人人文库网 > 图纸下载 > 毕业设计 > 发展中的新一代轮轴流动性：第一部分—测量轮轴齿轮润滑油耐久力和温度减少量装置的试验方法外文文献翻译、中英文翻译
发展中的新一代轮轴流动性：第一部分—测量轮轴齿轮润滑油耐久力和温度减少量装置的试验方法外文文献翻译、中英文翻译
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发展中的新一代轮轴流动性：第一部分—测量轮轴齿轮润滑油耐久力和温度减少量装置的试验方法外文文献翻译、中英文翻译,发展,中的,新一代,轮轴,流动性,第一,部分,测量,齿轮,润滑油,耐久,温度,减少,装置,试验,方法,外文,文献,翻译,中英文
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XXXXXXXXX设计（XXX）翻译资料中文题目：发展中的新一代轮轴流动性：第一部分测量轮轴齿轮润滑油耐久力和温度减少量装置的试验方法英文题目：Developing Next Generation Axle Fluids :Part 1Text Methodology to Measure Durability and Temperature Reduction Properties of Axle Gear Oils学生姓名： 学 号： 班 级： 专 业： 指导教师： 发展中的新一代轮轴流动性：第一部分测量轮轴齿轮润滑油耐久力和温度减少量装置的试验方法摘要：近几年来，轻型卡车和运动实用车辆（SUVs）美国是异常地流行，但是这种转变给大型客车的齿轮润滑油提出了新的要求。在美国北部，汽车制造商所面对的关键挑战是在保证汽车一定耐久力的前提下，满足政府的燃料节约要求。齿轮润滑油必须能够提供长时间的耐久力，并且能够对温度进行操控，以便在恶劣的条件下，既能保持燃料效率又能增加设备的使用寿命。这篇论文描述了在整个范围内轻型承载轮轴的发展。它模拟了多种不同的驾驶条件，以便根据齿轮润滑油公式来测量温度的减少。这里介绍的工作略述了一种试验方法论，既在考虑由于磨损和试验条件不同的情况下，对几种齿轮润滑油公式进行了对比。试验结果是从多种不同的轮轴结构和装载条件下获得的。这种试验方法论表明：当对比试验结果时，如果遇到恶劣的条件，考虑轮轴变化的重要性。介绍：过去的几年里，在北美的社会生活中，再次兴起了提高轻型卡车和使用运动车（SUVs）燃油节约效率的要求。汽车制造商们也把提高燃油效率作为他们改革汽车的一个战略性目标。基于这一点，厂家们生产齿轮润滑油时的目的就是希望能够帮助应用其润滑油的设备改善燃油节约的状况。这项任务看似简单，实际并不是这样。除了节约燃油外，人们还需要齿轮润滑油能够在不同的压力条件下保护轮轴构件。这些不同条件包括高速磨伤、低速重载磨损、腐蚀和氧化。在轻型卡车和赛车中，齿轮润滑油必须能够提供常时间的耐久力，并能够在极端的条件下实现对温度的控制，例如拖车的牵引支架或超高速的行驶。但是为了延长周期而使温度升高，相反也会影响装置材料并且减少了薄膜厚度的流动性。这些都会导致设备过早失效。以我们的观点，温度的控制是耐久力的一个重要的指标。然而，现在节约燃料已经成为了新一代润滑油的一个新的驱动力。任何燃料节约方面的改善都不可以牺牲轮轴耐久力或性能，这一点已经越来越明显。提高燃料节约率可以通过U.S. EPA 55/45操纵循环来测量。汽车制造商通过这种试验来保证汽车的节能性能。这种试验同样也可以用于检验齿轮润滑油的节能效果。许多制造商都感觉到在合适的可控的条件下，稳定工作温度在是不同的条件下润滑油耐久力性能的一个重要指标。在估计工作温度的条件下，是没有试验方法或方法论的。当在实验室里应用时，可以通过反复试验同规格的轮轴的强度来评估许多种润滑油，这是一个典型的试验。在恶劣的条件下，每次用在轮轴上的给定参考润滑油的稳定工作温度都会降低。随着轮轴运转次数的增加，给定润滑油的稳定工作温度都会有所降低。这在评估候选润滑油时又造成了新的问题。伴随着这个变化的目标，怎样才能精确地评估润滑油的指标呢？这篇论文描述了一种实验室的测试方法。这种方法考虑了各种试验间相互影响对轮轴造成的改变，并且给出了精确的比较试验结构的润滑油公式。另外，论文也对这种方法的一些共同的缺陷和操作指导方针做出了解释。这篇论文被分为四部分。第一部分，描述了这种试验台的发展及应用的程序；第二部分，详细讨论了试验方法论；第三部分，通过运用这种试验方法得出结论；最后，第四部分总结了论文的发现并且给出了一些结论。第一部分轮轴实验台结构研究人员设计了能够测量整体范围的轮轴功率计实验台，并且建立了用于模拟多种操纵的条件。图1是这种实验台的示意图。这个图表阐明了轮轴的索具设备和它的主要组成部分。实验台示意图见图2。图1 轮轴实验台示意图 图2 实验台照片实验台配置动力是通过以汽油为燃料的7.4升V8引擎提供给轮轴的。引擎能够承受重载，有4种速度的自动变速传动。这就可以通过获得的数据来进行速度的自动转换并且来控制（DAC）系统。用于评估润滑油性能的轮轴是严格地被固定在实验台上的。驱动轮轴的能量是被两个空气旋涡流功率计吸收的。在轮轴的末端和功率计之间放置了一个加速器，这样可以获得较高的输出速度，来代替输入功率计的较低速度。目前，习惯上用的实验台是柔性的，并且配有一个能够迅速变化的扭矩测量仪。或者说从小型客车轮轴到大型高速公路运货车轮轴，轮轴工具夹可以适应很大范围的轮轴型号。扭矩测量仪连在驱动轴上的单线整体式扭矩测量仪能够测量由小齿轮输入轮轴的扭矩。利用两个扭矩测量仪可以测量由轮轴输出到功率计的扭矩。在轮轴轴端和速度加速器之间也放置了一个输出扭矩测量仪。另外，常用的扭矩测量仪是提高了精确度的直流操纵模型。这样可以提高并保持一个高的精度等级，还可重复精度性。为了保证测量的精准程度，这些扭矩测量仪是需要周期性校准的。轮轴冷却及温度监测系统我们在轮轴的后面放置了一个风扇，并向轮轴吹进空气流，用以模拟在实际旷地工作台上从轮轴测得数据相匹配。另外，在轮轴的周围还放置两个喷雾水管，他们可起到两个作用。第一，当轮轴停止运转时，喷雾水管可以控制润滑油的温度。第二，它们对轮轴润滑油的高温可起到保护作用。根据润滑油的评估结果，这个试验程序具有承受较高轮轴润滑油的温度的能力。为了保护轮轴，在每个实验台边都标有最高温度的极限。另一个主要问题是对周围空气以及轮轴润滑油温度的测量。因此，我们必须注意热电偶的放置位置。轮轴润滑油温度是通过直接放置在轮轴环状齿轮边的一个热电偶来测量的。热电偶是通过临时改造的轮轴盖子放在那里。在由风扇产生的空气流中，周围温度是通过放置在那里的热电偶测得的，为了保证精确的温度测量结果，两个热电偶都需要进行周期性的校准。获得数据及控制系统ADAPT/MRTP数字信号系统用于操控实验台并且通过试验获得结果。除了周围环境和润滑油的温度，这套系统还可以监控并记录其它试验结果，如温度（发动机油、传动机油、齿轮箱、燃料及冷却剂温度等），扭矩（一个输入及两个输出扭矩），速度（发动机、小齿轮、轮轴杆）以及轮轴效率（输出扭矩与输入扭矩比）。这些数据都是需要研究人员周期性记录的。这个系统是通过5个控制回路来控制实验台的。用两个控制回路来维持小齿轮所需要的速度。通过调整功率计的电流来达到每个小齿轮所需转速。通过调整发动机来维持加在小齿轮上的负载。第四个控制回路用来控制轮轴在停止运转时的轮轴润滑油温度。在评估润滑油时，还可以用这个回路防止高温损坏轮轴。最后，第五个控制回路可以保证自动传输装置通过实验台上每一个合适的齿轮。自动传动装置要能恰当能够地控制的小齿轮，这一点是非常重要的。在此试验的某些阶段，运行处于重载状态。在给定的试验阶段中，如果传动没有控制在合适的小齿轮上，就会产生早期失效。第二部分试验方法一般说来，对于润滑油耐久力的评估是通过对确定其稳定工作温度和轮轴效率来评定的。这些评定是在一些不连续的速度扭矩条件下进行的。参考机油-相关机油是这个试验方法论的关键。在这个试验程序的编制以及对润滑油的评估中，应用了两种相关机油。其参数如下： 优质润滑油：人造SAE75W-140 劣质润滑油：人造SAE75W-90这种优良的参考机油在多种恶劣的使用条件下已经显示出了显著的工作性能。