A predesigned parabolic function of transmission errors for reduction of noise and vibration is provided. The stress analysis of the gear drive is performed using a three-dimensional finite element analysis. The contacting model is automatically generated. The developed theory is illustrated with numerical examples. A diagnostic tool for detecting damage to spur gears was developed.
Two different measurement technologies , wear debris analysis and vibration, were integrated into a health monitoring system for detecting surface fatigue pitting damage on gears. This integrated system showed improved detection and decision-making capabilities as compared to using individual measurement technologies. Experimental data were collected during experiments performed in this test rig with and without pitting. Results show combining the two measurement technologies improves the detection of pitting damage on spur gears.
User's manual for tooth contact analysis of face -milled spiral bevel gears with given machine-tool settings. Research was performed to develop a computer program that will: 1 simulate the meshing and bearing contact for face milled spiral beval gears with given machine tool settings; and 2 to obtain the output, some of the data is required for hydrodynamic analysis.
It is assumed that the machine tool settings and the blank data will be taken from the Gleason summaries. The difference between the computer programs developed herein and the other one is as follows: 1 the mean contact point of tooth surfaces for gears with given machine tool settings must be determined iteratively, while parameters H and V are changed H represents displacement along the pinion axis, V represents the gear displacement that is perpendicular to the plane drawn through the axes of the pinion and the gear of their initial positions , this means that when V differs from zero, the axis of the pionion and the gear are crossed but not intersected; 2 in addition to the regular output data transmission errors and bearing contact , the new computer program provides information about the contacting force for each contact point and the sliding and the so-called rolling velocity.
The following topics are covered: 1 instructions for the users as to how to insert the input data; 2 explanations regarding the output data; 3 numerical example; and 4 listing of the program. Precision Gear Industry,. Precision Gear Management Shortcomings within the U. Precision Gear Industry A new type of face-gear drive with intersected axes of rotation formed by a helical involute pinion and conjugated face-gear has been investigated.
Generation of face-gears by a shaper free of undercutting and pointing has been investigated. A new method of grinding or cutting of face-gears by a worm of special shape has been developed. A computerized design procedure has been developed to avoid undercutting and pointing by a shaper or by a generating worm.
Also, a method to determine the limitations of the helix angle magnitude has been developed. The method provides a localization of the bearing contact to reduce the shift of bearing contact caused by misalignment. The analytical method provides a simulation of the meshing and contact of misaligned gear drives.
An automatic mesh generation method has been developed and used to conduct a 3D contact stress analysis of several teeth. The theory developed is illustrated with several examples. Surface defect detection and dimension measurement of automotive bevel gears by manual inspection are costly, inefficient, low speed and low accuracy. In order to solve these problems, a synthetic bevel gear quality inspection system based on multi-camera vision technology is developed.
The system can detect surface defects and measure gear dimensions simultaneously. The system can detect knock damage, cracks, scratches, dents, gibbosity or repeated cutting of the spline, etc. The smallest detectable defect is 0. One inspection process takes no more than 1. Both precision and speed meet the requirements of real-time online inspection in bevel gear production. PubMed Central. Application of active control landing gear technology to the A aircraft. In the first concept, referred to as the alternate concept a servovalve in a closed pressure control loop configuration effectively varies the size of the third stage spool valve orifice which is embedded in the strut.
This action allows the internal energy in the strut to shunt hydraulic flow around the metering orifice. The command signal to the loop is reference strut pressure which is compared to the measured strut pressure, the difference being the loop error. Technology survey on video face tracking. With the pervasiveness of monitoring cameras installed in public areas, schools, hospitals, work places and homes, video analytics technologies for interpreting these video contents are becoming increasingly relevant to people's lives. Among such technologies , human face detection and tracking and face identification in many cases are particularly useful in various application scenarios.
While plenty of research has been conducted on face tracking and many promising approaches have been proposed, there are still significant challenges in recognizing and tracking people in videos with uncontrolled capturing conditions, largely due to pose and illumination variations, as well as occlusions and cluttered background. It is especially complex to track and identify multiple people simultaneously in real time due to the large amount of computation involved. In this paper, we present a survey on literature and software that are published or developed during recent years on the face tracking topic.
