Relevant bibliographies by topics / Roller bearings

Academic literature on the topic 'Roller bearings'

Author: Grafiati
Published: 4 June 2021
Last updated: 24 February 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Roller bearings.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Roller bearings"

1

Tong, Van-Canh, and Seong-Wook Hong. "Study on the stiffness and fatigue life of tapered roller bearings with roller diameter error." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 2 (August 5, 2016): 176–88. http://dx.doi.org/10.1177/1350650116649889.

Full text
Abstract:
Geometric imperfection is a common problem in manufacturing of rolling element bearings. In particular, roller geometric errors frequently occur because a large number of rollers with relatively small size are engaged in a bearing. However, computational tools for rolling bearing characteristics take into account ideal bearings without any geometric error. In this study, the stiffness and fatigue life of tapered roller bearings were investigated with consideration for the effects of roller diameter errors possibly induced during manufacturing process. To this end, a general model for tapered roller bearings having rollers with diameter error (or defective rollers) was developed that can reflect the time-varying stiffness due to the roller error effects. The effects of the number of defective rollers, error magnitude, and position of defective rollers on the stiffness and fatigue life were investigated. Computational results showed that even small roller diameter errors appreciably alter the tapered roller bearings internal load distributions and therefore the stiffness and fatigue life of tapered roller bearings.
APA, Harvard, Vancouver, ISO, and other styles
2

Wei, Yan Gang, Yan Kui Liu, and Xiu Juan Zhang. "The Effects of Hollow Ratio on the Radial Bearing Properties of Pre-Loaded Cylindrical Roller Bearings." Advanced Materials Research 299-300 (July 2011): 1078–82. http://dx.doi.org/10.4028/www.scientific.net/amr.299-300.1078.

Full text
Abstract:
The finite element method is adopted to analyze the pre-loaded cylindrical roller bearings according to the theory of contact mechanics. The effects of hollow ratio on the radial stiffness of bearings, the maximum contact stress of rollers, and the maximum radial load of bearing are analyzed. The analysis results show that the smaller the hollowness is, the larger the radial stiffness of pre-loaded cylindrical roller bearings, the maximum contact stress of the rollers, and the maximum radial load of the bearing would be. Under different magnitude loads, the reasonable combination of interference magnitude with the hollowness can not only increase the stiffness of roller bearings, but also decrease the maximum stress of rollers, which provides a reference for the design and manufacture of pre-loaded cylindrical roller bearings.
APA, Harvard, Vancouver, ISO, and other styles
3

Qu, Tie, Qiang Bian, Guang Zeng, Chunjiang Zhao, Xiangyun Zhang, Lifeng Ma, and Ming Chen. "Study on Contact Force and Vibration Characteristics of Composite Cylindrical Roller Bearing." International Journal of Rotating Machinery 2022 (October 7, 2022): 1–10. http://dx.doi.org/10.1155/2022/7590924.

Full text
Abstract:
The composite cylindrical roller is composed of a hollow cylindrical roller and a filler body and is a new type of structure roller bearing. In order to explore the influence of different parameters on the contact characteristics and vibration characteristics of bearings, finite element models of static contact, modal analysis, and harmonic response analysis of composite cylindrical roller bearings were established based on ABAQUS software. The effects of filling rate, radial force, and the number of rollers on parameters such as contact force, contact stress, and natural frequency were studied. The results show that when the filling rate of the cylindrical roller increases from 0% to 70%, the natural frequency of bearing and the peak frequency of its harmonic response decrease, the force distribution in the contact area is also more uniform, and the maximum contact stress of the roller is reduced by 29.1%; the radial force has no effect on the peak frequency of the harmonic response of the bearing, but the increase of the radial force will increase the peak value of the response displacement, and the contact force and stress of the rollers will also increase. When the number of rollers increases from 11 to 15, the natural frequency and the peak frequency of harmonic response increase, the peak displacement decreases, the contact force distribution of the rollers in the bearing area is more uniform, and the maximum contact stress of the roller is reduced by 21.1%. The research result can provide a theoretical reference for the structural optimization and engineering application of elastic composite cylindrical roller bearings.
APA, Harvard, Vancouver, ISO, and other styles
4

Yu, Yongjian, Guoding Chen, Jishun Li, and Yujun Xue. "Influence of Geometric Error of Rollers on Rotational Accuracy of Cylindrical Roller Bearings." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 774–84. http://dx.doi.org/10.1051/jnwpu/20193740774.

Full text
Abstract:
As the rotation of roller bearings is carried out under geometrical constraint of the inner ring, outer ring and multiple rollers, the motion error of the bearing should also be resulted from geometric errors of bearing parts. Therefore, it is crucial to establish the relationship between geometric errors of bearing components and motion error of assembled bearing, which contributes to improve rotational accuracy of assembled bearing in the design and machining of the bearing. For this purpose, considering roundness error and dimension error of the inner raceway, the outer raceway and rollers, a prediction method for rotational accuracy of cylindrical roller bearings is proposed, and the correctness of the proposed prediction method is verified by experimental results. The influences of roller's geometric error distribution, roller's roundness error and the number of rollers on the runout value of inner ring are investigated. The results show that, the roller arrangement with different geometric errors has a significant impact on rotational accuracy of cylindrical roller bearings. The rotational accuracy could be improved remarkably when multiple rollers with different dimension error are distributed alternately according to the size error. Even-order roundness error of rollers has a significant effect on the rotational accuracy, and the decrease level depends on the orders of roundness errors of bearing parts and the number of rollers. But odd-order roundness error of rollers has almost no effect on the rotational accuracy. The rotational accuracy of assembled bearing would be significantly improved or decreased when even order harmonic of rollers and the number of rollers satisfy specific relationships. The greater the order of roundness error of the rollers, the more severe the influence of the roller number on rotational accuracy of assembled bearing. The rotational accuracy can not be always improved with the increase of the number of rollers.
APA, Harvard, Vancouver, ISO, and other styles
5

Gupta, P. K. "On the Geometrical Imperfections in Cylindrical Roller Bearings." Journal of Tribology 110, no. 1 (January 1, 1988): 13–18. http://dx.doi.org/10.1115/1.3261553.

Full text
Abstract:
Computer simulations of the dynamics performance of roller bearings, as obtained by the computer code ADORE, are used to model the infuence of race out-of-roundness, race taper and centrality of land on partly crowned rollers. Both oil and solid lubricated high-speed roller bearings are considered and the overall performance parameters, such as, bearing life, heat generation, cage interactions and race flange wear due to roller skew and tilt, are correlated to the magnitude of the various geometrical imperfections. Thus the strength of computer modeling approach to optimization of geometrical tolerances in cylindrical roller bearings is demonstrated.
APA, Harvard, Vancouver, ISO, and other styles
6

HE, Peiyu, Yi DING, Yun WANG, Fuzhu LI, Weili LIU, and Hua WANG. "analysis method of carrying capacity accuracy of three-row roller slewing bearing." Mechanics 28, no. 4 (August 30, 2022): 266–72. http://dx.doi.org/10.5755/j02.mech.29914.