在恶劣环境条件的试验中，这种机油在降低温度方面的功能十分突出，它用于轮轴的暂停运转条下，并且在一给定的轮轴上进行周期性地试验，以次来追踪在稳定工作温度方面发生的任何改变。低质润滑油同样可以用于野外试验，但与优质润滑油相比，它不能提供相同水平的耐久力，在恶劣条件下减少温度升高的能力也不如优质润滑油。然而，试验表明，这种润滑油在节约燃料方面的贡献却更突出。这种参考机油用于核实区分在野外提供不同性能的机油的试验程序。轮轴断裂轮轴在用于评估润滑油之前要进行一个断裂试验。这个试验在一系列被控制的负载和速度条件下进行的。通过断裂试验程序（这里叙用温度不得超过250F，即121C），可以确定轮轴润滑油温度。优质参考机油可以用于断裂试验。试验阶段在断裂试验之后，可以通过确定稳定工作温度及在五种不同速度和负载的组合下来评估备选润滑油的性能。表1五种试验条件 试验阶段 通常条件 相关条件 1 高转矩/低转速 重载-加速 2 中等转矩/高转速高速-平整路面 3 中等转矩/中等偏高转速 重载-平整路面 4中等偏高转矩/中等转速 重载-中级 5 高转矩/中等偏下转速 重载-高级每一负载试验阶段都要进行润滑油的稳定工作温度点为止。这一般哟啊进行1.5到2.5个小时。一旦达到了稳定工作温度，下一阶段试验便开始了。直到评估了所有试验阶段，这个循环才能停止。在每个试验阶段结束时，记录周围空气温度，稳定的润滑油温度以及稳定的轮轴效率。周围空气温度调整装置-周围空气温度的变化会影响轮轴润滑油的稳定工作温度，这一点已经可以观察到。由于这种试验方法是在实验室里进行的，这里周围空气温度可能会发生变化，所以必须考虑周围空气温度的变化。将轮轴润滑油的温度作适当调整以适应周围空气的变化是按下述等式进行的： 这里，-由于周围空气而修正的润滑油温度（F）-测得的润滑油温度（F）-测得周围空气的温度（F）在应用下述方法论之前，要根据周围空气温度的不同来调整轮轴润滑油的温度。相关温度变化随着在轮轴上的试验数目的增加，对于给定的任意单一油源的负载条件下，稳定工作温度会有所降低。这一实际情况给备选润滑油有提出了新的难题。过去为了解决这个问题，可以周期性地测试参考机油，并将备选机油的试验结果与参考机油的实验结果进行了对比。然而，如果每次试验后，和上次参考结果相比都有所降低，那么实际上，备选机油比参考机油更好。图3表明了在轮轴上测试优质机油时，在五种不同阶段条件下稳定工作温度的变化。对于这个试验程序，这种趋势会发生在所有五种试验阶段。图3试验轮轴的优质参考既有在五种不同试验阶段条件下的稳定工作温度参考目标温度为了能够在参考机油与备选集中有之间做出较正确的比较，用于比较的参考机油的稳定工作温度需要按照轮轴运转次数进行调整。调整的参考机油温度或称为“参考目标温度”可以与备选机油稳定工作温度进行比较。基于参考试验数据，考虑随着在轮轴上的测试转速的增加而使参考稳定工作温度的减少量，可获得每一试验阶段的等式。对于每一根被测试的轮轴都需要做这样的工作。一旦生成恰当的公式，备选机油结果能够与参考机油性能进行精确的比较。图4是优质参考机油的稳定工作温度在五种不同试验条件阶段的曲线。图4 优质参考机油在第5种试验条件下的稳定工作温度曲线从图4中的等式可以看出，在每一试验阶段中，轮轴每次运转后，参考目标温度都可以计算出来。现在，备选试验结果就可以参考试验结果进行精确的比较了。另外，既然我们的比较与参考机油有关，可以通过这个方法中的公式与更多不同轮轴上的试验获得的结果进行精确的比较。轮轴效率变化随着稳定工作温度的变化，在试验轮轴上同样的作哟功能也会产生在轮轴功率的测量上。轮轴效率会随着在轮轴上进行试验次数的增加而逐渐增加的。图5试验结果表明了轮轴效率的变化以及参考目标效率等式。图5在第二阶段条件时试验轮轴的寿命条件下对优质参考机油稳定轮轴效率的评估在试验的每一阶段，稳定轮轴效率与稳定工作温度都是成反比的。这一点在我们的试验程序中已经得到了证明。效率越高，工作温度就越低。因此，这篇论文中阐述的方法论是可以应用与两者的。重复试验的估计我们可以从在每个轮轴上的参考试验结果来估计试验的重复性。这是通过比较给定试验阶段的轮轴的每个参考试验中实际稳定工作温度与计算参考目标温度的不同来完成的。例如，在图4中，第五阶段条件计算出的试验重复性是5.9F。而根据在实验阶段运行中，对轮轴和润滑油的测试中，我们估计这个重复性是在0.5到8.0F范围内。任何给定轮轴的试验重复性都受到试验备选机油质量很大影响。若在试验中采用质量差的机油，将对试验轮轴的结果产生影响。这里额外介绍了实验台之中的可变性。因此，为了达到最小的变化程度，在运行中采用高质量的机油是十分重要的。第三部分试验结果这篇论文所呈现的试验结果主要论证了这种试验程序的有效性。这个试验程序是作为恶劣的工作条件下，检验润滑油减少温度升高的能力。这部分主要分成三个小部分来阐述。野外试验相关性试验阶段的数据是要比野外试验数据早些得到。为了模拟车辆实际的运行环境我们设计了这个实验台。我们将实验台上获得的结果与野外工作获得结果进行比较，然后对实验台上轮轴气流系统进行修改直到输出结果与野外试验结果一致。对在野外试验车辆和实验台上的已知机油进行比较。在这个试验里，我们将优质机油和劣质机油都进行了这方面的比较测试。比较方法差异从上述等式看出，每次试验运行结果的参考目标温度都可以计算出来。图6表明了参考目标方法在机油评估方面的改进，以及两种等式方法之间的比较。两种方法比较了在单次试验阶段中优质机油的备选试验结果。方法1是将备选的机油的稳定润滑温度与上一个参考机油稳定温度结果进行比较。方法2是将备选机油稳定润滑温度与经备选轮轴运转次数所得的目标温度进行比较。图6两种数据等式方法的比较第四部分概要关于这篇论文中描述的试验方法论的应用实现了在恶劣条件下，对齿轮润滑油更多精确的评估。当遇到恶劣的工作状况时，应用这些技术需要首先介绍能够提供一定耐久力性能的高质量润滑油。试验结果表明在评估润滑油质量时这种试验方法的可行性。就像由U.S. EPA 55/45所测得的驾驶循环在恶劣的工作环境也提供一定的耐久力一样，我们希望这种试验程序在发展燃料推进润滑方面也可以发挥作用。400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: SAE TECHNICALPAPER SERIES2002-01-1691Developing Next Generation Axle Fluids:Part I Test Methodology to MeasureDurability and Temperature ReductionProperties of Axle Gear OilsEdward S. Akucewich, James N. Vinci,Farrukh S. Qureshi and Robert W. CainThe Lubrizol CorporationInternational Spring Fuels & LubricantsMeeting & ExhibitionReno, NevadaMay 6-9, 2002The appearance of this ISSN code at the bottom of this page indicates SAEs consent that copies of thepaper may be made for personal or internal use of specific clients. This consent is given on the condition,however, that the copier pay a per article copy fee through the Copyright Clearance Center, Inc. OperationsCenter, 222 Rosewood Drive, Danvers, MA 01923 for copying beyond that permitted by Sections 107 or108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying forgeneral distribution, for advertising or promotional purposes, for creating new collective works, or forresale.Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department.To request permission to reprint a technical paper or permission to use copyrighted SAE publications inother works, contact the SAE Publications Group.No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior writtenpermission of the publisher.ISSN 0148-7191Copyright 2002 Society of Automotive Engineers, Inc.Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solelyresponsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published inSAE Transactions. For permission to publish this paper in full or in part, contact the SAE Publications Group.Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE.Printed in USAAll SAE papers, standards, and selectedbooks are abstracted and indexed in theGlobal Mobility DatabaseABSTRACTLight trucks and sport utility vehicles (SUVs) havebecome extremely popular in the United States in recentyears, but this shift to larger passenger vehicles hasplaced new demands upon the gear lubricant. The keychallenge facing vehicle manufacturers in North Americais meeting government-mandated fuel economyrequirements while maintaining durability. Gear oils mustprovide long-term durability and operating temperaturecontrol in order to increase equipment life under severeconditions while maintaining fuel efficiency.This paper describes the development of a full-scale lightduty axle test that simulates a variety of different drivingconditions that can be used to measure temperaturereduction properties of gear oil formulations. The workpresented here outlines a test methodology that allowsgear oil formulations to be compared with each other whileaccounting for axle changes due to wear and conditioningduring testing. Results are shown from a variety ofdifferent axle configurations and loading conditions. Thistest method shows the importance of accounting forchanges in the axle when comparing test resultswhenever severe conditions are experienced.INTRODUCTIONWithin the last few years, there has been a reneweddesire to make fuel economy improvements in NorthAmericas light trucks and sport utility vehicles ( SUVs).Vehicle manufacturers have set aggressive fuel efficiencyimprovement objectives for these vehicles. Because ofthis, gear lubricants have been targeted to contribute fueleconomy improvements over the current products used inthese applications.This is not as easy as it may seem. In addition toacceptable fuel economy, gear lubricants are required toprotect axle components under a variety of stressedconditions. These include high speed scuffing, low speed,high torque wear, corrosion and oxidation. In light truckand racing applications, gear oils must provide long-termdurability and operating temperature control underextreme conditions, such as trailer towing or extendedhigh speed applications. Higher operating temperaturesfor prolonged periods can adversely affect metallurgicalproperties and reduce fluid film thickness, both of whichcan lead to premature equipment failures. In our view,operating temperature is an important indicator ofdurability.While fuel economy is now the driving force in nextgeneration lubricant development, it is clearly recognizedthat any improvements in fuel economy must not be at theexpense of axle durability or performance.Fuel