greater distance to reach the drum. In systems fitted with automatic adjusters, when the distance reaches a certain point, a self-adjusting mechanism automatically reacts by adjusting the rest position of the shoes so that they are closer to the drum. Here, the adjusting lever rocks enough to advance the adjuster gear by one tooth. The adjuster has threads on it, like a bolt, so that it unscrews a little bit when it turns, lengthening to fill in the gap. When the brake shoes wear a little more, the adjuster can advance again, so it always keeps the shoes close to the drum. Typically the adjusters only operate when the vehicle is going in reverse and the brakes are engaged.  On vehicles without automatic adjusters, it is required to periodically manually adjust the brakes to take up any excess gap between the shoes and the drum.

Parking/emergency brake.

The parking (or emergency) brake system controls the brakes through a series of steel cables that are connected to either a hand lever or a foot pedal. The idea is that the system is fully mechanical and completely bypasses the hydraulic system so that the vehicle can be brought to a stop even if there is a total brake failure. Here the cable pulls on a lever mounted in the brake and is directly connected to the brake shoes. This has the effect of bypassing the wheel cylinder and controlling the brakes directly.

Self-applying characteristic.

Drum brakes have a natural "self-applying" characteristic, better known as "self-energizing." The rotation of the drum can drag either one or both of the shoes into the friction surface, causing the brakes to bite harder, which increases the force holding them together. This increases the stopping power without any additional effort being expended by the driver, but it does make it harder for the driver to modulate the brake's sensitivity. It also makes the brake more sensitive to brake fade, as a decrease in brake friction also reduces the amount of brake assist.  Disc brakes exhibit no self-applying effect because the hydraulic pressure acting on the pads is perpendicular to the direction of rotation of the disc. Disc brake systems usually have servo assistance ("Brake Booster") to lessen the driver's pedal effort, but some disc braked cars (notably race cars) and smaller brakes for motorcycles, etc., do not need to use servos.

Drum brake designs.

Drum brakes are typically described as either leading/trailing (also called "single leading") or twin leading.  Rear drum brakes are typically of a leading/trailing design (for non-servo systems), or primary/secondary (for duo servo systems), the shoes being moved by a single double-acting hydraulic cylinder and hinged at the same point. In this design, one of the brake shoes always experiences the self-applying effect, irrespective of whether the vehicle is moving forwards or backwards. This is particularly useful on the rear brakes, where the parking brake (handbrake or footbrake) must exert enough force to stop the vehicle from traveling backwards and hold it on a slope. Provided the contact area of the brake shoes is large enough, which isn't always the case, the self-applying effect can securely hold a vehicle when the weight is transferred to the rear brakes due to the incline of a slope or the reverse direction of motion. A further advantage of using a single hydraulic cylinder on the rear is that the opposite pivot may be made in the form of a double-lobed cam that is rotated by the action of the parking brake system.  Front drum brakes may be of either design in practice, but the twin leading design is more effective. This design uses two actuating cylinders arranged so that both shoes use the self-applying characteristic when the vehicle is moving forwards. The brake shoes pivot at opposite points to each other. This gives the maximum possible braking when moving forwards, but is not so effective when the vehicle is traveling in reverse.  The optimum arrangement of twin leading front brakes with leading/trailing brakes on the rear allows more braking force at the front of the vehicle when it is moving forwards, with less at the rear. This helps prevent the rear wheels from locking up, but still provides adequate braking at the rear. The brake drum itself is frequently made of cast iron, though some vehicles have used aluminum drums, particularly for front-wheel applications. Aluminum conducts heat better than cast iron, which improves heat dissipation and reduces fade. Aluminum drums are also lighter than iron drums, which reduces unsprung weight. Because aluminum wears more easily than iron, aluminum drums frequently have an iron or steel liner on the inner surface of the drum, bonded or riveted to the aluminum outer shell.

Advantages.