The survey covers the following topics: 1 mainstream and state-of-the-art face tracking methods, including features used to model the targets and metrics used for tracking; 2 face identification and face clustering from face sequences; and 3 software packages or demonstrations that are available for algorithm development or trial.
A number of publically available databases for face tracking are also introduced. The Three " Faces " of Technology Education. There are three " faces " of Technology Education. What is meant by this? It means that more emphasis should be given to the students who take industrial technology education ITE classes at the high school level with less emphasis given to standards, objectives, or outcomes developed by national organizations. Viewed in this light, three different…. Gear optimization.
The use of formal numerical optimization methods for the design of gears is investigated. To achieve this, computer codes were developed for the analysis of spur gears and spiral bevel gears. These codes calculate the life, dynamic load, bending strength, surface durability, gear weight and size, and various geometric parameters. It is necessary to calculate all such important responses because they all represent competing requirements in the design process. This code allows the user to define the optimization problem at the time of program execution.
Typical design variables include face width, number of teeth and diametral pitch. The user is free to choose any calculated response as the design objective to minimize or maximize and may impose lower and upper bounds on any calculated responses. Typical examples include life maximization with limits on dynamic load, stress, weight, etc. The research codes were written in modular form for easy expansion and so that they could be combined to create a multiple reduction optimization capability in future.
Abstract This study employed the Model of Technology Preference MTP to explain the relationship of the variables as the antecedents of behavioral intention to adopt a social networking site SNS for communication. Self-administered questionnaires were distributed to SNS account users using paper-based and web-based surveys that led to valid responses.
The data were analyzed using structural equation modeling SEM. The data support the hypotheses that perceived enjoyment and social presence are predictors of ATTP. SNS development should provide features that ensure enjoyment and social presence for users to communicate instead of using the traditional face-to-face method of communication. Face-to-face or not-to- face : A technology preference for communication.
This study employed the Model of Technology Preference MTP to explain the relationship of the variables as the antecedents of behavioral intention to adopt a social networking site SNS for communication. Naffin, Richard K. This report investigates the practical usage of hybrid structures for rotorcraft gearing. The primary driver for utilizing hybrid structures for rotorcraft gearing is to reduce the drive system weight. The hybrid structure concept featured in this study for rotorcraft gearing consists of a metallic gear tooth-rim, a web section manufactured from composite materials, and a metallic hub.
The metallic gear tooth-rim is manufactured from conventional gear steel alloys, such as AISI The gear tooth-rim attaches to the outer diameter of the web section made from composite materials. The inner diameter of the composite web can then attach to a metallic hub, completing the assembly. It is assumed that areas of the shafting or hub where rolling element bearings may ride must remain as gear steel alloys for this study. A new method for design and generation of spiral bevel gears of uniform tooth depth with localized bearing contact and low level of transmission errors is considered.
The main features of the proposed approach are as follows: 1 The localization of the bearing contact is achieved by the mismatch of the generating surfaces. The bearing contact may be provided in the longitudinal direction, or in the direction across the surface; and 2 The low level of transmission errors is achieved due to application of nonlinear relations between the motions of the gear and the gear head-cutter.
Such relations may be provided by application of a CNC machine. The generation of the pinion is based on application of linear relations between the motions of the tool and the pinion being generated. The relations described above permit a parabolic function of transmission errors to be obtained that is able to absorb almost linear functions caused by errors of gear alignment. A computer code has been written for the meshing and contact of the spiral bevel gears with the proposed geometry. The effect of misalignment on the proposed geometry has also been determined.
Numerical examples for illustration of the proposed theory have been provided. The main features of the proposed approach are as follows: 1 the localization of the bearing contact is achieved by the mismatch of the generating surfaces. The bearing contact may be provided in the longitudinal direction, or in the direction across the surface; and 2 the low level of transmission errors is achieved due to application of nonlinear relations between the motions of the gear and the gear head-cutter.
Aircraft engines of the future will require capability bearing compartment seals than found in current engines. Geared systems driving the fan will be subjected to inertia and gyroscopic forces resulting in extremely high angular and radial misalignments. Because of the high misalignment levels, compartment seals capable of accommodating angularities and eccentricities are required. Initial seal tests established the misalignment limits of the current technology circumferential seal.
