Download or read book An Experimental Study on the Scuffing Performance of High power Spur Gears at Elevated Oil Temperatures written by James Walter Brenneman and published by . This book was released on 2013 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this study, a number of spur gear tests were performed under high-power and high-temperature conditions representative of certain aerospace gearing applications. As the first type of tests, long cycle tests of 100 million cycles were performed at set operating speed, load, and temperature conditions. The second type of tests, load-staged scuffing tests, implemented an incrementally increased torque schedule under constant speed and oil temperature conditions. Two different gear tooth surfaces were considered in these tests: hard ground surfaces representative of rough, as machined gear surfaces and chemically polished gear surfaces that were an order of magnitude smoother than the ground surfaces. The primary failure mode of concern was scuffing of the contact surfaces due to temperature build up. The impact of surface roughness amplitudes, contact stress, and oil inlet temperature on scuffing failures were investigated. Effects of ramp up procedures for the speed and torque, as well as the introduction of a break-in test stage were also investigated to show that they are critical to the scuffing performance of gears.
Download or read book An Experimental Study of Scuffing Performance of a Helical Gear Pair Subjected to Different Lubrication Methods written by Rohit Matthew Abraham and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Lubrication systems used in gear trains are intended to serve two distinct purposes: (i) provide the quantities of oil to gear mesh contact interfaces to allow formation of a healthy elastohydrodynamic fluid film and (ii) help remove heat generated at gear mesh contact interfaces. Failure of the lubrication system in either of these tasks often results in a temperature induced contact failure, called scuffing. This study investigates the effectiveness of various lubrication methods in preventing scuffing. A new high-speed gear test set-up is developed specifically for investigating the scuffing performance of high-speed, high-load helical gears operating at realistic oil temperature conditions. The objective of this study is to experimentally characterize the scuffing performance of the helical gears as a function of various lubrication methods and parameters defining each method. Sets of scuffing experiments are performed using the test methodology developed and lubrication methods that successfully prevented scuffing of the gears are identified. The test matrix includes two different automotive drivetrain lubricants and different lubrication methods of forced (jet) lubrication, dip lubrication and mist lubrication. The test specimens consist of gears having three surface finishes, (i) ground-honed gears which were identified as the baseline, (ii) super-finished gears and (iii) phosphate coated gears. The effects of parameters such as jet flow rate, jet velocity and impingement depth on scuffing are investigated and tabulated using the results from the jet lubricated tests. The impact of gear micro-geometry and edge-loading effects on scuffing initiation are also investigated.
Download or read book An Experimental Study on the Effects of Debris Damage on Scuffing Performance of Spur Gear Pairs written by Tiffany Wen Roe Lim and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, a test methodology was developed to induce debris to the gear tooth profiles during the operation of a gear pair. This methodology was applied to a number of spur gear specimens for different types, quantities and sizes of debris particles. The extent of surface damage due to application of debris was documented and related to the sizes, types and quantities of debris applied. A high-speed and high-temperature test machine was used to put gears with varying severity of debris damage through a staged scuffing test to investigate the influence of such damage on scuffing outcome. While selected damage sites monitored during staged scuffing tests did not exhibit any progression to be identified as initiation sites for scuffing failure, gears with no or little debris damage were shown to pass the scuffing test while gears with heavier debris damage scuffed consistently. As such, the results of this study show conclusively that there is a direct correlation between severity of the debris damage and resultant scuffing performance of the gears.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983 with total page 1252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Impact of Engineered Surface Processes on Efficiency of Spur Gears written by Kreteeka Chaudhury and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study was conducted to evaluate the effect of surface finish on spur gear power losses under jet lubrication. Four different surface finish combinations were tested: (i) hard ground surface pair, (ii) chemically polished surface pair, (iii) super honed surface pair and (iv) hard ground against chemically polished surface pair. The test was conducted at 432 different operating condition combinations of speed, torque, lubricant type and inlet temperature. An FZG back-to-back set up was used to conduct the test. Surface roughness inspections were carried out at regular intervals to monitor any changes in surface roughness characteristics. The measured power losses were resolved into spin (load independent) and mechanical (load dependent) power losses. The relation between both losses and various operating conditions were explored. As expected, spin power loss did not vary with variation in surface finish. Mechanical power loss increased with increase in speed and torque. Various surface roughness and operating parameters such as BAC curves and lambda ratio were calculated for each surface finish combination to study their correlation to power losses measured. For smoother surfaces, an increase in temperature decreased power loss as the viscosity of the lubricant decreased and hence rolling friction losses dominating the mechanical power loss decreased. However, for rougher surfaces sliding friction losses seemed to be dominant due to high amounts of asperity contact. Thus, more cases of higher power loss at high temperatures were observed for rougher surfaces.