economy improvements can be measured via theU.S. EPA 55/45 driving cycles(1). Automotivemanufacturers use this test to certify a vehicles fueleconomy. This test can also be used to show fueleconomy improvements in gear oil lubricants.Many manufacturers feel that stabilized operatingtemperature under the proper controlled conditions is animportant indicator of the durability performance of alubricant under severe conditions. In the case of operatingtemperature assessment, there exists no standard testmethod or methodology. Typically, when applied in alaboratory test stand a single axle is broken-in and thenused repeatedly to evaluate many lubricants. Undersevere conditions, the stabilized operating temperaturesfor a given reference oil decreases each time it is run in anaxle. As the number of test runs on an axle increases thestabilized operating temperature of the reference oil islower. This poses a problem when evaluating candidatelubricants. With a changing target, how can a lubricantbe accurately evaluated?This paper describes a laboratory test method thataccounts for test-to-test changes in the axle and gives thelubricant formulator an accurate way of comparing testresults. In addition, common pitfalls of this method andoperating guidelines will be described.2002-01-1691 Developing Next Generation Axle Fluids: Part I Test Methodology to Measure Durability and Temperature Reduction Properties of Axle Gear Oils Edward S. Akucewich, James N. Vinci, Farrukh S. Qureshi and Robert W. Cain The Lubrizol Corporation Copyright 2002 Society of Automotive Engineers, Inc.2The remainder of this paper is divided into four parts.First, the test stand used to develop and utilize the testprocedure is described. Second, the test methodology isdiscussed in detail. The third section focuses onpresenting test results that demonstrate the usefulness ofthe test methodology. Finally, the last sectionsummarizes the papers findings and offers someconclusions.PART 1 - AXLE TEST STAND CONFIGURATIONThis full-scale axle dynamometer test stand was designedand set up to simulate a variety of operating conditions. Aschematic of the test stand is shown in Figure 1. Thisfigure illustrates the axle rig and its major components.Figure 2 shows a picture of the test stand.Figure 1:Schematic of Axle Test StandInputtorqueOutput TorqueMeter (2)Output TorqueMeter (1)Box shroud + fan(optional)ENGINE: V8 GASOLINEDynamometerDynamometerSpeedIncreaserSpeedIncreaser3Figure 2:Photograph of Test StandSTAND CONFIGURATION - Power is supplied to the axleby a gasoline fueled 7.4 liter V8 engine through a heavyduty 4-speed automatic transmission that can beautomatically shifted by the data acquisition and control(DAC) system. The axle used for lubricant evaluation isrigidly mounted to the stand. The power driven throughthe axle is absorbed by two air gap eddy currentdynamometers. A speed increaser is placed between theaxle wheel end and the dynamometer to boost outputspeed to the dynamometer for low speed applications.The stand used is flexible and with a quick change oftorque meters and/or axle fixtures is able toaccommodate a wide range of axle sizes, from smallpassenger vehicle axles to large on highway truck axles.TORQUE METERS - A single in-line torque meter integralto the drive shaft measures the input pinion torque to theaxle. Two in-line torque meters measure the outputtorque from the axle to the dynamometers. One outputtorque