Drum brakes are used in most heavy duty trucks, some medium and light duty trucks, and few cars, dirt bikes, and ATVs. Drum brakes are often applied to the rear wheels since most of the stopping force is generated by the front brakes of the vehicle and therefore the heat generated in the rear is significantly less. Drum brakes allow simple incorporation of a parking brake.  Drum brakes are also occasionally fitted as the parking (and emergency) brake even when the rear wheels use disc brakes as the main brakes. Many rear disc braking systems use a parking brake in which the piston in the caliper is actuated by a cam or screw. This compresses the pads against the rotor. However, this type of system becomes "much" more complicated when the rear disc brakes use fixed, multi-piston calipers. In this situation, a small drum is usually fitted within or as part of the brake disc. This type of brake is also known as a banksia brake.  In hybrid vehicle applications, wear on braking systems is greatly reduced by energy recovering motor-generators (see regenerative braking), so some hybrid vehicles such as the GMC Yukon Hybrid and Toyota Prius (except the third generation) use drum brakes at the rear wheels.  Disc brakes rely on pliability of caliper seals and slight runout to release pads, leading to drag, fuel mileage loss, and disc scoring. Drum brake return springs give more positive action and, adjusted correctly, often have less drag when released. It is however possible to design special seals that retract the piston on a disc brake.  Drum brakes emit less particulate matter (PM) than disc brakes, as the wear-particles are mostly sealed in. They are not better in this regard than frictionless brakes though.  Certain heavier duty drum brake systems compensate for load when determining wheel cylinder pressure; a feature rare when discs are employed (Hydropneumatic suspension systems as employed on Citroën vehicles adjust brake pressure depending on load regardless of if drum or discs are used). One such vehicle is the Jeep Comanche. The Comanche can automatically send more pressure to the rear drums depending on the size of the load. Most other brands have used load sensing valves in the hydraulics to the rear axle for decades.  Due to the fact that a drum brake's friction contact area is at the circumference of the brake, a drum brake can provide more braking force than an equal diameter disc brake. The increased friction contact area of drum brake shoes on the drum allows drum brake shoes to last longer than disc brake pads used in a brake system of similar dimensions and braking force. Drum brakes retain heat and are more complex than disc brakes but are often the more economical and powerful brake type to use in rear brake applications due to the low heat generation of rear brakes, a drum brake's self-applying nature, larger friction surface contact area, and long life wear characteristics (%life used/kW of braking power).  To list advantages of drum brakes:

As a driveshaft parking/emergency brake.

Drum brakes have also been built onto the transmission's driveshaft as parking brakes (e.g., Chryslers through 1962). This provides the advantage that it is completely independent of the service brakes—but suffers a severe disadvantage in that, when used with a bumper jack (common in that era) on the rear, and without proper wheel blocks, the differential's action can allow the vehicle to roll off the jack.  Land Rover have used a drum brake on the gearbox output shaft for over fifty years. The advantage is that all four wheels can be braked with the parking brake.

Disadvantages.

