Academic literature on the topic 'Pawl clutch'
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Journal articles on the topic "Pawl clutch"
1
Roach, Gregory M., and Larry L. Howell. "Evaluation and Comparison of Alternative Compliant Overrunning Clutch Designs." Journal of Mechanical Design 124, no. 3 (August 6, 2002): 485–91. http://dx.doi.org/10.1115/1.1480414.
Full textAbstract:
Compliance criteria are used to evaluate the general class of over-running clutches to determine which type is best suited to benefit from compliance. The criteria used in the evaluation include the presence and angle of rotation of revolute joints, the possibility for part count reduction, the presence of springs, possible reduction in weight, and the method of clutch engagement. Sprag, spring, roller or ball, and ratchet and pawl clutch types were evaluated, and the ratchet and pawl type of over-running clutch was demonstrated to be the most promising. Within this type of over-running clutch, different designs incorporating bending, tension, and compression loading of the pawls were explored to determine the best method for loading the pawls. The clutches were compared using the maximum output torque. It was determined that the clutch incorporating rigid pawls loaded in compression produced the largest output torque. The maximum output torque for this clutch was measured at 65.6 N-m.
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Zhou, Guo Qing, Ru Wang Yuan, and Xiu Ming Jiang. "Study on Design of Ratchet-Pawl Clutch in Winder." Applied Mechanics and Materials 215-216 (November 2012): 263–69. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.263.
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Basing on an analysis on the motion cycle switching of yarn splicing device and tube changing device of an automatic twisting winder using ratchet-pawl clutch, this paper studies the self-locking conditions of the ratchet-pawl clutch, the rotation angle and revolution angle for separation of the pawl, the pawl escapement and the pawl disk locating device, gets the calculation method and design formulas for functional parameters of the ratchet-pawl clutch, and finds out the conditions for whole circle rotation and precise locating of the pawl disk.
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Unciuleac, Mihaela-Carmen, Aviv Meir, Chaoyou Xue, Garrett M. Warren, Eric C. Greene, and Stewart Shuman. "Clutch mechanism of chemomechanical coupling in a DNA resecting motor nuclease." Proceedings of the National Academy of Sciences 118, no. 11 (March 8, 2021): e2023955118. http://dx.doi.org/10.1073/pnas.2023955118.
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Mycobacterial AdnAB is a heterodimeric helicase–nuclease that initiates homologous recombination by resecting DNA double-strand breaks (DSBs). The N-terminal motor domain of the AdnB subunit hydrolyzes ATP to drive rapid and processive 3′ to 5′ translocation of AdnAB on the tracking DNA strand. ATP hydrolysis is mechanically productive when oscillating protein domain motions synchronized with the ATPase cycle propel the DNA tracking strand forward by a single-nucleotide step, in what is thought to entail a pawl-and-ratchet–like fashion. By gauging the effects of alanine mutations of the 16 amino acids at the AdnB–DNA interface on DNA-dependent ATP hydrolysis, DNA translocation, and DSB resection in ensemble and single-molecule assays, we gained key insights into which DNA contacts couple ATP hydrolysis to motor activity. The results implicate AdnB Trp325, which intercalates into the tracking strand and stacks on a nucleobase, as the singular essential constituent of the ratchet pawl, without which ATP hydrolysis on ssDNA is mechanically futile. Loss of Thr663 and Thr118 contacts with tracking strand phosphates and of His665 with a nucleobase drastically slows the AdnAB motor during DSB resection. Our findings for AdnAB prompt us to analogize its mechanism to that of an automobile clutch.
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Wang, Yong Mei, and Xi Gui Wang. "Analysis and Optimization of Embedded Flexible Clutch Brake Wheel and Brake Claw Structure." Key Engineering Materials 579-580 (September 2013): 542–47. http://dx.doi.org/10.4028/www.scientific.net/kem.579-580.542.