meter has been placed between each axle wheelend and speed increaser.In addition, the torque meters used are the enhancedaccuracy, DC operated models. This was done toincrease and maintain a high degree of accuracy andrepeatability. These torque meters are periodically deadweight calibrated to insure accurate torquemeasurements.AXLE COOLING AND TEMPERATURE MONITORING -Behind the axle a fan is positioned to provide airflowacross the axle. This was done to simulate the actualairflow cooling experienced in field tests. The fan speed,size and position were selected to produce temperaturesin the axle which match field test data for the axle beingtested.In addition, two water spray nozzles are positioned aroundthe axle. These spray nozzles are used for two purposes.First, they are used to control the lubricant temperatureduring axle break-in. Second, they provide protectionagainst high axle lubricant temperatures. Depending uponthe lubricant under evaluation, this test procedure has thepotential of experiencing very high axle lubricant4temperatures. To protect the axle, high temperature limitshave been put in place for each test stage.Another major concern is the measurement of the ambientair and axle lubricant temperatures. Thus, care was takento properly position the thermocouples. The axle lubricanttemperature is measured by a thermocouple positioneddirectly next to the axle ring gear. The thermocouple isheld in place by a specially modified axle cover. Theambient air temperature is measured by placing athermocouple in the air stream produced by the fan. Boththermocouples are periodically calibrated to insureaccurate temperature measurements.DATA ACQUISITION AND CONTROL SYSTEM - A DSPRedline ADAPT / MRTP system is used to control theoperation of the stand and to acquire data throughout thetest. In addition to the ambient and lubricanttemperatures, this system monitors and recordsadditional temperatures (engine oil, transmission oil,dyno, gear box, fuel, and coolant), torques (input and twooutputs), speeds (engine, pinion, axle shafts, and dynos)and axle efficiency (ratio of output torque to input torque)throughout the test. Data is logged periodically.This system controls the operation of the stand with fivecontrol loops. Two control loops are used to maintain the desiredpinion speed. This is done by modulating eachdynamometer current to achieve a desired pinion rpm. The load on the pinion is maintained by adjusting theengine throttle. A fourth control loop is used to control the axlelubricant temperature during axle break in and toprevent high temperatures from damaging the axleduring lubricant evaluations. Finally, a fifth control loop is used to insure that theautomatic transmission is running each test stage inthe appropriate gear.It is important that the automatic transmission isoperating in the proper gear. Some of the test stagesduring this test run at relatively high loads. Prematurefailure will occur if the transmission does not operate inthe appropriate gear for a given test stage.PART 2 - TEST METHODIn general, the evaluation of the lubricants durability wasassessed by determining its stabilized operatingtemperature and axle efficiency at a number of discretespeed / torque conditions. The test procedure used isdescribed below.REFERENCE OILS - Reference oils are critical to thistest methodology. For the development of this testprocedure and evaluation of lubricants, two reference