Download or read book The Influence of a Class of Surface Defects on the High speed Scuffing Performance of Spur Gears written by Gunther Shepard Beall and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gear teeth experience contact conditions that vary continuously as they pass through the meshing zone. Thus, not only the sizes but also the positions of surface defects become critical to their scuffing survivability. High-speed gearbox cost and reliability can be improved by quantifying these features and determining their impact on scuffing performance. Pursuant to this, representative defects in the form of scratches are applied in two batches to the contacting surfaces of high-quality spur gear specimens. These, along with an undamaged baseline gear pair, are then tested through a staged scuffing matrix incrementally increasing the operating load, speed, and lubricant temperature. Metrological procedures developed to quantify scratch parameters and track surface damage are used initially and throughout testing to document evolvement of the surfaces. It is concluded that (i) larger scratches generally decrease scuffing performance, (ii) the location of scratches is critical to scuffing performance; scuffing was never observed in areas where sliding velocities were low, (iii) increased wear and heat generation are observed on defects in high-sliding regions, and (iv) wear and tribo-film formation improve the scuffing performance of scratched gears. In addition, thermal elastohydrodynamic lubrication simulations are performed to confirm that increasing scratch width and surface sliding velocities have the most influence on increasing the lubricant flash temperatures.
Download or read book Experimental Investigation of Spur Gear Efficiency written by Travis T. Petry-Johnson and published by . This book was released on 2007 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: An experimental investigation of high-speed spur gear efficiency was conducted for both jet-lubricated, dry sump conditions and dip-lubricated conditions. Inspection methodologies were developed for the documentation of gear surface roughness and wear after each test. An experimental test matrix including gears of two different modules and surface roughness levels operating under jet-lubrication conditions with four different gear lubricants was developed to quantify the influence of these parameters on load- dependent (mechanical) and load-independent (spin) power losses. The spur gear efficiency test machine was modified for dip-lubricated load independent power loss measurements, allowing direct comparison to jet-lubricated conditions using the same test fixtures. An experimental test matrix including unity ratio gears of different module and face width operating in an oil bath of four different levels for a range of rotational speed and oil viscosity was developed. The influence of rotational speed, oil viscosity, oil bath level, and rotational direction on load independent power loss was quantified.
Download or read book High Conformal Gearing written by Stephen P. Radzevich and published by CRC Press. This book was released on 2016-01-05 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a Concept That Makes Gear Transmissions Noiseless, Smaller, and Lighter in WeightHigh-conformal gearing is a new gear system inspired by the human skeleton. Unlike conventional external involute gearing, which features convex-to-convex contact, high-conformal gearing features a convex-to-concave type of contact between the tooth fla
Download or read book Experimental Investigation of Spur Gear Efficiency and the Development of a Helical Gear Efficiency Test Machine written by Michael Daniel Moorhead and published by . This book was released on 2007 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Gear and transmission efficiency is one of the major issues in the automotive and aerospace industries. Both fuel economy and emission characteristics of vehicles are influenced by the efficiency of the drive trains and transmissions. The literature on gear efficiency is limited to few models. Accuracy of these models was not demonstrated, mainly due to the lack of experimental data, especially under high-speed conditions. Recent experiments by Chase [1] and Petry-Johnson [2] provided an extensive set of experimental data on efficiency for unity-ratio, precision spur gears operating at high- power conditions, representing racing applications. This experimental database was instrumental in validating the efficiency model of Xu, et al [3] for spur gears. This study presents experiments with the aim of extending this jet-lubricated spur gear efficiency database to non-unity ratio, production quality gear pairs having various surface treatments and operating with different lubricants under typical passenger vehicle conditions. As a separate study, it also provides a complete spin loss database for unity-ratio gears operating under dip-lubricated conditions. Direct comparisons between the two lubrication methods are also presented. Lastly, details of a design study for development of a test machine for efficiency measurements for helical gears is presented.
Download or read book Proceedings of China SAE Congress 2019 Selected Papers written by China Society of Automotive Engineers and published by Springer Nature. This book was released on 2020-11-04 with total page 1109 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings gather outstanding papers presented at the China SAE Congress 2019. Featuring contributions mainly from China, the biggest carmaker as well as most dynamic car market in the world, the book covers a wide range of automotive topics and the latest technical advances in the industry. Many of the approaches included can help technicians to solve practical problems that affect their daily work. In addition, the book offers valuable technical support to engineers, researchers and postgraduate students in the field of automotive engineering.