Full text
Abstract:
Three-row roller slewing bearings are one of the critical core components of large rotating equipment. Heavy-duty conditions have extremely high requirements for the carrying capacity. The new load capacity analysis method proposed in this paper can effectively improve the accuracy and efficiency of the carrying capacity analysis of three-row roller slewing bearings. The three-row roller slewing bearing solid rollers are replaced in the model by the upper and lower halves of the rollers and two springs. The local contact model of the three-row roller slewing bearing was established and verified by the Hertz contact theory. The overall finite element model of the three-row roller slewing bearing was verified by strain tests. The new method can calculate the stress and strain distribution, load distribution, and deformation of the entire circle of the three-row roller slewing bearing and reduce the mesh number of the finite element of the overall model. Roller chamfer can also be considered closer to the actual working conditions and improves calculation efficiency and accuracy.
APA, Harvard, Vancouver, ISO, and other styles
7

Tong, Van-Canh, Sun-Woong Kwon, and Seong-Wook Hong. "Fatigue life of cylindrical roller bearings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 231, no. 5 (September 7, 2016): 623–36. http://dx.doi.org/10.1177/1350650116668767.

Full text
Abstract:
This paper dealt with the fatigue life of cylindrical roller bearings with several significant error sources that may occur during installations. A four degree-of-freedom quasi-static model for cylindrical roller bearings was developed, which took into account potential error sources such as angular misalignment, axial offset, and radial clearance, together with inertial loading by rotational speed and induced moment loads. A 3D contact model was employed to provide contact pressure distributions in rolling elements. The fatigue life of a cylindrical roller bearing was analyzed as a function of angular misalignment under various loading conditions. Then, the fatigue life analysis was extended to the combined effects of radial clearance, axial offset, and the number of rollers, along with angular misalignment. The computational results showed the significance of each error source on fatigue life. They further showed that cylindrical roller bearing fatigue life maximized when the radial clearances were slightly negative, and that it increased almost linearly with the number of rollers.
APA, Harvard, Vancouver, ISO, and other styles
8

Wang, Zhi Wei, Ling Qin Meng, Wen Si Hao, and E. Zhang. "Fesability Analysis of Solving Contact Problem of Roller Bearing by Finite Element Method." Advanced Materials Research 145 (October 2010): 68–72. http://dx.doi.org/10.4028/www.scientific.net/amr.145.68.

Full text
Abstract:
Contact problem is one of the most basic problems in the analysis of roller bearings, and the analysis and computation of contact stress and contact deformation are of great importance in roller bearing design. To solve the contact problems of roller bearing, we could use the Traditional method-- Hertz theory, the traditional method to solve the contact problems of roller bearings, is limited in the precision and unable to show the distribution characteristic of stress in contact area.In this paper, we use Finite Element Analysis software ANSYS to do research on contact problem of tapered roller bearing 3811/750/HC, and by means of comparison with the results gained by the Hertz theory we prove the feasibility of roller bearing contact problem by Finite Element Method. Hence, a more efficient method of improving the service life of rollers is got.
APA, Harvard, Vancouver, ISO, and other styles
9

Wang, Zhi Wei, Ling Qin Meng, Wen Si Hao, and E. Zhang. "Finite Element Method Analysis and Optimal Design of Roller Convexity of Tapered Roller Bearing." Advanced Materials Research 139-141 (October 2010): 1079–83. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1079.

Full text
Abstract:
The different designs of rollers with varied convexity give different stress distribution and elastic deformation. It is directly related to the load capability and the life length of the roller bearing. With the Finite Element Method(FEM), by analyzing the stress distribution of roller busbar and raceway contact area in the design of different rollers with varied convexity of tapered roller bearing, the paper gets the best solution for the design of convexity of tapered rollers and the cause of roller bearings’ early destroy. The optimal result shows that the service life of this bearing has been improved by 93%. Hence, a more efficient method of improving the service life of rollers is got.
APA, Harvard, Vancouver, ISO, and other styles
10

Zhang, Qing, Jun Luo, Xiang-yu Xie, Jin Xu, and Zhen-huan Ye. "Experimental Study on the Skidding Damage of a Cylindrical Roller Bearing." Materials 13, no. 18 (September 14, 2020): 4075. http://dx.doi.org/10.3390/ma13184075.

Full text
Abstract:
As large-scale rotating machines develop toward high rotating speed and high power–weight ratio, skidding damage has become one of the major initial failure modes of cylindrical roller bearings. Therefore, understanding the skidding damage law is an effective way to ensure the safety of machines supported by cylindrical roller bearings. To realize the skidding damage, a high-speed rolling bearing test rig that can simulate the actual operating conditions of aviation bearings was used in this paper, and the skidding damage dynamic behaviors of cylindrical roller bearings were investigated. In addition, to ensure the accuracy of the obtained skidding damage mechanism, the cylindrical roller bearing was carefully inspected by microscopic analysis when the skidding damage occurred. Out results show that instantaneous increases in friction torque, vibration acceleration, and temperature are clearly observed when the skidding damage occurs in the cylindrical roller bearing. Furthermore, under the conditions of inadequate lubrication and light load, the critical speed of skidding damage is rather low. The major wear mechanisms of skidding damage include oxidation wear, abrasive wear, and delamination wear. The white layers are found locally in the inner ring and rollers under the actions of friction heat and shear force.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Roller bearings"

1

Liu, Chao-Shih. "Fault detection of rolling element bearings /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/7064.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

TU, MINGHUI. "Validation and modeling of power losses of NJ406 cylindrical roller bearings." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193590.