oilswere used. The fluids used as reference oils are asfollows:Good Reference: Synthetic SAE 75W-140Poor Reference: Synthetic SAE 75W-90The good reference has been shown to provideoutstanding performance in a wide variety of severeservice applications. This fluid provided excellenttemperature reduction in a controlled severe duty fieldtest. This reference oil is used to break-in the axle and isperiodically tested on a given axle to track any changesthat might occur in stabilized operating temperatures.The poor reference was also field tested and did notprovide the same level of durability or temperaturereduction in severe conditions as the good reference.Testing has shown however that this lubricant providesmeasurable fuel economy benefits. This reference oil isused to verify that the test procedure can distinguishbetween oils that provide different levels of performance inthe field.AXLE BREAK-IN - Before an axle can be used forlubricant evaluation, a break-in procedure is run. Thisprocedure consists of a series of controlled load andspeed conditions. The axle lubricant temperature iscontrolled throughout the break-in procedure where it isnot allowed to exceed 250F (121C). The good referenceoil is used for the break-in procedure.Running an adequate break-in is critical in preparing theaxle for accurate lubricant evaluations. Once broken in anaxle can run multiple candidate lubricant evaluations.TEST STAGES - Following the break-in procedure,candidate lubricants are evaluated by determining thestabilized operating temperature and efficiency at fivecombinations of speed and loads (stages) to approximatedifferent severe operating conditions. Table 1 outlines thetest conditions used.5Table 1Durability and Operating Temperature Test ConditionsSTAGEGENERAL CONDITIONCORRELATIONIHigh torque / low speedHeavy Load - Start-UpIIModerate torque / high speedHigh Speed - Flat SurfaceIIIModerate torque / moderate-high speedHeavy Load - Flat SurfaceIVModerate-high torque / moderate speedHeavy Load - Moderate GradeVHigh Torque / low-moderate speedHeavy Load - Steep GradeEach of the load stages is run until a stabilized lubricanttemperature is achieved. This typically takes 1.5 to 2.5hours. Once a stabilized temperature is reached, thenext test stage is started. This cycle is repeated until alltest stages have been evaluated. At the completion ofeach test stage, the ambient air temperature, stabilizedlubricant temperature and stabilized axle efficiency isrecorded(2).AMBIENT AIR TEMPERATURE ADJUSTMENTS - It hasbeen observed that changes in ambient air temperatureaffect the stabilized operating temperature of the axlelubricant. Since this test method was run in a laboratorywhere the ambient air temperature may vary, changes inambient air temperatures must be accounted for.Adjusting the axle lubricant temperature to account forambient air temperature changes is done by normalizingthe axle lubricant temperature relative to an ambient airtemperature of 80F with the following equation:Tcorrected =Taxle + (80F Tambient)Where,Tcorrected =lubricant temperature (F) correctedfor the ambient air temperature.Taxle=measured lubricant temperature(F).Tambient=measured ambient air temperature(F).Before applying any of the methodology described below,the axle lubricant temperature is adjusted to account forambient air temperature differences.REFERENCE TEMPERATURE CHANGES - As thenumber of tests run on an axle