From these results a more compliant seal configuration was conceived, designed, fabricated, and tested. Further improvements to the design are underway and plans are to conduct a durability test of the next phase configuration. A technical approach is presented, including design modification to a "baseline"seal, carbon grade selection, test rig configuration, test plan and results of analysis of seal testing. Hybrid Gear.
A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface hub and gear tooth rim is described. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design. This paper attempts to identify critical factors accounting for student choices, first, by investigating advanced learners' reported….
Wabble gear drive mechanism. The wabble gear principle was applied in the design of a driving mechanism for controlling spacecraft solar panels. The moving elements, other than the output gear , are contained within a hermetically sealed package to prevent escape of lubricants and ingestion of contaminant particles. The driving gear contains one more tooth than the output gear on a concave, conical pitch surface of slightly larger apex angle.
The two gears mesh face to face such that engagement takes place at one point along the circumference. The driving gear is not permitted to rotate by virtue of its attachment through the bellows which permits flexure in the pitch and yaw position, but not in roll. As the bearing carrier rotates, the inclined mounting of the bearing causes the driving gear to perform a wabbling, irrotational motion.
This wabbling motion causes the contact point between the output gear and the driving gear to traverse around the circumference of the gears once per revolution of the bearing carrier. This study identified the problem solving strategies used by students within a university course designed to teach pre-service teachers educational technology , and whether those strategies were influenced by the format of the course i.
It also examined to what extent the type of problem solving strategies…. On-Line vs. This paper investigates students' assessment of on-line vs face-to-face delivery of lecture-based information technology courses. The study used end-of-course surveys to examine students' ratings of five course quality indicators: Course Organization, Assessment and Grading Procedures, Instructor Performance, Positive Learning Experience, and…. In Wicklein conducted a study to determine the present and the future critical issues and problems facing the technology education TE profession.
The Wicklein study questioned 25 panelists from 15 states and the District of Columbia to ascertain the issues and problems facing TE. However, in the Wicklein study, only seven of the panelists…. Faces of the Recovery Act: Technologies. The technology education in Taiwan is prescribed in the national curriculum and provided to all students in grades However, it faces the following challenges: 1 Lack of worthy image, 2 Inadequate teachers in elementary schools, 3 Deficient teaching vitality in secondary schools, and 4 Diluted technology teacher education programs.
The purpose of this article is to describe the characteristics and experiences of individuals who use technology to support telephone or face-to-face communication after total laryngectomy. An online questionnaire was used to identify potential participants. Seventeen individuals met inclusion criteria and participated in an in-depth survey. They were compared with a reference group matched for age, gender, and time postsurgery who did not use these technologies.
Open-ended responses were summarized. Compared with the matched reference group, individuals who used technology to support verbal communication had undergone more aggressive cancer treatment and used more communication methods. They were less likely to use an alaryngeal speech method, had greater difficulty over the telephone, and used more repair strategies in face-to-face communication. The 2 groups did not differ significantly in the frequency or success of their communication, however. Open-ended responses revealed great variety with regard to their reasons, purposes, and timing of technology use.
There is a subset of individuals using technology to support verbal communication very successfully after laryngectomy. Usage was not limited to those who were unable to communicate verbally and often continued long after the initial postoperative period in many settings, for various purposes, and in combination with other methods of communication. Adolescents' technology and face-to-face time use predict objective sleep outcomes. The present study examined both within- and between-person associations between adolescents' time use technology -based activities and face-to-face interactions with friends and family and sleep behaviors.
We also assessed whether age moderated associations between adolescents' time use with friends and family and sleep. Adolescents wore an actigraph monitor and completed brief evening surveys daily for 3 consecutive days. We assessed 8 technology -based activities eg, texting, working on a computer , as well as time spent engaged in face-to-face interactions with friends and family, via questions on adolescents' evening surveys. Actigraph monitors assessed 3 sleep behaviors: sleep latency, sleep hours, and sleep efficiency.
Hierarchical linear models indicated that texting and working on the computer were associated with shorter sleep, whereas time spent talking on the phone predicted longer sleep. Time spent with friends predicted shorter sleep latencies, while family time predicted longer sleep latencies. Age moderated the association between time spent with friends and sleep efficiency, as well as between family time and sleep efficiency. Specifically, longer time spent interacting with friends was associated with higher sleep efficiency but only among younger adolescents.