Full text
Abstract:
I de flesta maskiner används lager för att ta upp krafter från roterande komponenter. I en växellåda används lager för att ge axlarna möjlighet att rotera fritt och att begränsa deras rörlighet i axiell och radiell led. För att öka växellådors prestanda är det viktigt att minimera effektförluster och att ha en hög tillförlitliglitlighet. Effektförluster orsakade av lager kan vara betydande i växellådor. Att kunnaprediktera effektförlusterna i lager mera exakt kan ge en bättre översikt av fördelningen av effektförluster i växellådor och för att förbättra deras prestanda. rullager. Huvudsyftet med det här projektet är att ta fram en friktionsmodell för NJ 406 cylindriska rullager. Experiment utfördes i en omgjord kugghjulsrigg, där parametrar som varvtal, last och oljenivåer varierades. Baserat på resultat från de utförda experimenten, jämfördes de med tre redan framtagna lagermodeller från Palmgren, Harris och SKF. Den huvudsakliga forskningsfrågan separerades i fyra delfrågor där analys och jämförelse gjordes mellan de existerande modellerna och utförda experiment. De fyra delfrågorna som undersöktes var; lastoberoende friktionsförluster, lastberoende friktionsförluster, mätosäkerhet och modellering. Oljenivåns, oljetypens, oljetemperaturens, varvtalets och lastens inverkan på lagrens friktionsrespons undersöktes också. Resultaten från mätosäkerhetsanalysen visar att experimenten i det här projektet är repeterbara och att det är möjligt att utveckla nya lagermodeller genom att använda resultaten från de utförda experimenten. Baserat på mätresultaten, passar de lastoberoende friktionsförlusterna från Harris modell bäst. En ny modell för lastberoende förluster utvecklades eftersom ingen av de tre existerande modellerande passar mätresultaten. Därför utvecklades en ny modell som kombinerar Harris modell för lastoberoende lagerförluster och en ny modell lastberoende friktionsförluster.
In most of machines, rotating parts are supported by many types of bearings which may have different requirements. In a gearbox, bearings are normally used to support gear shafts which allow the shafts to rotate freely and limit the axial and radial motion of the shafts. For improving of gearbox performance, it is important to minimize power losses and have high reliability. Power losses caused by bearings can be significant in gearbox system. To be able to predict bearing power losses accurately can give a better overview of the distribution of power losses in the system and is helpful for improving of gearbox performance. The main purpose of this project is to develop an accurate NJ 406 cylindrical roller bearing friction torque model. Numerous experiments were performed on a bearing test rig modified from a back-to-back gear test rig under different conditions, such as different rotating speeds, different loads, different oil level, etc. Based on the results from the experiments, analysis of three existing models, Palmgren, Harris and SKF, were performed. By separating the main research question into four sub research questions, the analysis and comparing between existing models and experimental data were also separated into load independent friction torque analysis, load dependent friction torque analysis, precision analysis and modeling. The influences of oil level, oil type, oil temperature, rotating speed and load on bearing friction torque were also studied. The results of precision analysis show the results of experiments in this project are repeatable and it is able to develop new bearing models by using these experimental results. Based on the experimental data, after modified, the load independent friction torque from Harris model fits the experimental data well. A new model of load dependent bearing friction torque was developed since none of the three existing models fit the experimental data. Therefore, a new NJ 406 cylindrical roller bearing friction torque model was developed which is modified Harris model for load independent friction torque and the new model for load dependent friction torque.
APA, Harvard, Vancouver, ISO, and other styles
3

Osorno, Daniel. "Rolling element skew measurement in a spherical roller bearing utilizing a CPD probe." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-08242005-140539/.

Full text
Abstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2006.
Steven Danyluk, Committee Chair ; David Sanborn, Committee Member ; Shreyes Melkote, Committee Member. Includes bibliographical references.
APA, Harvard, Vancouver, ISO, and other styles
4

Qian, Weihua [Verfasser]. "Dynamic simulation of cylindrical roller bearings / Weihua Qian." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1049572718/34.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Noury, Pourya. "On failure of high strength steel bridge roller bearings." Doctoral thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65215.

Full text
Abstract:
This thesis is concerned with failure analysis of high strength steel bridge roller bearings.Paper Adescribes how the commonly used Hertz formulas for contact stresses underestimate the actual stresses in practice due to temperature differences, misalignments and other construction-related conditions. In this paper, finite element analyses of bridge roller bearings were carried out to investigate the accuracy of the traditional roller bearing design rules in view of issues such as girder deformability, misalignment imperfections and material nonlinearity. The results first indicated that roller bearings develop contact stress concentrations at the outer edges of the rollers. Second, it was shown that the contact stresses are very sensitive to misalignment imperfections between the bridge girder and the abutment. Third, it was shown that the roller bearings develop inelastic deformation at relatively low loads in relation to the design load.In Paper B, the finite element method was employed to gain an understanding of the behaviour of a cracked bridge roller bearing in service. The cracked roller was considered as a two-dimensional edge-cracked disk subjected to a diametrical compressive line load. The crack parameters, stress intensity factor Mode I, KI and Mode II ,KII were calculated for the relevant load configuration and angle of disk rotation. The calculated data for KIwere also used to check the accuracy of approximate stress intensity factor solutions reported earlier for Mode I. For plain Mode I loading very good agreement was found between the obtained results and data presented in Schindler and Morf (1994). Paper Cis aimed at finding the likely failure mechanism of a bridge roller bearing made of high strength martensitic stainless steel. Spectroscopy and finite element stress analysis of the roller indicated that an initial radial surface crack, found at an end face of the roller and close to the contact region, was induced by stress corrosion cracking (SCC). The initial crack subsequently changed shape and increased in size under growth through fatigue and finally formed a quarter-circle radial crack centred on the end face corner of the roller. Numerically computed stress intensity factors for the final crack showed that crack loading was predominantly in Mode II. For a crack size as observed on the fracture surface, the maximum service load, as specified by the manufacturer, enhanced by a certain roller bearing misalignment effect, was sufficient for failure through fracture.InPaper D, after a brief summary of the history of high strength stainless steel bearings, the paper reviews service experience of failed bearings in Sweden and elsewhere. Accompanying finite element analyses were performed in order to gain better insight into the likely failure mechanism. Finally, thiscomprehensive review leads to a conclusion that identifies the causes of the failures occurred and makes some recommendations.
APA, Harvard, Vancouver, ISO, and other styles
6

Ciabattoni, Dino. "A CADAM interface for the computer-aided selection of Timken tapered roller bearings." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/101171.