Download or read book Nanolubricants written by Jean Michel Martin and published by John Wiley & Sons. This book was released on 2008-04-30 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technology involved in lubrication by nanoparticles is a rapidly developing scientific area and one that has been watched with interest for the past ten years. Nanolubrication offers a solution to many problems associated with traditional lubricants that contain sulphur and phosphorus; and though for some time the production of nanoparticles was restricted by the technologies available, today synthesis methods have been improved to such a level that it is possible to produce large quantities relatively cheaply and efficiently. Nanolubricants develops a new concept of lubrication, based on these nanoparticles, and along with the authors’ own research it synthesises the information available on the topic of nanolubrication from existing literature and presents it in a concise form. Describes the many advantages and potential applications of nanotechnology in the tribological field. Offers a full review of the state-of-the-art as well as much original research that is yet unpublished. Includes sections on boundary lubrication by colloïdal systems, nanolubricants made of metal dichalcogenides, carbon-based nanolubricants, overbased detergent salts, nanolubricants made of metals and boron-based solid nanolubricants and lubrication additives. Authored by highly regarded experts in the field with contributions from leading international academics. Nanolubricants will appeal to postgraduate students, academics and researchers in mechanical engineering, chemical engineering and materials science. It should also be of interest to practising engineers with petroleum companies and mechanical manufacturers.
Download or read book Development of an Experimental Methodology for Evaluation of Gear Contact Fatigue Under High power and High temperature Conditions written by Nicholas Leque and published by . This book was released on 2011 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Contact fatigue failures in the form of pitting or micro-pitting have been a perennial problem in power transmission applications. These failures are dictated by a large number of parameters including loading conditions, gear geometry and tooth modifications, kinematics (rolling and sliding velocities), lubricant parameters (viscosity, pressure-viscosity behavior), and material parameters (material type, hardness, case depth, residual stresses). As such, theoretical treatment of contact fatigue failures has been rather challenging, directing the focus to the experimental investigation of the problem. Most of the experimental gear pitting studies to date were limited to low-speed and low-temperature operating conditions. This study aims at developing a methodology for evaluating the contact fatigue lives of gears under high-speed (pitch-line velocities up to 50 m/s), high-stress (contact stresses up to 2 GPa) and high-temperature (oil inlet temperatures up to 150C). Specifications of a test machine concept that meets these requirements are defined and two test machines are designed and procured for this purpose. Gear test specimens that result in pits consistently are developed with the other competing failures (wear, scuffing, tooth breakage), as well as the high vibration conditions, avoided. Preliminary high-speed tests are presented at the end, representing both automotive and aerospace conditions to show that pitting and micro-pitting failures can be produced with the proposed methodology.
Download or read book NASA Technical Paper written by and published by . This book was released on 1986 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Abstracts written by British Ship Research Association and published by . This book was released on 1965 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: Consists largely of abstracts of articles and papers of interest to shipbuilders, ship owners and marine engineers.
Download or read book Engineering written by and published by . This book was released on 1980 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation of High contact ratio Spur Gears with Profile Modification written by Dennis P. Townsend and published by . This book was released on 1979 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Lubrication Starvation on Flash Temperature for Thermal Mixed Elastohydrodynamic Gear Contacts written by Danielle D. Massé and published by . This book was released on 2019 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lubrication is provided to the gear trains in automotive and aerospace transmission systems to prevent mechanical contact through the formation of a full lubricant film, which in turn removes heat generated at the gear contact surfaces. When debris blocks the inlet nozzle, the flow of lubricant is restricted and mechanical components experience lubrication starvation. Under starved lubrication the temperatures of the contact surfaces become elevated which can lead to the formation of a weld between them, a catastrophic failure mode called scuffing. For spur gears, the occurrence of scuffing is due to high sliding in the vicinity of the root or tip, where the shear thinning effect decreases the lubrication film thickness. This lubricant depletion increases the contact pressure and frictional heat flux beyond a critical limit, resulting in weld formation. The weld is immediately torn apart by the continuous relative motion of the components, causing extreme damage to the tooth surfaces. The objective of this study is to characterize the tribological behavior of high sliding gear contacts under starved lubrication. This is achieved through numerical flow simulations which utilize a generalized Reynolds equation with a non-Newtonian flow coefficient, and incorporate the dependence of lubricant viscosity on pressure and temperature. In order to study the effects of lubrication starvation a film fraction parameter is used in the Reynolds equation, removing the need for measured or assumed inlet lubrication geometry. This work presents a parametric study of engineering surface profiles under different operating conditions to show an asymptotic relationship between flash temperature and the severity of the lubrication starvation, supported by an analysis of pressure, film fraction parameter, friction coefficient, and power loss. The results of these investigations justify further numerical and experimental studies of scuffing failure for gear contacts.