Drum brakes, like most other brakes, convert kinetic energy into heat by friction. This heat should dissipate into the surrounding air, but can just as easily transfer to other braking system components. Brake drums must be large to cope with the massive forces involved, and must be able to absorb and dissipate a lot of heat. Heat transfer to air can be aided by incorporating cooling fins onto the drum. However, excessive heating can occur due to heavy or repeated braking, which can cause the drum to distort, leading to vibration under braking.  The other consequence of overheating is brake fade. This is due to one of several processes or more usually an accumulation of all of them.  Brake fade is not always due to overheating. Water between the friction surfaces and the drum can act as a lubricant and reduce braking efficiency. The water tends to stay until heated sufficiently to vaporize, at which point braking efficiency returns. All friction braking systems have a maximum theoretical rate of energy conversion. Once that rate is reached, applying greater pedal pressure doesn't change it—in fact, the effects mentioned can substantially reduce it. Ultimately, this is what brake fade is, regardless of the mechanisms of its causes. Disc brakes are not immune to any of these processes, but they deal with heat and water more effectively than drums.  Drum brakes can be grabby if the drum surface gets light rust or if the brake is cold and damp, giving the pad material greater friction. Grabbing can be so severe that the tires skid and continue to skid even when the pedal is released. Grab is the opposite of fade: when the pad friction goes up, the self-assisting nature of the brakes causes application force to go up. If the pad friction and self-amplification are high enough, the brake stay engaged due to self-application, even when the external application force is released.  While disc brake rotors can be machined to clean the friction surface (i.e., 'turning'), the same generally cannot be done with brake drums. Machining the friction surface of a brake drum increases the diameter, which might require oversized shoes to maintain proper contact with the drum. However, since oversized shoes are generally unavailable for most applications, worn or damaged drums generally must be replaced.  It is quite simple to machine brake drums if one has a slow running lathe (one rule of thumb is that cast iron should not be machined faster than fifty feet per minute). Usually it is only necessary to machine away the ridge that forms that makes brake drum removal difficult. If the ridge is left on big trouble can occur later especially if the brakes are self-adjusting. In bad cases this ridge can make the brake drum captive. Most drum brake designs provide a way to externally release the self-adjusting mechanism in order to ease drum removal and service.  Another disadvantage of drum brakes is their relative complexity. A person must have a general understanding of how drum brakes work and take simple steps to ensure the brakes are reassembled correctly when doing work on drum brakes. And, as a result of this increased complexity (compared to disc brakes), maintenance of drum brakes is generally more time-consuming. Also, the greater number of parts results in a greater number of failure modes compared to disc brakes. Springs can break from fatigue if not replaced along with worn brake shoes. And the drum and shoes can become damaged from scoring if various components (such as broken springs or self-adjusters) break and become loose inside the drum.  Catastrophic failure of hardware such as springs and adjusters can also cause unintended brake application or even wheel lockup. If springs break, the shoes will be free to fall against the rotating drum, essentially causing the brakes to be applied. Because of the self-energizing qualities of drum brakes, the unrestrained shoes can even potentially cause the brakes to grab to the point of locking up the wheel. Also, broken pieces of springs and other hardware (like adjusters) can become lodged between the shoes and drum, resulting in unintended application of the brakes (and, as stated above, damage to brake components). For these reasons, brake hardware (such as springs and clips) should always be replaced with brake shoes.  Also, drum brakes do not apply immediately when the wheel cylinders are pressurized, because the force of the return springs must be overcome before the shoes start to move towards the drum. This means that the very common hybrid disc/drum systems only brake with the discs on light pedal pressure unless extra hardware is added. In practice, a metering valve prevents hydraulic pressure from reaching the front calipers until pressure rises enough to overcome the return springs in the drum brakes. If the metering valve were left out, the vehicle would stop only with the front discs until return spring pressure on the rear shoes were overcome.

Safety.

When asbestos was common in drum brakes, there was a danger workers repairing or replacing them would breathe asbestos fibers, which can cause mesothelioma. Asbestos fibers would break off or become separated over time and with the high temperatures induced by braking. Wet brushes and aerosol sprays were commonly used to reduce dust. Safety regulators sometimes recommended using vacuum hoses to suck away the dust, or enclosures with interior lighting and space to use tools inside them, but these were rare and cumbersome. Distinctive shoes designed to protect against asbestos were also recommended. There is evidence that auto mechanics had disproportionate levels of mesothelioma.  Those who do maintenance work on brakes can also be exposed to the solvents 1,1,1-trichloroethane and 2-butoxyethanol (a main ingredient in Greasoff No. 19). Exposure to these solvents can cause irritation, including to the eyes and mucous membranes. Exposure to 1-1-1-trichloroethane vapors can cause central nervous system damage, dizziness, incoordination, drowsiness, and increased reaction time.

Re-arcing.

Before 1984, it was common to re-arc brake shoes to match the arc within brake drums. This practice, however, was controversial, as it removed friction material from the brakes and reduced the life of the shoes as well as created hazardous asbestos dust. Current design theory is to use shoes for the proper diameter drum, and to simply replace the brake drum when necessary, rather than re-arcing shoes.

Use in music.

Brake drums are used in modern concert and film music to provide a non-pitched metal sound similar to an anvil. Some are more resonant than others. To produce the clearest sound, percussionists hang the drum with nylon cord or place it on foam. Other methods include mounting the brake drum on a snare drum stand. Either way, the percussionist strikes the brake drum with hammers or sticks of various weight.

A drum brake is a brake that uses friction caused by a set of shoes or pads that press outward against a rotating cylinder-shaped part called a brake drum.

Trommelbremsen sind Reibungsbremsen, bei denen Bremsbeläge auf eine zylindrische Fläche (die Trommel) wirken. Beim Betätigen der Bremse wird der Bremsbelag üblicherweise von innen gegen die umlaufende Trommel gedrückt. In Kraftfahrzeugen wurden Trommelbremsen von Scheibenbremsen abgelöst. Bei leistungsschwächeren Pkw werden sie noch an der Hinterachse eingesetzt; bei schweren Nutzfahrzeugen sowie Anhängern ist die Trommelbremse immer noch Stand der Technik.