Full text
Abstract:
This thesis presents an interactive computer-graphics geometry interface that simplifies the tapered roller bearing selection procedure. An applications program has been developed that links the CADAM data base to SELECT-A-NALYSIS (SAN), Timken's bearing selection and analysis program. The independent modular format of the SAN preprocessor eliminates the ambiguity and difficulty associated with conventional bearing selection routines. Interactive-graphic menu selection allows program logic to be followed while design geometry is selected from a CADAM model. In addition to the discussion of the program development and structure, step-by-step instructions for an example problem are provided. Complete program listings are also supplied to facilitate future additions and modifications to the preprocessor.
M.S.
APA, Harvard, Vancouver, ISO, and other styles
7

Moodie, Craig Alexander Simpson. "An investigation into the condition monitoring of large slow speed slew bearings." Access electronically, 2009. http://ro.uow.edu.au/theses/3035.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Ribadeneira, M. Xavier. "Ball bearing diagnostics with multiple sensors." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18963.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Billington, Scott Alexander. "Sensor and machine condition effects in roller bearing diagnostics." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17796.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Schiller, David (David Andrew) 1975. "Investigation of methods for compensating for setting problems of tapered roller bearings in dimensionally unstable bearing housings." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80023.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Roller bearings"

1

American dream: One hundred years of American Roller Bearing Company. Virginia Beach, VA: Donning Co. Publishers, 2012.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

L, Hasbargen, Weigand, Brändlein J, and FAG Kugelfischer Georg Schäfer KGaA., eds. Ball and roller bearings: Theory, design, and application. 2nd ed. München: R. Oldenbourg, 1985.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Eschmann, P. Ball and roller bearings: Theory, design, and application. 2nd ed. München: Oldenbourg, 1985.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Institute, American National Standards. Shaft and housing fits for metric radial ball and roller bearings (except tapered roller bearings) conforming to basic boundary plans. Washington, D.C: Anti-Friction Bearing Manufacturers Association, 1988.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

Nguyen-Schäfer, Hung. Computational Tapered and Cylinder Roller Bearings. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Society of Tribologists and Lubrication Engineers. Technical Committee on Bearings and Bearing Lubrication. Interpreting service damage in rolling type bearings: A manual on ball & roller bearing damage. Park Ridge, Ill: American Society of Tribologists and Lubrication Engineers, 1993.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

Floberg, Leif. On the design of spherical roller bearings. Lund: Lund Technical University, 1990.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

United States International Trade Commission. Tapered roller bearings and parts thereof, and certain housings incorporating tapered rollers from Italy and Yugoslavia: Determinations of the Commission in investigations nos. 731-TA-342 and 346 (final) under the Tariff Act of 1930, together with the information obtained in the investigations. Washington, DC: U.S. International Trade Commission, 1987.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

United States International Trade Commission. Tapered roller bearings and parts thereof, and certain housings incorporating tapered rollers from Italy and Yugoslavia: Determinations of the Commission in investigations nos. 731-TA-342 and 346 (final) under the Tariff Act of 1930, together with the information obtained in the investigations. Washington, DC: U.S. International Trade Commission, 1987.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

Tapered roller bearings and parts thereof, and certain housings incorporating tapered rollers from Hungary, Italy, Japan, the People's Republic of China, Romania, and Yugoslavia: Determinations of the Commission in investigations nos. 731-TA-341 through 346 (preliminary) under the Tariff Act of 1930, together with the information obtained in the investigations. Washington, DC: U.S. International Trade Commission, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Roller bearings"

1

Nguyen-Schäfer, Hung. "Tapered Roller Bearings." In Computational Tapered and Cylinder Roller Bearings, 1–39. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_1.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Nguyen-Schäfer, Hung. "Cylinder Roller Bearings." In Computational Tapered and Cylinder Roller Bearings, 41–71. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_2.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Sachs, Neville W. "Ball and Roller Bearings." In Practical Plant Failure Analysis, 231–79. Second edition. | Boca Raton, FL : CRC Press/Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/9780429451041-10.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Cowles, J. H., and C. A. Houle. "Roller Profile Development for an Axially Loaded, Single Row Spherical Roller Bearing in an Oscillating Application." In Rolling Element Bearings, 47–70. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2011. http://dx.doi.org/10.1520/stp103891.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Nguyen-Schäfer, Hung. "Loads Acting on Gears and Bearings." In Computational Tapered and Cylinder Roller Bearings, 73–77. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Nguyen-Schäfer, Hung. "Bearing Endplay Over Operating Temperatures." In Computational Tapered and Cylinder Roller Bearings, 79–86. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_4.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Nguyen-Schäfer, Hung. "Accelerated Load Spectrum." In Computational Tapered and Cylinder Roller Bearings, 87–94. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_5.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Nguyen-Schäfer, Hung. "Solving Nonlinear Equation Systems." In Computational Tapered and Cylinder Roller Bearings, 95–102. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05444-1_6.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Mazal, P., F. Hort, and F. Vlasic. "Acoustic Emission Diagnostics of Roller Bearings Damage." In Nondestructive Testing of Materials and Structures, 167–72. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0723-8_24.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Desnica, Eleonora, Aleksandar Ašonja, Ljiljana Radovanović, Ivan Palinkaš, and Imre Kiss. "Selection, Dimensioning and Maintenance of Roller Bearings." In 31st International Conference on Organization and Technology of Maintenance (OTO 2022), 133–42. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-21429-5_12.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Roller bearings"

1

Weiser, Tobias, and Burkhard Corves. "Modeling of Roller Bearings." In The 12th International Modelica Conference, Prague, Czech Republic, May 15-17, 2017. Linköping University Electronic Press, 2017. http://dx.doi.org/10.3384/ecp17132765.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Ghalamchi, Behnam, Jussi T. Sopanen, and Aki M. Mikkola. "Dynamic Model of Spherical Roller Bearing." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12102.

Full text
Abstract:
Rolling element bearings are essential machine elements in the rotating machinery. Extensive research has been conducted to study the dynamics of ball bearings, while studies related to spherical roller bearings are short-shrifted. On the other hand, the number of industrial applications that utilize spherical roller bearings has been increasing constantly. This is due to self-aligning nature and high-load capacity of spherical roller bearings. Typical applications are paper machines, steel rolling, marine equipment, geared transmissions and modern high power wind turbines. This study introduces a three-degree-of-freedom spherical roller bearing model that is computationally efficient, and it is designed to be used in the transient simulations of complete rotor-bearing systems. In the proposed model, the bearing forces are calculated as a function of contact deformation and bearing geometry parameters according to the non-linear Hertzian contact theory. In the numerical results, the important bearing design parameters such as diametral clearance, number of rollers and osculation are studied. Existence of varying compliance (VC) vibrations and the capability of the proposed model in the transient simulations of rotor-bearing systems are demonstrated. The bearing model is verified by using commercial bearing analysis software. Future improvements and model extension possibilities are also discussed.
APA, Harvard, Vancouver, ISO, and other styles
3

Saranu, Ravikumar. "Condition monitoring of roller bearings." In THIRD INTERNATIONAL CONFERENCE ON INVENTIVE MATERIAL SCIENCE APPLICATIONS: ICIMA 2020. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0026626.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Montalvo, Joseph, Constantine Tarawneh, and Arturo A. Fuentes. "Vibration-Based Defect Detection for Freight Railcar Tapered-Roller Bearings." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6210.