increases, the stabilizedoperating temperature for a given load condition of anysingle oil is lower. This fact poses a problem whenevaluating a candidate lubricant.To solve this problem in the past, reference oil is testedperiodically and the candidate result is compared to thelast reference test result. However, if the reference testtemperature gets lower after each test run, comparing thecandidate to the last reference result will make thecandidate seem better than it actually is relative to thereference.Figure 3 shows the change in stabilized operatingtemperatures for stage V conditions on a test axle whenthe good reference oil is tested. The stabilized operatingtemperature goes down as the number of test runs on theaxle increases. For this test procedure, this trend occurson all 5 test stages.6Figure 3:Stabilized Operating Temperature For the Good Reference Oil Over the Life of a Test AxleUnder Stage V ConditionsREFERENCE TARGET TEMPERATURE - To make a faircomparison between a reference and a candidate, thereference oils stabilized operating temperature used forcomparison should be adjusted for the number of runsmade on the axle. This adjustment must be done foreach test stage and lubricant evaluated on an axle. Theadjusted reference oil temperature or “reference targettemperature” can then be compared to the candidate oilsstabilized operating temperature for the load stage inquestion.Based on the reference test data, an equation for eachtest stage can be generated taking into account thereduction in the reference stabilized operating temperatureas the number of test runs increases on an axle. Thismust be done for each axle tested. Once generated,candidate results can be accurately compared toreference oil performance. Figure 4 shows a curve fittedto the stabilized operating temperatures of the goodreference oil for Stage V test conditions.Stabilized Axle TemperatureGood Reference Oil Stage V Conditions180200220240260280Increased Axle RunsCorrected Temperature (Deg F)7Figure 4:Curve Fitted To Stabilized Operating Temperature Results for Good Reference Oil on a TestAxle Under Stage V ConditionsFrom the equation developed in Figure 4, a referencetarget temperature can be calculated for each test run onthe axle for each test stage. Candidate test results cannow be accurately compared to reference test results.In addition, this method allows the formulator to moreaccurately compare results that were tested on differentaxles since your comparison is relative to the referenceoil.AXLE EFFICIENCY CHANGES - Just as with thestabilized temperature, a similar effect occurs with theaxle efficiency measurements on test axles. The axleefficiency gradually increases as the number of tests onan axle increases. Figure 5 shows the changes in theaxle efficiency and the reference target efficiency equationdeveloped from the test results.Stabilized Axle TemperatureGood Reference OilStage V Conditionsy = 0.0172x2 - 1.4508x + 237.02R2 = 0.9302200210220230240250260Increased Axle RunsCorrected Temperature (Deg F)8Figure 5:Stabilized Axle Efficiency Values For the Good Reference Oil Over Life of a Test Axle UnderStage II ConditionsIt has been our experience with this test procedure thatthe stabilized axle efficiency for any test stage is inverselyproportional to the stabilized operating temperature. Thehigher the efficiency, the lower the operating temperature.Thus our primary focus in the paper is on the