Description.

Azhdarchids are characterized by their long legs and extremely long necks, made up of elongated neck vertebrae which are round in cross section. Most species of azhdarchids are still known mainly from their distinctive neck bones and not much else. The few azhdarchids that are known from reasonably good skeletons include "Zhejiangopterus" and "Quetzalcoatlus". Azhdarchids are also distinguished by their relatively large heads and long, spear-like jaws. There are two major types of azhdarchid morphologies: the "blunt-beaked" forms with shorter and deeper bills and the "slender-beaked" forms with longer and thinner jaws.  It had been suggested azhdarchids were skimmers, but further research has cast doubt on this idea, demonstrating that azhdarchids lacked the necessary adaptations for a skim-feeding lifestyle, and that they may have led a more terrestrial existence similar to modern storks and ground hornbills. Most large azhdarchids probably fed on small prey, including hatchling and small dinosaurs; in an unusual modification of the azhdarchid bauplan, the unusually robust "Hatzegopteryx" may have tackled larger prey as the apex predator in its ecosystem. In another departure from typical azhdarchid lifestyles, the jaw of "Alanqa" may possibly be an adaptation to crushing shellfish and other hard foodstuffs.  Azhdarchids are generally medium- to large-sized pterosaurs, with the largest achieving wingspans of, but several small-sized species have recently been discovered. Another azhdarchid that is currently unnamed, recently discovered in Transylvania, may be the largest representative of the family thus far discovered. This unnamed specimen (nicknamed "Dracula" by paleontologists), currently on display in the Altmühltal Dinosaur Museum in Bavaria is estimated to have a wingspan of, although similarities to the contemporary azhdarchid "Hatzegopteryx" have also been noted.

Systematics.

Azhdarchids were originally classified as close relatives of "Pteranodon" due to their long, toothless beaks. Others have suggested they were more closely related to the toothy ctenochasmatids (which include filter-feeders like "Ctenochasma" and "Pterodaustro"). Currently it is widely agreed that azhdarchids were closely related to pterosaurs such as "Tupuxuara" and "Tapejara".

Taxonomy.

Classification after Unwin 2006, except where noted.

Azhdarchidae (from the Persian word "azhdar" (), a dragon-like creature in Persian mythology) is a family of pterosaurs known primarily from the late Cretaceous Period, though an isolated vertebra apparently from an azhdarchid is known from the early Cretaceous as well (late Berriasian age, about 140 million years ago). Azhdarchids included some of the largest-known flying animals of all time, but members no larger than a cat have also been found. Originally considered a sub-family of Pteranodontidae, Nesov (1984) named the azhdarchinae to include the pterosaurs "Azhdarcho", "Quetzalcoatlus", and "Titanopteryx" (now known as "Arambourgiania"). They were among the last known surviving members of the pterosaurs, and were a rather successful group with a worldwide distribution. By the time of the end-Cretaceous mass extinction, most pterosaur families except for the Azhdarchidae disappear from the fossil record, but recent studies indicate a wealth in pterosaurian faunas, including pteranodontids, nyctosaurids, tapejarids and several indeterminate forms. Some taxa like "Navajodactylus", "Bakonydraco" and "Montanazhdarcho" were moved from Azhdarchidae to other clades.

Die Azhdarchidae sind eine Gruppe der ausgestorbenen Flugsaurier (Pterosauria). Die weltweit verbreitete Gruppe ist seit der frühen Kreidezeit nachgewiesen, erreicht ihre größte Vielfalt jedoch in der späten Kreidezeit und starb erst am Ende dieser Epoche zusammen mit den Dinosauriern aus. Azhdarchiden schließen die größten flugfähigen Tiere der Erdgeschichte mit ein. Die größten Vertreter zeigten Flügelspannweiten von schätzungsweise 10 bis 11 Meter und erreichten mit Standhöhen von über fünf Meter die Höhe heutiger Giraffen. Azhdarchiden zählen zu den für den Laien am leichtesten zu erkennenden Flugsauriergruppen – charakteristische Merkmale schließen die langen, unbezahnten Kiefer, den langen Hals, die proportional kurzen Flügel sowie die langen Hinterbeine mit ein. Zur Lebensweise dieser Tiere wurde eine Vielzahl von Hypothesen postuliert; die jüngste Studie kommt zu dem Schluss, dass Azhdarchiden wie heutige Schreitvögel am Boden diversen Beutetieren nachstellten. Namensgebend für die zu den Kurzschwanzflugsauriern (Pterodactyloidea) zählenden Azhdarchiden ist die Gattung "Azhdarcho", deren Bezeichnung auf "Aždahā", den Namen für Drache aus dem Persischen zurückgeht.


Description.

Elasmobranchii is one of the two subclasses of cartilaginous fish in the class Chondrichthyes, the other being Holocephali (chimaeras).  Members of the elasmobranchii subclass have no swim bladders, five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins, and small placoid scales. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper.  Extant elasmobranchs exhibit several archetypal jaw suspensions: amphistyly, orbitostyly, hyostyly, and euhyostyly. In amphistyly, the palatoquadrate has a postorbital articulation with the chondrocranium from which ligaments primarily suspend it anteriorly. The hyoid articulates with the mandibular arch posteriorly, but it appears to provide little support to the upper and lower jaws. In orbitostyly, the orbital process hinges with the orbital wall and the hyoid provides the majority of suspensory support.  In contrast, hyostyly involves an ethmoid articulation between the upper jaw and the cranium, while the hyoid most likely provides vastly more jaw support compared to the anterior ligaments. Finally, in euhyostyly, also known as true hyostyly, the mandibular cartilages lack a ligamentous connection to the cranium. Instead, the hyomandibular cartilages provide the only means of jaw support, while the ceratohyal and basihyal elements articulate with the lower jaw, but are disconnected from the rest of the hyoid. The eyes have a tapetum lucidum. The inner margin of each pelvic fin in the male fish is grooved to constitute a clasper for the transmission of sperm. These fish are widely distributed in tropical and temperate waters.  Many fish maintain buoyancy with swim bladders. However elasmobranchs lack swim bladders, and maintain buoyancy instead with large livers that are full of oil. This stored oil may also function as a nutrient when food is scarce. Deep sea sharks are usually targeted for their oil, because the livers of these species can weigh up to 20% of their total weight.

Evolution.

Fossilised shark teeth are known from the early Devonian, around 400 million years ago. During the following Carboniferous period, the sharks underwent a period of diversification, with many new forms evolving. Many of these became extinct during the Permian, but the remaining sharks underwent a second burst of adaptive radiation during the Jurassic, around which time the skates and rays first appeared. Many surviving orders of elasmobranch date back to the Cretaceous, or earlier.

Habitats.

Elasmobranchs are mostly a marine taxon, but we know several species that live in freshwater environment (approximately 60 species which represent only 5% of the 1154 described species). They can be divided into two groups.  The euryhaline elasmobranchs, which are marine species that may survive and reproduce in freshwater environment, and the obligated freshwater elasmobranchs. The second group contains elasmobranchs that only lives in freshwater environment their entire life. This group contains only one clade: the subfamily "Potamotrygoninae". This clade is endemic to one specific region (which means that they can only be seen in those regions): tropical, subtropical water and wetland of South America.  Recent researches in Paraná river have shown that obligated freshwater elasmobranchs were more susceptible to anthropogenic threats as overfishing and destruction of habitats due to the very small place they live in compared to the marine species.  New research has highlighted the importance of coastal wetlands, like mangroves and seagrasses, as habitats for many species of elasmobranch

Taxonomy.

Compagno's 2005 "Sharks of the World" arranges the class as follows:  Recent molecular studies suggest the Batoidea are not derived selachians as previously thought. Instead, skates and rays are a monophyletic superorder within Elasmobranchii that shares a common ancestor with the selachians.

Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including the sharks (superorder Selachii) and the rays, skates, and sawfish (superorder Batoidea). Members of this subclass are characterised by having four (tawny nurse sharks have 4 pairs of gills) to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.

Die Plattenkiemer (Elasmobranchii, Synonym: Neoselachii), genannt auch Hai- und Rochenartige, sind eine Teilklasse der Knorpelfische (Chondrichthyes). Zu ihnen gehören die modernen Haie (Selachii) und Rochen (Batomorphi) mit etwa 1150 rezenten Arten. Etwa 30 Arten leben vor allem im Süßwasser, der Rest im Meer.