Full text
Abstract:
The railroad industry currently utilizes two wayside detection systems to monitor the health of freight railcar bearings in service: The Trackside Acoustic Detection System (TADS™) and the wayside Hot-Box Detector (HBD). TADS™ uses wayside microphones to detect and alert the conductor of high risk defects. Many defective bearings may never be detected by TADS™ due to the fact that a high risk defect is considered a spall which spans more than 90% of a bearing’s raceway, and there are less than 20 systems in operation throughout the United States and Canada. Much like the TADS™, the HBD is a device that sits on the side of the rail tracks and uses a non-contact infrared sensor to determine the temperature of the train bearings as they roll over the detector. The accuracy and reliability of the temperature readings from this wayside detection system have been concluded to be inconsistent when comparing several laboratory and field studies. The measured temperatures can be significantly different from the actual operating temperature of the bearings due to several factors such as the class of railroad bearing and its position on the axle relative to the position of the wayside detector. Over the last two decades, a number of severely defective bearings were not identified by several wayside detectors, some of which led to costly catastrophic derailments. In response, certain railroads have attempted to optimize the use of the temperature data acquired by the HBDs. However, this latter action has led to a significant increase in the number of non-verified bearings removed from service. In fact, about 40% of the bearings removed from service in the period from 2001 to 2007 were found to have no discernible defects. The removal of non-verified (defect-free) bearings has resulted in costly delays and inefficiencies. Driven by the need for more dependable and efficient condition monitoring systems, the University Transportation Center for Railway Safety (UTCRS) research team at the University of Texas Rio Grande Valley (UTRGV) has been developing an advanced onboard condition monitoring system that can accurately and reliably detect the onset of bearing failure. The developed system currently utilizes temperature and vibration signatures to monitor the true condition of a bearing. This system has been validated through rigorous laboratory testing at UTRGV and field testing at the Transportation Technology Center, Inc. (TTCI) in Pueblo, CO. The work presented here provides concrete evidence that the use of vibration signatures of a bearing is a more effective method to assess the bearing condition than monitoring temperature alone. The prototype bearing condition monitoring system is capable of identifying a defective bearing with a defect size of less than 6.45 cm2 (1 in2) using the vibration signature, whereas, the temperature profile of that same bearing will indicate a healthy bearing that is operating normally.
APA, Harvard, Vancouver, ISO, and other styles
5

Hoeprich, Michael R. "Grease Performance in Tapered Roller Bearings." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-64352.

Full text
Abstract:
To gain insight into the physical aspects of grease lubrication, nine greases with different oil viscosity and thickener combinations were tested in a tapered rolling element bearing under a light thrust load at speeds of 1800 and 3600 RPM. Bearings were run for thirty days or until a 150°C rib temperature was reached. Using SEM analysis, thickener samples were taken after testing from the rib/roller and raceway contacts for comparison with the thickener in new grease. A post test infrared technique was also used to evaluate grease thickness at the rib/roller contact and was compared with calculated film thickness. Bearing operating temperatures were then compared with grease base oil viscosity and thickener type.
APA, Harvard, Vancouver, ISO, and other styles
6

Dadouche, Azzedine, and Rami Kerrouche. "Roller Bearing Skidding for Aero-Engine Applications: All-Steel Versus Hybrid Bearings." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-83532.

Full text
Abstract:
Abstract Roller bearings operating under light loads may suffer from skidding. The latter is more pronounced as the speed increases and may result in extensive wear and reduced service life of the bearing. The main objective of this study is to analyze skidding occurrence in a custom-made all-steel M50 bearing and a hybrid roller bearing subjected to the same operating conditions. The test bearings have a bore diameter of 90 mm, an outer diameter of 125 mm and 26 rollers. The hybrid bearing features silicon nitride (Si3N4) rollers and steel rings (M50 outer ring and M50-NIL inner ring). The bearings feature special channels to allow for under race lubrication of the bearing components in relative motion. A suite of sensors were used and installed to detect skidding and monitor the overall performance of the test bearing such as vibrations and temperature. The effect of the radial applied load, shaft rotational speed and oil flow rate on roller skidding have been investigated and discussed. Slip ratio for each of the bearings under various speed-load combinations was also determined and analyzed. Turbo oil 2380 was used to lubricate the test bearings at a constant temperature of 77°C. Tests were conducted on a high-speed rolling bearing test rig and data was recorded using a 24-bit data acquisition system.
APA, Harvard, Vancouver, ISO, and other styles
7

Gonzalez, Amy, Constantine Tarawneh, Ping Hu, Joseph A. Turner, and Brent M. Wilson. "Tracking of Spall Deterioration on Tapered Roller Bearings." In 2015 Joint Rail Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/jrc2015-5793.

Full text
Abstract:
Fatigue spall initiation is one of the major modes of premature bearing failure. The spall initiation is often exacerbated by the presence of impurities in the near-surface region (∼400 μm) of the bearing raceways. Once a spall initiates, it can propagate rapidly, leading to abnormal bearing operation and possible catastrophic failure if not detected early. Testing performed at the University of Texas-Pan American (UTPA) has focused on ultrasonically scanned tapered roller bearings found to have inclusion content within 400 μm of the surface of the raceways. These bearings undergo accelerated service life tests in which spall initiation is detected and tracked over time while documenting spall growth. The work presented here provides several study cases that document the spall initiation and propagation on ultrasonically scanned tapered roller bearing components. Results show that spalls generally initiate on locations corresponding to sites of subsurface inclusions, and they grow many times their original size within relatively short operating periods. The study also shows that spalls tend to initiate and propagate at a faster rate on bearing cups (outer rings) than on cones (inner rings).
APA, Harvard, Vancouver, ISO, and other styles
8

Kang, Young Sup, Ryan D. Evans, and Gary L. Doll. "Roller-Raceway Slip Simulations of Wind Turbine Gearbox Bearings Using Dynamic Bearing Model." In STLE/ASME 2010 International Joint Tribology Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ijtc2010-41191.

Full text
Abstract:
A six degree of freedom dynamic bearing model (DBM) has been used to simulate roller-raceway slip for a cylindrical roller bearing used in an intermediate shaft location of a wind turbine gearbox. The DBM simulates the motion of bearing components such as an inner raceway, a cage, and cylindrical rollers. Radial internal clearance and operating conditions such as load and speed were varied in order to identify the most critical parameters governing roller-raceway slip. The results indicate that significant slip occurs during rapid transient accelerations and decelerations, but these high slip conditions decay to a much lower level of slip at steady state. The results also demonstrate that extreme slip occurs for low load and high speed conditions because of concomitant contact area reduction and traction loss at the roller-raceway interfaces.
APA, Harvard, Vancouver, ISO, and other styles
9

Clasby, Dustin, and Monique Stewart. "Bearing Grease Degradation Related to Water and Roller Bluing." In 2018 Joint Rail Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/jrc2018-6136.