Furthermore, longer family time was associated with higher sleep efficiency but only for older adolescents. Findings are discussed in terms of the importance of regulating adolescents' technology use and improving opportunities for face-to-face interactions with friends, particularly for younger adolescents. Published by Elsevier Inc. Summary of NASA landing- gear research. This paper presents a brief summary of the airplane landing gear research underway at NASA.
This paper deals mainly with the programs on tire-tread materials, powered wheel taxiing, air cushion landing systems, and crosswind landing gear research with particular emphasis on previously unreported results of recently completed flight tests. Work in the remaining areas is only mentioned. A novel safety device with metal counter meshing gears discriminator directly driven by axial flux permanent magnet micromotors based on MEMS technology. Each group of counter meshing gears is onepiece and driven directly by an axial flux permanent magnet micromotor respectively.
The energy-coupling element is an optical shutter with two collimators and a coupler wheel. It is fabricated by combination of an LiGA-like process and precision mechanical engineering. The device has simple structure, few dynamic problems, high strength and strong reliability. Activating social strategies: Face-to-face interaction in technology -mediated citizen science. The use of crowds in research activities by public and private organizations is growing under different forms. Citizen science is a popular means of engaging the general public in research activities led by professional scientists.
By involving a large number of amateur scientists, citizen science enables distributed data collection and analysis on a scale that would be otherwise difficult and costly to achieve. While advancements in information technology in the past few decades have fostered the growth of citizen science through online participation, several projects continue to fail due to limited participation. Such web-based projects may isolate the citizen scientists from the researchers. By adopting the perspective of social strategy, we investigate within a measure-manipulate-measure experiment if motivations to participate in a citizen science project can be positively influenced by a face-to-face interaction with the scientists leading the project.
Such an interaction provides the participants with the possibility of asking questions on the spot and obtaining a detailed explanation of the citizen science project, its scientific merit, and environmental relevance. Social and cultural factors that moderate the effect brought about by face-to-face interactions on the motivations are also dissected and analyzed. Our findings provide an exploratory insight into a means for motivating crowds to participate in online environmental monitoring projects, also offering possible selection criteria of target audience.
Gear Performance Improved by Coating. Tests were run using either a pair of uncoated gears or a pair of coated gears coated gears mated with uncoated gears were not evaluated. The fatigue test results, shown on Weibull coordinates in the graph, demonstrate that the coating provided substantially longer fatigue lives even though some of the coated gears endured larger stresses. The increase in fatigue life was a factor of about 5 and the statistical confidence for the improvement is high greater than 99 percent. Examination of the tested gears revealed substantial reductions of total wear for coated gears in comparison to uncoated gears.
The coated gear surface topography changed with running, with localized areas of the tooth surface becoming smoother with running. Theories explaining how coatings can extend gear fatigue lives are research topics for coating, tribology, and fatigue specialists. Experimental technologies comparison for strain measurement of a composite main landing gear bay specimen. The development of advanced monitoring system for strain measurements on aeronautical components remain an important target both when related to the optimization of the lead-time and cost for part validation, allowing earlier entry into service, and when related to the implementation of advanced health monitoring systems dedicated to the in-service parameters verification and early stage detection of structural problems.
The paper deals with the experimental testing of a composite samples set of the main landing gear bay for a CS category aircraft, realized through an innovative design and production process. The test have represented a good opportunity for direct comparison of different strain measurement techniques: Strain Gauges SG and Fibers Bragg Grating FBG have been used as well as non-contact techniques, specifically the Digital Image Correlation DIC and Infrared IR thermography applied where possible in order to highlight possible hot-spot during the tests. The crucial points identification on the specimens has been supported by means of advanced finite element simulations, aimed to assessment of the structural strength and deformation as well as to ensure the best performance and the global safety of the whole experimental campaign.
From discard ban to exemption: How can gear technology help reduce catches of undersized Nephrops and hake in the Bay of Biscay trawling fleet? The fleet records historically high levels of discard despite numerous gear selectivity studies. Together with high discards survival, new technological solutions to minimize catches of undersized individuals could justify local exemptions from the discard ban.
Our study focuses on the effects of two selective devices, a square mesh cylinder SMC and a grid, on the escapement of undersized individuals and discard reduction. Relative catch probability of the modified gear compared with the traditional gear was modelled using the catch comparison method. Potential losses from the commercial fraction of the catch were taken into account to assess their influence on the economic viability of fishing with the modified gears.
The two devices had similar effects on undersized Nephrops escapement and on discard reduction, with median values of Only the grid was efficient for undersized hake, recording median values of escapement and discard reduction equal to Some loss from the commercial fraction of the catch was to be expected with both devices, which could be compensated for in the long term by the contribution of undersized individuals to the stock biomass. Our results support the use of selective gears technology as part of an integrated framework including control and management measures to mitigate the effect of the discard ban both for fishers and for the ecosystem.
Further work is needed to quantify the effect of additional escapement from the gear on stock dynamics. Efficiency of nonstandard and high contact ratio involute spur gears. A power loss prediction was extended to include involute spur gears of nonstandard proportions. The method is used to analyze the effects of modified addendum, tooth thickness, and gear center distance in addition to the parameters previously considered which included gear diameter, pitch, pressure angle, face width, oil viscosity, speed, and torque. Particular emphasis was placed on high contact ratio gearing contact ratios greater than two.
Despite their higher sliding velocities, high contact ratio gears are designed to levels of efficiency comparable to those of conventional gears while retaining their advantages through proper selection of gear geometry. Detail view of drum screen short shaft gears , journal Detail view of drum screen short shaft gears , journal bearing, rotation drive chain, upper sprocket gear , and drum screen edge in background, facing southeast downstream from drum screen cover.see
nypowoqevuki.tk: I. Novikov - Engineering & Transportation: Books
The development of new types of planetary and planetary face-gear drives is proposed. The new designs are based on regulating backlash between the gears and modifying the tooth surfaces to improve the design. The goal of this work is to obtain a nearly uniform distribution of load between the planet gears. In addition, a new type of planetary face-gear drive was developed in this project. The development of highly reliable health-monitoring systems is one technology area recommended for reducing the number of helicopter accidents. Helicopter transmission diagnostics are an important part of a helicopter health-monitoring system because helicopters depend on the power train for propulsion, lift, and flight maneuvering.
One technique currently being tested for increasing the reliability and decreasing the false alarm rate of current transmission diagnostic tools is the replacement of simple single-sensor limits with multisensor systems integrating different measurement technologies. Improving applied roughness measurement of involute helical gears. With improving gear design and manufacturing technology , improvement in metrology is necessary to provide reliable feedback to the designer and manufacturer.
A recommended gear roughness measurement method is applied to a micropitting contact fatigue test gear. The development of wear and micropitting is reliably characterised at the sub-micron roughness level. Changes to the features of the localised surface texture are revealed and are related to key gear meshing positions. The application of the recommended methodology is shown to provide informative feedback to the gear designer in reference to the fundamental gear coordinate system, which is used in gear performance simulations such as tooth contact analysis.
Technology offers various tools of improving the teaching -- learning process. It revolutionizes teaching from traditional face-to-face to distance and online learning. This study described and compared the performance of BSE II students in educational technology using the traditional face-to-face classroom interaction and the blended learning…. NASA gear research and its probable effect on rotorcraft transmission design.
The results of the NASA gear research is reviewed as well as those programs which are presently being undertaken. Research programs studying pitting fatigue, gear steels and processing, life prediction methods, gear design and dynamics, elastohydrodynamic lubrication, lubrication methods and gear noise are presented. The impact of advanced gear research technology on rotorcraft transmission design is discussed.
Load sharing behavior is very important for power-split gearing system, star gearing reducer as a new type and special transmission system can be used in many industry fields. However, there is few literature regarding the key multiple-split load sharing issue in main gearbox used in new type geared turbofan engine. Further mechanism analysis are made on load sharing behavior among star gears of star gearing reducer for geared turbofan engine.
Comprehensive meshing error analysis are conducted on eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of star gearing reducer respectively. Floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of sun gear and annular gear are taken into account.
A refined mathematical model for load sharing coefficient calculation is established in consideration of different meshing stiffness and supporting stiffness for components. The regular curves of load sharing coefficient under the influence of interactions, single action and single variation of various component errors are obtained.