operatingtemperatures and not the axle efficiencies. The testmethodology described in this paper can be applied toboth.ASSESSMENT OF TEST REPEATABILITY - Testrepeatability can be estimated from the reference testresults on each axle. This is done by comparing thedifferences between the actual stabilized operatingtemperature and the calculated reference targettemperature for each reference test in an axle for a giventest stage. For example, the test repeatability wascalculated to be 5.9F for Stage V conditions shown inFigure 4. Our experience has been that repeatabilityestimates range from 0.5 to 8.0 F depending upon thetest stage run, axle used and lubricants tested.(3, 4)The test repeatability on any given axle is greatly affectedby the quality of the candidate oils tested. Running apoor quality oil affects the results of the tests that run onthe axle after it finishes. This introduces additionalvariability in the test stand. Thus it is important to rungood quality oils to minimize variability.PART 3 - TEST RESULTSTest results presented in this paper are focused ondemonstrating the validity of this test procedure for use asa tool to evaluate the temperature reducing capabilities oflubricants under severe operating conditions. This sectionis divided into three parts.FIELD TEST CORRELATION - The test stages describedearlier were developed from field tests data. They aredesigned to represent actual conditions experienced byvehicles in use. Results produced by the test stand werecompared to results from the field. Modifications weremade to the stand axle airflow system until the standstest results matched the field test results. Thecomparisons were made between known oils run in fieldtest vehicles and the test stand. For this test, wecompared the laboratory test results for both the poor andgood reference oils with the same oils run in the field test.Stabilized Axle EfficiencyGood Reference OilStage II Conditionsy = 0.001x2 - 0.0136x + 97.77R2 = 0.94769797.197.297.397.497.597.697.797.897.998Increased Axle RunsAxle Efficiency (Percent)9COMPARISON METHOD DIFFERENCES - From theequations developed above, a reference target temperaturecan be calculated for each test run. Figure 6 shows theimprovement in oil assessments that can be made byusing the reference target method. Figure 6 shows acomparison between two evaluation methods.Both methods compare candidate test results with thegood reference oil test results for a single test stage.Test runs 1,2,5,8,11 and 14 were good reference runs.Method 1 is comparing the candidate oil stabilizedlubricant temperature to the last reference oilstabilized temperature result.Method 2 is comparing a candidate oil stabilizedlubricant temperature to the calculated referencetarget temperature for the candidates axle runnumber.Figure 6:Comparison of Two Methods of Data EvaluationDurability Test ResultsCandidate ComparisonsStage IV Data-50510152025303540455055123456789101112131415Test Run Number on AxleTemperature Difference Between Candidate and Reference (Deg F)Method 1: Delta - Last ReferenceMethod 2: Delta - Target ReferenceDifference Between Methods10Positive deltas indicate that the test in question ran at ahigher operating temperature than the reference.Likewise, a negative delta indicates that the test ran at acooler temperature than the reference. Note that somevalues for method 1 are zero. In all cases
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