Full text
Abstract:
Bearing degradation and defects can result in a premature failure. Water ingress into the bearing is a factor for premature degradation, as water may corrupt internal parts and degrade the bearing grease. This paper presents the investigation of the properties of grease degradation from bearings with water-related degradations. This research provides insight into the internal state of bearings that have been replaced due to grease degradation as a result of water ingress. Separately, the railroad industry has observed bearing roller “bluing” or “lube staining.” This discoloration may be a harmless surface effect, or it may be similar to heat bluing. Determining true metallurgical effects may lead to the understanding between these two different types of “bluing”. To study bearings with water-related lubrication degradation, grease samples were collected from two populations of bearing lubrication at bearing service locations. One population contains bearings identified with water-related damage, and a second population is a control set of bearings. Primary grease analysis was done per ASTM 7918, providing metrics of wear, contamination, consistency, and oxidative properties. Additional testing was performed where results indicated utility; including measurements of anti-oxidant remaining in grease and microscopic analysis of wear particles in the grease. “Bluing” or “lube stain” bearing components were examined through analysis of lubrication and metallurgical metrics. Collections of samples from bearing shops included representative small amounts of grease and “blued” steel parts from bearings exhibiting surface discoloration. A second sample set included steel parts and grease samples from a control set of bearings. A third set of rollers were heat blued in the lab. Lube stained rollers and control set rollers were tested for metallurgical changes. Analysis of the bearing steel consisted of hardness and micro-hardness testing of polished samples, examination to compare microstructural features, and residual stress tests. The tests conducted in the investigation of water-related bearing grease degradation indicate a difference between bearings with “Water-Etch” and “Non-Verified” degradation modes based on ferrous debris levels in the grease. This difference is due to wear of the bearing material deposited in the grease. The tests conducted in the investigation of lube stain in bearings show lube stain does not affect any tested metallurgical material properties, other than surface discoloration.
APA, Harvard, Vancouver, ISO, and other styles
10

Anderson, Gerald B. "Acoustic Detection of Distressed Freight Car Roller Bearings." In ASME/IEEE 2007 Joint Rail Conference and Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/jrc/ice2007-40091.

Full text
Abstract:
Trackside Acoustic Detection System (TADS®) development spearheaded implementation of an acoustic freight car roller bearing detector whose purpose is to prevent in-service bearing failures (burned off journals and hot bearing detector train stops). The means of accomplishing this goal is by providing the user with a warning of internal bearing defects or degradation with component involvement and severity information. The Transportation Technology Center, Inc. (TTCI) began the TADS® development process in 1994 with basic research into bearing defect acoustic emissions. Subsequently, TTCI conducted prototype testing on a North American railroad, constructed and installed of several international beta test systems, and finally has sold production systems in North America and internationally. There are currently about 40 TADS® sites in operation world-wide with 2.0 or more systems scheduled for installation in 2007. The original mission for TADS® in North America was an early warning of bearing degradation to allow for scheduled maintenance, but after initial evaluation, this mission enlarged to include notification of potentially high risk bearings. The high risk bearing is defined as one with fairly large areas of internal damage and at an increased risk of overheating or failing in service. The high risk bearing has a different acoustic signature, dissimilar to that of smaller defects. This paper will outline the change in mission for this detector and describe the development of an improved capability for detecting these high risk bearings.
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Roller bearings"

1

Bayba, Andrew J., David N. Siegel, Kwok Tom, and Derwin Washington. Health Assessment and Fault Classification of Roller Element Bearings. Fort Belvoir, VA: Defense Technical Information Center, July 2012. http://dx.doi.org/10.21236/ada568919.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Vaes, David, Yi Guo, Pietro Tesini, and Jonathan A. Keller. Investigation of Roller Sliding in Wind Turbine Gearbox High-Speed-Shaft Bearings. Office of Scientific and Technical Information (OSTI), May 2019. http://dx.doi.org/10.2172/1524765.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Jaques, Al. D0 Carriage Roller Bearing Measurements. Office of Scientific and Technical Information (OSTI), February 1989. http://dx.doi.org/10.2172/1031146.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Keller, J., Y. Guo, and B. McNiff. Gearbox Reliability Collaborative High Speed Shaft Tapered Roller Bearing Calibration. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1107454.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Kolarik, Robert V. II, Charles W. Shattuck, and Anthony P. Copper. EVALUATION OF A LOW FRICTION - HIGH EFFICIENCY ROLLER BEARING ENGINE. Office of Scientific and Technical Information (OSTI), June 2009. http://dx.doi.org/10.2172/958085.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Manor, M. J., and S. J. Piercey. Whole-rock lithogeochemistry, Nd-Hf isotopes, and in situ zircon geochemistry of VMS-related felsic rocks, Finlayson Lake VMS district, Yukon. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328992.

Full text
Abstract:
The Finlayson Lake district in southeastern Yukon is composed of a Late Paleozoic arc-backarc system that consists of metamorphosed volcanic, plutonic, and sedimentary rocks of the Yukon-Tanana and Slide Mountain terranes. These rocks host >40 Mt of polymetallic resources in numerous occurrences and styles of volcanogenic massive sulphide (VMS) mineralization. Geochemical and isotopic data from these rocks support previous interpretations that volcanism and plutonism occurred in arc-marginal arc (e.g., Fire Lake formation) and continental back-arc basin environments (e.g., Kudz Ze Kayah formation, Wind Lake formation, and Wolverine Lake group) where felsic magmatism formed from varying mixtures of crust- and mantle-derived material. The rocks have elevated high field strength element (HFSE) and rare earth element (REE) concentrations, and evolved to chondritic isotopic signatures, in VMS-proximal stratigraphy relative to VMS-barren assemblages. These geochemical features reflect the petrogenetic conditions that generated felsic rocks and likely played a role in the localization of VMS mineralization in the district. Preliminary in situ zircon chemistry supports these arguments with Th/U and Hf isotopic fingerprinting, where it is interpreted that the VMS-bearing lithofacies formed via crustal melting and mixing with increased juvenile, mafic magmatism; rocks that were less prospective have predominantly crustal signatures. These observations are consistent with the formation of VMS-related felsic rocks by basaltic underplating, crustal melting, and basalt-crustal melt mixing within an extensional setting. This work offers a unique perspective on magmatic petrogenesis that underscores the importance of integrating whole-rock with mineral-scale geochemistry in the characterization of VMS-related stratigraphy.
APA, Harvard, Vancouver, ISO, and other styles
7

Liseroudi, M. H., O. H. Ardakani, P. K. Pedersen, R. A. Stern, J M Wood, and H. Sanei. Diagenetic and geochemical controls on H2S distribution in the Montney Formation, Peace River region, western Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329785.