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Based on the embedded flexible clutch mechanism as the breakthrough point, using ADAMS dynamic analysis software and ANSYS simulation analysis software, established the analysis model, the peak impact force between the different conditions of brake wheel and brake claw was obtained, the brake wheel and the brake pawl two allowable angular speed difference. At the same time to brake wheel and brake claw structure impact resistance ability as optimization objective, the different structural forms of brake wheel and brake claw structure peak impact in different conditions and the brake wheel and brake claw two permissible angular speed difference is analyzed and calculated.
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HOU, ShengLiang, Lei HOU, and TingWei LIANG. "Dynamic simulation analysis of a ratchet pawl clutch for a certain type of aviation." SCIENTIA SINICA Technologica 48, no. 9 (July 5, 2018): 999–1011. http://dx.doi.org/10.1360/n092018-00015.
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Hunt, George L., Zoe A. Eppley, and David C. Schneider. "Reproductive Performance of Seabirds: The Importance of Population and Colony Size." Auk 103, no. 2 (April 1, 1986): 306–17. http://dx.doi.org/10.1093/auk/103.2.306.
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Abstract We compared reproductive performance of five species of seabirds at two colonies, St. George Island (2.5 million birds) and St. Paul Island (250,000 birds), in the southeastern Bering Sea. All species had lower chick growth rates at the larger colony, and the differences were statistically significant in four species. Fledge weights of Common Murres (Uria aalge) on St. George Island were 84-88% of those on St. Paul. Average fledge weights of Thick-billed Murres (Uria lomvia) on St. George were only 74% of those for chicks from St. Paul. We found no significant differences in clutch size or breeding success between populations breeding at the two colonies. For three species, Black-legged Kittiwakes (Rissa tridactyla), Common Murres, and Thick-billed Murres, we extended our analysis to include published data from other colonies. We examined breeding performance as a function of colony size, population size (suggestive of intraspecific competition), and "effective colony size," the sum of the populations of species with considerable dietary overlap (suggestive of interspecific competition for food). We found consistently negative relationships between population size and several measures of breeding performance (clutch size, growth rate, fledge weight, and breeding success). In addition to the lower breeding success at colonies that support large populations, chicks from these colonies may be subject to higher postfledging mortality because of fledging at lower weights.
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Zlotnikova, Tamara V., Tatyana A. Geld, and Nadezhda K. Dzingel. "The state of Recurvirostra avosetta Linnaeus, 1758 and Larus ichthyaetus Pallas, 1773 (Aves, Charadriiformes) populations of the Tryochozyorki tract (South Minusinsk basin) in 2020." Samara Journal of Science 9, no. 3 (November 20, 2020): 62–66. http://dx.doi.org/10.17816/snv202093111.
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This paper presents the results of observations on the state of two bird species populations listed in the Red Book of the Russian Federation Recurvirostra avosetta L., Larus ichthyaetus Pall. The populations of these species in the State Natural Reserve Tryochozyorki Tract have been studied by the authors for 8 years. The wetland is a key ornithological area of international importance. The paper presents information obtained in 2020, which has been compared with the information received in 20132018 which was published. For R. avosetta L. the maximum number of breeding pairs (127) and the maximum value of the average clutch size (3,6) were noted for the entire observation period. The reproduction of R. avosetta L. started earlier than in previous years. For L. ichthyaetus L. a relatively high number (no less than 280300 pairs) and also the maximum value of the clutch size (3,0) were noted, the breeding time of the species turned out to be typical for this territory. The analysis showed a favorable state of the populations of these species. The previously stated assumption about the relationship of the studied indicators of the nesting biology of these species with the level of water content of the territory was further confirmed.
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Venkatesh, G. "Sustainable Development Goals – Quo Vadis, Cities of the World?" Problemy Ekorozwoju 16, no. 1 (January 1, 2021): 171–79. http://dx.doi.org/10.35784/pe.2021.1.18.