The accurate sensitivity of load sharing coefficient toward different errors is mastered. The load sharing coefficient of star gearing reducer is 1. This paper provides scientific theory evidences for optimal parameter design and proper tolerance distribution in advanced development and manufacturing process, so as to achieve optimal effects in economy and technology.
Volume 3. Roller Gear Manufacture. It is in the free- wheel mode when the main rotor shaft tends to turn faster than the Check face runout on each end of largo gears. Not to exceed. Even with recent advances in psychological treatments and mobile technology , online computerized therapy is not yet popular. College students, with ubiquitous access to technology , experiencing high distress, and often nontreatment seekers, could be an important area for online treatment dissemination. Finding ways to reach out to college students by offering psychological interventions through technology , devices, and applications they often use, might increase their engagement in treatment.
This study evaluates college students' reported willingness to seek help for emotional distress through novel delivery mediums, to play computer games for learning emotional coping skills, and to disclose personal information online. We also evaluated the role of ethnicity and level of emotional distress in help-seeking patterns. A survey exploring our domains of interest and the Mental Health Inventory [MHI] as mental health index were completed by students mean age More participants expressed preference for online versus face-to-face professional help.
We found no relationship between MHI and help-seeking preference. A third of participants were likely to disclose at least as much information online as face-to-face. Ownership of mobile technology was pervasive. Asian Americans were more likely to be nontreatment seekers than Caucasians. Most participants were interested in serious games for emotional distress. Our results suggest that college students are very open to creative ways of receiving emotional help such as playing games and seeking emotional help online, suggesting a need for online evidence-based treatments.
This article shows that technological neutrality, determinism, and autonomy correspond to parts of a spectrum of possible historical relations between societies and their technologies. The spectrum of relations is based on the recognition that as we change technology , technology simultaneously changes us.
This reinterpretation compels us to face…. Design of aircraft turbine fan drive gear transmission system. The following basic types of gear reduction concepts were studied as being feasible power train systems for a low-bypass-ratio, single-spool, geared turbofan engine for general aircraft use: 1 single-stage external-internal reduction, 2 gears offset shafting , 3 multiple compound idler gear system concentric shafting , and 4 star gear planetary system with internal ring gear final output member concentric shafting-counterrotation.
In addition, studies were made of taking the accessories drive power off both the high-speed and low-speed shafting, using either face gears or spiral bevel gears. Both antifriction and sleeve-type bearings were considered for the external-internal and star-planet reduction concepts. The purpose of this research project was to examine the effectiveness of supervised literacy tutoring delivered by 25 secondary teacher candidates to middle and high school students via webcam technology and in person.
The results stem from two semester-long studies of technology -delivered tutoring from a university to middle and high school…. National standards and funds have helped ensure that technology access is no longer as problematic as it once was in education, but some questions remain about how effectively educational technologies are being utilized prepare students with 21st century skills that include higher-order thinking skills.
For this reason, scholars have emphasized…. A review of recent progress for the analysis of spiral bevel gears will be described. Hypoid gear dimensions were tooth number 4 and 39 of driver and follower respectively, pinion offset 15mm, carbonized heat treatment. Maximum temperature rise of grease lubrication was Temperature rise ratio of grease to hypoid gear oil was nearly 1. Right angle hypoid-helical gear motors of rating 0. Sliding resistance in gear teeth can have a dominant effect on housing vibration, noise and efficiency.
One of the parameters that greatly influence the friction under certain running conditions is surface roughness.
- Russian school of the theory and geometry of gearing: Its origin and golden period ( )!
- Spiritual Maturity: Preserving Congregational Health and Balance (Prisms)?
- The Philosophy of Dionysius the Areopagite (Philosophia Antiqua).
- Urban hydrology for small watersheds.
In this work, rough friction was measured in lubricated sliding of roller surfaces. By examining 3D surface topography of two mating bodies, both surface roughness and its interaction between contacts were studied. For this purpose, a rough-friction test rig was designed and constructed. In this rig the contact pressure between two rollers can be varied while controlling the sliding speed. Rollers that were manufactured to simulate the real gear surfaces were examined by a 3D stylus profilometer resolution 4 nm.
The results showed good agreement with current theory. Friction and wear of transmission interface are key ways of energy consumption and transmission mechanism failure. Economic losses caused by friction and wear of transmission interface are astonishing.
- Companion Encyclopedia of Theology.
- Essentials of Pediatric Radiology: A Multimodality Approach;
- Learning Gear Essentials from Dudley's Handbook.
- Algebra: Volume I: Fields and Galois Theory.
- Novikov gearing: Achievements and ways to further development!
- Theory and Practice of Gearing and Transmissions In Honor of Professor Faydor L. Litvin;
Gear transmission is the most common mechanism of power and motion transfer. Improvement of antiwear and friction-reducing capacities of gear surface has therefore become one of the most interested research topics in tribological cycle. In recent years, in our studies of interdisciplinary transmission tribology and transmission tribology design, a new idea of on-line strengthening of gear surface has been proposed, some achievements have also been made.
Generally speaking, the author obtained that, the higher the lubricating oil viscosity, the lower the friction loss. Further he found that a most suitable oil viscosity in order to reduce the friction loss exists for the gear unit, including not only the test gears but also the bearings and the gear box. The plastic gear is used for turn and power transmission. The abrasion and damage of the tooth of plastic gears has become a problem. In addition, in the use of the plastic gear, it is the problem of strength evaluation of teeth. There is two thinks on the strength of the tooth.
It is a breakage with the progress of the abrasion of the tooth in other. This paper deals with the result of tooth damage in evaluation of a molded plastic gear. Injury to a tooth is classified largely in two groups, one is progress damage and other is final damage. The abrasion of the tooth was considered as following. The relationship between stress of Hertzian contact, circumference speed of the tooth, running time and abrasion weight was clarified.
It was possible to obtain the precious material for design and use of molded plastic gear from the result in this study. The plastic gears, made of the low fractional materials or emploied the grease, break by the bending stress. Since the larger bending deflection with transmitted power the larger real contact ratios of plastic gears, the bending stress calculation formulae of the metalic gears don't be able to apply for the plastic gears.
As the studies of the Prof.
The plastic gear is effective from the viewpoint of the productivity for the comparatively small gear. Generally, the plastic gear is made by the injection molding of the crystal resin.
In the case of the injection molding plastic gear, the deformed layer nearby the surface of tooth is softer than the core structure. Authors noticed that the sound level of the two plastic gears engaged was low while a skin layer and an intermediate one existed. It is expected that the noise level is kept low by positively forming deformed layer with some extent thickness. In this paper, the formation mechanism of the deformed layer in the injection molding plastic gear is studied.
FEM is used to perform the thermal analysis of the cooling process of the resin filled in the mold. According to the analytical results, the cooling rate of melting polymer of the near-wall region as well as the case of the product of metal amorphous alloy was very rapid. The relationship between the manufacturing conditions and the deformed layer for the injection molding gear was estimated.
In this study, we investigated the properties of noise and vibration for a pair of gears engaged a nylon gear with a steel gear. On the basis of experimental results, we considered about the noise generation mechanism. It becomes clear as follows. The plastic gear is excited vibration heavily and the noise is radiated loudly from the plastic gear rather than the mating steel gear.
The vibration of plastic gear is caused by the flexibleness of plastic gear tooth and the lateral vibration of plastic gear influences the noise radiation directly. It is considered that one of the practical ways to reduce the noise of plastic gear is to reduce the noise radiation from the plastic gears by decrease in lateral vibration. Exact analytical solutions of transmission errors with eccentricities of involute cylindrical gears are proposed.
Analytical equations to obtain transmission errors with eccentricities are derived shortly. The influence of the center distance errors, the ratio of eccentricities and phase differences is investigated under no load. In addition, transmission errors including eccentricities of a pair of spur gear are measured under no loading condition. The results show that the measured and calculated transmission errors agree with each other and the analysis is verified accurately.
The influence of center distance errors is so little as to be neglected comparing to the amount of transmission errors. The sum of eccentricities is related to the peak-to-valley value of transmission errors and the ratio of eccentricities is related to waveforms of transmission error curves. Phase difference of eccentricities has a little influence on transmission errors, but it is not negligible comparing to the amount of transmission error caused by tooth flank topography and tooth deflections.
For further applications, the analysis can be used to remove waviness from transmission error curves as the filtering technique. A scanning measurement of face milled, face hobbed, formate or generate hypoid gear is developed, and the concept of conjugate surface and composite error used in the measurement is introduced. A method of simulating tooth contact pattern and transmission error of hypoid gears based upon machine setting and actual tooth surface measurement data is discussed.
The result of the simulation is compared with the experimental data, and the effectiveness of the measurement of tooth flank form of hypoid gears is discussed in a case of wear trouble experienced actual mass production gears. A reference tooth flank has been used in the previous interferometry measurement of form deviation of gear tooth flank. In this investigation, new measuring method by an accurately ground plate instead of the reference tooth flank is proposed. The use of this reference plate incorporated makes cost, time and labour of manufacture of the reference tooth flank decrease.
This program has grown to include virtually all things automotive. One of the fastest growing areas of automotive research at SwRI is in transmission design. Great advances have been made in automotive transmission design, yet there is still much room for improvement. The current production, multi speed manual transmission, used in automotive applications represents a very mature technology.
A typical transmission consists of a dual shaft configuration, containing five pairs of gears in rotating contact with each other through which various load paths are selected. Supporting this system is a multiplicity of bearing sizes, types and locations. The challenge to the transmission designer is to provide a system that can provide high efficiency across a wide range of operating speeds and torque, under continually changing conditions.
High Conformal Gearing
Yet based upon dynamometer test results, efficiency values for transmissions used in similar sized vehicles, but produced by different manufacturers, have been found to vary greatly. This paper will provide efficiency trends and values associated with current production manual transmissions and how they are affected by mounting angle and operating temperatures. Areas in which improvements to efficiency can be realized will be discussed including lubrication, windage, bearings, supports, and gear tooth modifications.
This paper is identifying tendencies of future development of the gears and of general use and special geared transmissions. Tendencies are estimated on the basis of top research ideas, tendencies of technology and "state of the art" achievements in companies specialised in mechanical transmissions.
At cylindrical gears : technological method application for fitting within the ME class [DIN] of the admissible stress diagrams ; topological corrections, high toothing gears with integer contact ratio, re-launching non-involute gears in the new technological background offered by the possibility of grinding and checking any profiles. At worm gears : numerically controlled contact localising using optimising parameters, double-enveloping worm gears with grindable worm by means of an internal mobility procedure.
Also the paper identifies possible development tendencies of gear transmissions : general use speed reducers, custom-made gearboxes for power plants, mining, ships, cement industry , special multipliers, geared motors, variable speed transmissions, drives for robots and machine tools. This means the accuracy of tooth profile most greatly affects gear performance among all of the gear items. This paper describes the change of gear measuring instruments in the world, from mechanical type to CNC type machine.
Aiming at the high-speed and high accurate measurement, ultimate measuring method such as "free from the influence of room temperature", "rough centering" and "output of measured deviation based on the gear functional center axis" are proposed. This small book contains eight chapters, which set forth the chronological development of gearing. Dudley recreates before readers a bright picture of the development of gearing from ancient till modem times.
This is helped by carefully selected illustrations. Travelling through the ages a reader learns that the Egyptians and Babylonians were using gears in clocks and water-lifting equipment.
The Romans, Greeks and Arabians made wide use of gearing in astronomical devices, in flour-mill drives and even in speed indicating devices. One finds with amazement, that in Roman Empire times gears were used consisting both of bevel and of worm and pinion pairs, and also for transmission of intermittent motion. The most ancient mechanism created in China about B.
A complex differential gear is the basis of this device. Very interesting information about the historical changes of tooth form, from wooden pin to involute, is presented, and great attention is paid to the development of toothcutting methods. The author adduces only brief information about the scientists who developed the foundations of the theory of gear tooth action, and their writings.
Novikov gearing: Achievements and ways to further development
Unfortunately one does not find here the names of French scientist T. Olivier and Russian scientist H. The elaboration of geometrical methods of conjugate gear generation is to the merit of Olivier, while Gochman worked out the fundamental analytical theory of gearing in three dimensions. The last two chapters describe the development of gearing in the twentieth century.
Related Novikov Gearing: Achievements and Development
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