Full text
Abstract:
The Lower Triassic Montney Formation is a major siltstone dominated unconventional tight gas play in the Western Canadian Sedimentary Basin (WCSB). In the Peace River region, the Montney Formation contains a regionally variable amount of hydrogen sulfide (H2S) in gas-producing wells with western Alberta's wells having the highest concentrations. Previous studies on the source and distribution of H2S in the Montney Formation mainly focused on variations of H2S concentration and its relationship with other hydrocarbon and non-hydrocarbon gases, sulfur isotope composition of H2S, as well as organo-sulfur compounds in the Montney Formation natural gas. None of those studies, however, focused on the role of diagenetic and geochemical processes in the formation of dissolved sulfate, one of the two major ingredients of H2S formation mechanisms, and pyrite within the Montney Formation. According to the results of this study, the Montney Formation consists of two different early and late generations of sulfate minerals (anhydrite and barite), mainly formed by the Montney Formation pore water and incursion of structurally-controlled Devonian-sourced hydrothermal sulfate-rich fluids. In addition, pyrite the dominate sulfide mineral, occurred in two distinct forms as framboidal and crystalline that formed during early to late stages of diagenesis in western Alberta (WAB) and northeast British Columbia (NEBC). The concurrence of the late-stage anhydrite and barite and various types of diagenetic pyrite with high H2S concentrations, particularly in WAB, their abundance, and spatial distribution, imply a correlation between the presence of these sulfate and sulfide species and the diagenetic evolution of sulfur in the Montney Formation. The sulfur isotope composition of anhydrite/barite, H2S, and pyrite demonstrates both microbial and thermochemical sulfate reduction (MSR and TSR) controlled the diagenetic sulfur cycle of the Montney Formation. The relationship between the delta-34S values of the present-day produced gas H2S and other sulfur-bearing species from the Montney and other neighboring formations verifies a dual native and migrated TSR-derived origin for the H2S gas with substantial contributions of in situ H2S in the Montney reservoir.
APA, Harvard, Vancouver, ISO, and other styles
8

Grumet, Rebecca, Rafael Perl-Treves, and Jack Staub. Ethylene Mediated Regulation of Cucumis Reproduction - from Sex Expression to Fruit Set. United States Department of Agriculture, February 2010. http://dx.doi.org/10.32747/2010.7696533.bard.

Full text
Abstract:
Reproductive development is a critical determinant of agricultural yield. For species with unisexual flowers, floral secualdifferentation adds additional complexity, that can influenec productivity. The hormone ethylene has long, been known to play a primary role in sex determination in the Cucumis species cucumber (C. sativus) and melon (C. melo). Our objectives were to: (1) Determine critical sites of ethylene production and perception for sex determination; (2) Identify additional ethylene related genes associated with sex expression; and (3) Examine the role of environment ami prior fruit set on sex expression, pistillate flower maturation, and fruit set. We made progress in each of these areas. (1) Transgenic melon produced with the Arabidopsis dominant negative ethylene perception mutant gene, etrl-1, under the control of floral primordia targeted promoters [AP3 (petal and stamen) and CRC (carpel and nectary)], showed that ethylene perception by the stamen primordia, rather than carpel primordia, is critical for carpel development at the time of sex determination. Transgenic melons also were produced with the ethylene production enzyme gene. ACS, encoding l-aminocyclopropane-lcarboylate synthase, fused to the AP3 or CRC promoters. Consistent with the etr1-1 results, CRC::ACS did not increase femaleness; however, AP3::ACS reduced or eliminated male flower production. The effects of AP3:ACS were stronger than those of 35S::ACS plants, demonstratin g the importance of targeted expression, while avoiding disadvantages of constitutive ethylene production. (2) Linkage analysis coupled with SNP discovery was per formed on ethylene and floral development genes in cucumber populations segregating for the three major sex genes. A break-through towards cloning the cucumber M gene occurred when the melon andromonoecious gene (a), an ACS gene, was cloned in 2008. Both cucumber M and melon a suppress stamen development in pistillate flowers. We hypothesized that cucumber M could be orthologous to melon a, and found that mutations in CsACS2 co-segregated perfectly with the M gene. We also sought to identify miRNA molecules associated with sex determination. miRNA159, whose target in Arabidopsis is GAMYB[a transcription factor gene mediating response to10 gibberellin (GA)], was more highly expressed in young female buds than male. Since GA promotes maleness in cucumber, a micro RNA that counteracts GAMYB could promote femaleness. miRNA157, which in other plants targets transcription factors involved in flower development , was expressed in young male buds and mature flower anthers. (3) Gene expression profiling showed that ethylene-, senescence-, stress- and ubiquitin-related genes were up-regulated in senescing and inhibited fruits, while those undergoing successful fruit set up-regulated photosynthesis, respiration and metabolic genes. Melon plants can change sex expression in response to environmental conditions, leading to changes in yield potential. Unique melon lines with varying sex expression were developed and evaluated in the field in Hancock, Wisconsin . Environmental changes during the growing season influenced sex expression in highly inbred melon lines. Collectively these results are of significance for understanding regulation of sex expression. The fact that both cucumber sex loci identified so far (F and M) encode isoforms of the same ethylene synthesis enzyme, underscores the importance of ethylene as the main sex determining hormone in cucumber. The targeting studies give insight into developmental switch points and suggest a means to develop lines with earlier carpel-bearing flower production and fruit set. These results are of significance for understanding regulation of sex expression to facilitate shorter growing seasons and earlier time to market. Field results provide information for development of management strategies for commercial production of melon cultivars with different sex expression characteristics during fruit production.
APA, Harvard, Vancouver, ISO, and other styles
9

Manulis-Sasson, Shulamit, Christine D. Smart, Isaac Barash, Laura Chalupowicz, Guido Sessa, and Thomas J. Burr. Clavibacter michiganensis subsp. michiganensis-tomato interactions: expression and function of virulence factors, plant defense responses and pathogen movement. United States Department of Agriculture, February 2015. http://dx.doi.org/10.32747/2015.7594405.bard.

