摘要:

AbstractSix diamond coatings were produced by microwave plasma‐assisted chemical vapour deposition (MW PACVD) on polished SiC substrates. Process gas pressure and process gas composition were varied systematically, resulting in different coating morphologies, roughnesses and grain sizes.Friction and wear were investigated for unlubricated vibrating contact conditions in air at room temperature. Tribological tests on diamond coatings were performed in a ball‐on‐disc configuration, with steel balls (100Cr6) and alumina balls acting as counterbodies. For comparison of the tribological performance of the diamond coatings, standard tests were performed with a stroke of 200 μn, a load of 10 N, and a frequency of 20 Hz. The effect of relative humidity (RH) was investigated by testing in dry (3% RH), in normal (50% RH), and in moist air (100% RH), respectively To investigate running‐in effects and wear propagation, the test duration (104, 105, and 1.2·106sliding cycles) was varied.For steel/diamond pairings, high wear at the steel ball and high friction were measured, influenced by roughness and grain size of the diamond coating and by relative humidity. For Al2O3against diamond, a pronounced running‐in of friction and wear was found. High friction and high wear at the beginning of each test are followed by a stationary phase with extremely low friction coefficients (⩽ 0.05) and with wear rates below the limit of resolution. This running‐in depends on grain size and roughness of the coating, on relative humidity, as well as on the operational parameters. Surface analysis using SEM, EDX, LRS and AFM was conducted, to investigate tribologically induced

ISSN:1354-4063    

DOI:10.1002/tt.3020040102

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractField samples of automatic transmission fluid (ATF) from vehicles fitted with controlled‐slip torque converter clutches have been analysed to determine the cause of the onset of vehicle shudder. A laboratory anti‐shudder test has been developed using the SAE No. 2 machine. This test includes several degradation mechanisms: thermal degradation in engaging clutches, oxidative degradation in the presence of catalytic metals, and degradation produced by a continuously sliding clutch. At least in the case of one specific fluid, the mode of failure produced in the laboratory test was very similar to the mode of failure in the vehicle. Fluids with improved anti‐shudder durability have been evaluated by this test method and fail by different mechanisms. Test matrices have been conducted to separate the contribution of fluid and hardware to the loss of shudder control in these sy

ISSN:1354-4063    

DOI:10.1002/tt.3020040103

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractA method is presented for determining the efficiency of gear units in test rigs with a mechanically closed energy flow, based on measuring the losses in the rig, that is, the torsion torque at the driving motor and the stabilised thermic level. The energy losses between the two gear units would be separated according to the direction of power flow within the stressed framework of the rig.Experimental results are given for gear units including three types of gears, i.e.: involute gears with hobbed toothing, involute gears with ground toothing, and Wildhaber/Novikov (W/N) non‐involute circular arc gears with two meshing lines, achieved by hobbin

ISSN:1354-4063    

DOI:10.1002/tt.3020040104

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractDiagnosis of diesel engines is not new and various methods have been proposed in the past for fault diagnosis. The problems relating to marine diesel engines, especially medium‐ and high‐speed engines, are due mainly to their large size, which does not allow the use of trial and error methods, and their high operating speed. The most difficult problem occurs when the engine is not able to produce its maximum power, while there is no obvious fault or error. In the present work a method is described which attempts to offer a solution to such problems. The method is a thermodynamic one based on a simulation model and the processing of measured engine data. Presented is an application of the method to a medium‐speed marine diesel engine, which suffered from low power output accompanied by high exhaust gas temperatures. The results from application of the method show that the problem is not a direct one, but is caused by many factors that result in improper operation. With this method, the current engine condition can be discovered, and suggestions made for proper tuning or repair. After conducting such an analysis, a vessel was able to achieve its maximum cruising speed, showing that the proposed method is a promisin

ISSN:1354-4063    

DOI:10.1002/tt.3020040105

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

摘要:

AbstractIn agreement with isothermal EHD theory, increases in speed and lubricant viscosity determine the increase in film thickness. Beyond certain limits, both speed and viscosity lead to a decrease in film thickness, as a result of thermal effects and starvation. To estimate starvation limits and film thickness in high‐speed, mist‐lubricated ball bearings, a new analytical methodology has been developed. This methodology is based both on the oil flow rate in ball‐race contacts and Hamrock and Dowson's starvation theory. This new methodology has been used to estimate minimum film thickness in a 7206C angular contact ball bearing, axially‐loaded, and rotated between 0 and 35,000 r/min−1. Good correlation between computed and experimental values of the minimum film thickness have been

ISSN:1354-4063    

DOI:10.1002/tt.3020040106

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020040107

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020040108

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020040101

出版商:John Wiley&Sons, Ltd    

年代:1997

数据来源: WILEY