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The United Nations unveiled a set of 17 Sustainable Development Goals (SDGs) in September 2015, with 169 targets and a little over 230 indicators. This was a sequel to the Millennium Development Goals whose remit ended in 2015. Challenges lie ahead for governments around the world – national, provincial and municipal – to adapt the targets and indicators to effect a meaningful transition towards sustainable development by 2030. Cities are where the battle for sustainable development will be won or lost – they contribute 80% of the global GDP, and account for 70% each of global energy consumption and greenhouse gas emissions. With over two-thirds of the global population likely to live in cities by 2060, this is more than a cliché. A clutch of sustainable cities makes a sustainable province; a clutch of sustainable provinces makes a sustainable country, and it follows that several sustainable countries learning and sharing and helping other countries, will make for a sustainable world in the 21st century and further on into the future. While moving forward, trade-offs and complementarities must not be forgotten. Often, there are serendipitous benefits when complementarities which exist are not factored in, but the trade-offs if forgotten may end up robbing Peter to pay Paul. Despite the interregnum brought about by the Corona Virus pandemic in 2020, the world will be getting up, dusting itself clean and moving ahead in the next decade towards the SDGs set for year-2030.
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Wu, Yi-Chang, and Zi-Heng Sun. "Design and Analysis of a Novel Speed-Changing Wheel Hub with an Integrated Electric Motor for Electric Bicycles." Mathematical Problems in Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/369504.
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The aim of this paper is to present an innovative electromechanical device which integrates a brushless DC (BLDC) hub motor with a speed-changing wheel hub stored on the rear wheel of an electric bicycle. It combines a power source and a speed-changing mechanism to simultaneously provide functions of power generation and transmission for electric bicycles. As part of the proposed integrated device, the wheel hub consists of a basic planetary gear train providing three forward speeds including a low-speed gear, a direct drive, and a high-speed gear. Each gear is manually controlled by the shift control sleeve to selectively engage or disengage four pawl-and-ratchet clutches based on its clutching sequence table. The number of gear teeth of each gear element of the wheel hub is synthesized. The BLDC hub motor is an exterior-rotor-type permanent-magnet synchronous motor. Two-dimensional finite-element analysis (FEA) software is employed to facilitate the motor design and performance analysis. An analysis of the power transmission path at each gear is provided to verify the validity of the proposed design. The results of this work are beneficial to the embodiment, design, and development of novel electromechanical devices for the power and transmission systems of electric bicycles.
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Danciu, Liliana. "Deux mythes et le sauvetage d’un philosophe-chaman [Two myths and the salvation of a philosopher-shaman]." Trictrac 10 (May 21, 2018). http://dx.doi.org/10.25159/1996-7330/2423.
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The Forbidden Forest by Mircea Eliade is a “total novel,” whose complexity is evident on every page through the variety of suggestions, metaphors and symbols, of intertextual and mythological references. In this study, I will mostly discuss the penultimate chapter of this novel where the death of Biriș, the rational and sceptical philosopher, at the beginning a follower of the philosophy of Kierkegaard, is presented. In this troubling episode, I identified the presence of two myths whose unconscious actor this rational spirit currently anchored in history became. The myth—an exemplary story about foundation—seeks his Chosen One and finds him in the opposite of an intellectual, an “unbeliever,” just as Jesus chose his most bitter enemy, Paul of Tarsus, to become his faithful apostle. But the gnostic and religious philosopher also needs to believe in self-salvation from the clutches of the demon of fear and cowardice, and impending death, surrounded by friend-interrogators (Mihai Duma), by a compassionate executioner (Bîrsan), and demonic monks (Bursuc). The healing function of the story is lost in this world of suspicion, where Biriș is surrounded by masks, which disguise their true role. The myth of the sacrifice of Christ acquires a double saving power, because Biriș saves himself and redeems his torturers, too. By converting nocturnal stories into a sacred ritual of story, the destiny of Scheherazade, the heroine of One Thousand and One Nights, is saved from the banality of a simple literary character, because “the story in the story” provokes the human being to descend into the abyss and to live by the symbol. In the company of his interrogators—human aspects of demons—the frightened philosopher becomes the image of a Thracian Orpheus, trying in vain to “tame” the human beasts by his wise Logos. By the Logos, Biriș fails to rescue his torturers and himself from their own bestiality, but at the level of his “trance-conscious”—where Eliade speaks in his scientific work—he mystically lives a symbolic and mysterious superposition between the stages of the sacrifice of the shepherd in “Miorița” and those of the sacrifice of Christ. This intelligent, subtle and erudite intellectual lives deeply rooted in history with the consciousness of the presence of death in all intimate structures of life, a mentality specific to Western conception. In the last moments of his life, Biriș is converted to the sacred mystery of the Great Passing. Homo sapiens becomes Homo religiosus, the mysterious veil of Maya rises and the exit of the labyrinth is a certainty. The two myths which I take into account are the Orphic myth about the healing word and the mixture of the mioritic and the Christ myth of salvation through sacrifice.
Dissertations / Theses on the topic "Pawl clutch"
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Roach, Gregory Mark. "An Investigation of Compliant Over-running Ratchet and Pawl Clutches." BYU ScholarsArchive, 2003. https://scholarsarchive.byu.edu/etd/55.
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This thesis proposes that compliant mechanism theory can be used to design over-running ratchet and pawl clutches with reduced part count, lower assembly and manufacturing time while maintaining functionality. An extension of the theory to the micro regime is also briefly addressed. The results of the research show that the ratchet and pawl type of over-running clutch is a good choice for the use of compliance, and the clutch pawls should be loaded in compression to get the largest amount of output torque. It was found that com-pliant mechanism theory can be used to design ratchet and pawl clutches with fewer parts and lower manufacturing and assembly costs, and that these clutches perform comparable to traditional rigid-body ratchet and pawl clutches. Compliant ratchet and pawl clutches can replace traditional rigid-body clutches in some applications and now make it possible to be used in applications where it was once not economically feasible to use a over-running clutch. It was also found that these clutches function at the micro level.
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Roach, Gregory M. "An investigation of compliant over-running ratchet and pawl clutches /." Diss., CLICK HERE for online access, 1998. http://contentdm.lib.byu.edu/ETD/image/etd171.pdf.
Full textConference papers on the topic "Pawl clutch"
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Roach, Gregory M., Scott M. Lyon, and Larry L. Howell. "A Compliant, Over-Running Ratchet and Pawl Clutch With Centrifugal Throw-Out." In ASME 1998 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/detc98/mech-5819.
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Abstract A new compliant, over-running ratchet and pawl clutch with centrifugal throw-out has been developed that drastically reduces the overall part count as compared to traditional ratchet and pawl clutches. Part count for the pawl hub assembly was virtually eliminated by making the hub a single compliant mechanism. This results in large savings in manufacturing, assembly and maintenance costs. Peak torque output for a polypropylene clutch was measured at over 66.2 N-m with an over-running torque measured at < 0.01 N-m. A mathematical model has been developed to predict the rotational speed at which the pawls disengage from the ratchet when free-wheeling. This model was verified experimentally to be accurate within 5.2%. This clutch also demonstrates the advantage of compliant mechanisms to reduce assembly and manufacturing costs.
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Roach, Gregory M., and Larry L. Howell. "Evaluation and Comparison of Alternative Compliant Over-Running Clutch Designs." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/dac-8619.
Full textAbstract:
Abstract Compliance criteria is used to evaluate the general class of over-running clutches to determine which type is best suited to benefit from compliance. The criteria used in the evaluation include the presence and amount of revolution of revolute joints, the possibility for part count reduction, the presence of springs, possible reduction in weight, and the method of clutch engagement. The ratchet and pawl type of over-running clutch was shown to be the most promising. Within this type of over-running clutch, different designs incorporating bending, tension, and compression loading of the pawls were explored to determine the best method for loading the pawls. The clutches were compared using a ratio of the maximum output torque to over-running torque. It was determined that the clutch incorporating rigid pawls loaded in compression produced the largest ratio of output torque to over-running torque. The maximum output torque for this clutch was measured at 65.6 N-m and the over-running torque was measured at 0.011 N-m yielding a ratio of 5964.
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Zobott, Keith D., and Darrel W. Burch. "Full Range Pawl and Ratchet Clutch." In Aerospace Technology Conference and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1992. http://dx.doi.org/10.4271/921946.
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Bronson, Henry D., and Rahuljit Pal. "Human-Hybrid Powered Vehicle (H2PV) Using an Oscillating Drive." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11419.
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For more than a century, bicycle designs have used single chain drive transmissions in the belief that no other option exists. An alternative to a chain driven system is an endless belt transmission system using all three distinct belt forms; flat, V, and toothed. In the described transmission the belt acts as a combination flat and V-belt on the drive pulley, and like a timing belt on the driven pulley. Uniquely, the belt teeth have an asymmetric, pawl like tooth profile. This permits safe operation in conditions when the driven pulley circumference is already moving faster than the drive belt teeth, a common occurrence during bicycle or scooter coasting. The material memory of the elastomeric belt acts to bias the drive to disengagement, yet the belt and drive pulley are light. Combined with carefully positioned back idlers, the mere initiation of a power stroke quickly engages the transmission automatically. One major application described here is a reciprocating drive actuated with natural leg action that is easily augmented with power assistance, producing a Human-Hybrid Powered Vehicle (H2PV). A model demonstrates significant weight reduction versus chain and sprocket drives, along with the elimination of an overrunning clutch or free-wheel, clean and quiet operation, weight efficient design, and use of modern lightweight materials like thermo-plastic plastics, glass, carbon or aramid fibers, and thermo-set plastics (polyurethanes).
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Lu¨neburg, Bernd, Meinolf Klocke, Stefan Kulig, and Frank Joswig. "Evaluation of Impact Loads of Clutch Engaging Within Single Shaft Applications for Power Generation." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-51063.
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Combined Cycle Power Plants (CCPP) in single shaft arrangements consist of a gas turbine, a generator and a steam turbine on one shaft line. In order to enhance the plant availability and operational flexibility, Siemens Fossil Power Generation introduces a switchable clutch between steam turbine and generator. The clutch is a synchronous self-shifting device that engages automatically at rated speed as soon as the steam turbine overruns the gas turbine-generator. It disengages automatically when the steam turbine speed drops below the speed of the gas turbine. A rather complicated mechanism consisting pawls and ratchets and a thread of helical splines including damper mechanisms is used to provide the required coupling functions. The primary reason for the clutch is to ensure independent gas turbine and steam turbine operation below steam turbine rated speed. The clutch is especially advantageous during startup and gas turbine simple-cycle operation. Next to these advantages, the clutch engaging processes could introduce significant impact loading to the shaft components which differ from other. Next to the normal engaging process fault cases like engaging processes after gas turbine trip at high acceleration values due to the gas turbine compressor losses must be sustained by all rotor train components. This paper documents a nonlinear torsional analysis of the single shaft arrangement to assess the impact loading due to clutch engaging processes. A dynamic three-mass-model of the clutch including nonlinear stiffness and damping functions is set up and applied for the simulations. The coupling of the translatory and the rotatory inertia effects of the main sliding component of the clutch has been taken into account. Different load case scenarios in different single shaft component arrangements respectively different inertia ranges of the steam turbine rotor train are investigated in detail by the transient analyses. Based on this procedure, it is ensured that the mechanical layout of the single shaft components is sufficiently designed to withstand all operational loads under normal and faulty operating conditions.