Full text
Abstract:
Clavibactermichiganensissubsp. michiganensis(Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The goal of the project was to unravel the molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato. The genome of Cmm contains numerous genes encoding for extracellular serine proteases and cell wall degrading enzymes. The first objective was to elucidate the role of secreted serine proteases in Cmm virulence. Mutants of nine genes encoding serine proteases of 3 different families were tested for their ability to induce wilting, when tomato stems were puncture-inoculated, as compared to blisters formation on leaves, when plants were spray-inoculated. All the mutants showed reduction in wilting and blister formation as compared to the wild type. The chpCmutant displayed the highest reduction, implicating its major role in symptom development. Five mutants of cell wall degrading enzymes and additional genes (i.e. perforin and sortase) caused wilting but were impaired in their ability to form blisters on leaves. These results suggest that Cmm differentially expressed virulence genes according to the site of penetration. Furthermore, we isolated and characterized two Cmmtranscriptional activators, Vatr1 and Vatr2 that regulate the expression of virulence factors, membrane and secreted proteins. The second objective was to determine the effect of bacterial virulence genes on movement of Cmm in tomato plants and identify the routes by which the pathogen contaminates seeds. Using a GFP-labeledCmm we could demonstrate that Cmm extensively colonizes the lumen of xylem vessels and preferentially attaches to spiral secondary wall thickening of the protoxylem and formed biofilm-like structures composed of large bacterial aggregates. Our findings suggest that virulence factors located on the chp/tomAPAI or the plasmids are required for effective movement of the pathogen in tomato and for the formation of cellular aggregates. We constructed a transposon plasmid that can be stably integrated into Cmm chromosome and express GFP, in order to follow movement to the seeds. Field strains from New York that were stably transformed with this construct, could not only access seeds systemically through the xylem, but also externally through tomato fruit lesions, which harbored high intra-and intercellular populations. Active movement and expansion of bacteria into the fruit mesocarp and nearby xylem vessels followed, once the fruit began to ripen. These results highlight the ability of Cmm to invade tomato fruit and seed through multiple entry routes. The third objective was to assess correlation between disease severity and expression levels of Cmm virulence genes and tomato defense genes. The effect of plant age on expression of tomato defense related proteins during Cmm infection was analyzed by qRT-PCR. Five genes out of eleven showed high induction at early stages of infection of plants with 19/20 leaves compared to young plants bearing 7/8 leaves. Previous results showed that Cmm virulence genes were expressed at early stages of infection in young plants compared to older plants. Results of this study suggest that Cmm virulence genes may suppress expression of tomato defense-related genes in young plants allowing effective disease development. The possibility that chpCis involved in suppression of tomato defense genes is currently under investigation by measuring the transcript level of several PR proteins, detected previously in our proteomics study. The fourth objective was to define genome location and stability of virulence genes in Cmm strains. New York isolates were compared to Israeli, Serbian, and NCPPB382 strains. The plasmid profiles of New York isolates were diverse and differed from both Israeli and Serbian strains. PCR analysis indicated that the presence of putative pathogenicity genes varied between isolates and highlighted the ephemeral nature of pathogenicity genes in field populations of Cmm. Results of this project significantly contributed to the understanding of Cmm virulence, its movement within tomato xylem or externally into the seeds, the role of serine proteases in disease development and initiated research on global regulation of Cmm virulence. These results form a basis for developing new strategies to combat wilt and canker disease of tomato.
APA, Harvard, Vancouver, ISO, and other styles
10

Microbiology in the 21st Century: Where Are We and Where Are We Going? American Society for Microbiology, 2004. http://dx.doi.org/10.1128/aamcol.5sept.2003.

Full text
Abstract:
The American Academy of Microbiology convened a colloquium September 5–7, 2003, in Charleston, South Carolina to discuss the central importance of microbes to life on earth, directions microbiology research will take in the 21st century, and ways to foster public literacy in this important field. Discussions centered on: the impact of microbes on the health of the planet and its inhabitants; the fundamental significance of microbiology to the study of all life forms; research challenges faced by microbiologists and the barriers to meeting those challenges; the need to integrate microbiology into school and university curricula; and public microbial literacy. This is an exciting time for microbiology. We are becoming increasingly aware that microbes are the basis of the biosphere. They are the ancestors of all living things and the support system for all other forms of life. Paradoxically, certain microbes pose a threat to human health and to the health of plants and animals. As the foundation of the biosphere and major determinants of human health, microbes claim a primary, fundamental role in life on earth. Hence, the study of microbes is pivotal to the study of all living things, and microbiology is essential for the study and understanding of all life on this planet. Microbiology research is changing rapidly. The field has been impacted by events that shape public perceptions of microbes, such as the emergence of globally significant diseases, threats of bioterrorism, increasing failure of formerly effective antibiotics and therapies to treat microbial diseases, and events that contaminate food on a large scale. Microbial research is taking advantage of the technological advancements that have opened new fields of inquiry, particularly in genomics. Basic areas of biological complexity, such as infectious diseases and the engineering of designer microbes for the benefit of society, are especially ripe areas for significant advancement. Overall, emphasis has increased in recent years on the evolution and ecology of microorganisms. Studies are focusing on the linkages between microbes and their phylogenetic origins and between microbes and their habitats. Increasingly, researchers are striving to join together the results of their work, moving to an integration of biological phenomena at all levels. While many areas of the microbiological sciences are ripe for exploration, microbiology must overcome a number of technological hurdles before it can fully accomplish its potential. We are at a unique time when the confluence of technological advances and the explosion of knowledge of microbial diversity will enable significant advances in microbiology, and in biology in general, over the next decade. To make the best progress, microbiology must reach across traditional departmental boundaries and integrate the expertise of scientists in other disciplines. Microbiologists are becoming increasingly aware of the need to harness the vast computing power available and apply it to better advantage in research. Current methods for curating research materials and data should be rethought and revamped. Finally, new facilities should be developed to house powerful research equipment and make it available, on a regional basis, to scientists who might otherwise lack access to the expensive tools of modern biology. It is not enough to accomplish cutting-edge research. We must also educate the children and college students of today, as they will be the researchers of tomorrow. Since microbiology provides exceptional teaching tools and is of pivotal importance to understanding biology, science education in schools should be refocused to include microbiology lessons and lab exercises. At the undergraduate level, a thorough knowledge of microbiology should be made a part of the core curriculum for life science majors. Since issues that deal with microbes have a direct bearing on the human condition, it is critical that the public-at-large become better grounded in the basics of microbiology. Public literacy campaigns must identify the issues to be conveyed and the best avenues for communicating those messages. Decision-makers at federal, state, local, and community levels should be made more aware of the ways that microbiology impacts human life and the ways school curricula could be improved to include valuable lessons in microbial science.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Roller bearings' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography