摘要:

Lubricants influence energy efficiency mainly through reducing energy losses, which include churning losses and friction losses in hydrodynamic, elastohydrodynamic and boundary lubrication regimes. The total energy loss depends on lubricant viscosity and chemical composition. Different sources of lubricant-related power losses in industrial systems are described. The dependence of churning and friction losses on oil properties is analyzed.

ISSN:1040-2004    

DOI:10.1080/10402009908982281

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The vapor pressure of TCP was determined by measuring the loss rate under vacuum conditions at 50°C. The mass loss of a four-component aryl phosphate ester additive mixture was also measured. The loss-rate was modeled, and the component vapor pressures were determined by fitting the model to the experimental loss data. The values measured were significantly lower than those obtained through extrapolation of higher-temperature vapor pressure data.

ISSN:1040-2004    

DOI:10.1080/10402009908982282

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Cylindrical roller bearings are being developed which can operate over 300°C and greater than three million DN for innovative gas-generators. Under such severe conditions, it is necessary for retainers to be frictionless, lightweight and strong. After preliminary testing, SiC particle reinforced aluminum alloy composite appeared to have good friction and wear properties. It's specific gravity is about one-third of the present material in use, silver-coated SAE4340. In the course of the study, two different friction and wear tests were conducted to investigate the optimum volume fraction of SiC. The results indicated that the most efficient volume fraction was 20vol%. The tensile strength of Al-20vol%SiC was about 140MPa at 300°C. Based on the results of FEM analysis, 140MPa is considered sufficient to endure any stress concentration caused by tensile hoop stresses up to four million DN.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402009908982283

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Developing a system for dynamic stiffness and damping measurements for foil bearings is crucial for future advancements in the design and use of oil-free bearing technology. This paper addresses some of the preliminary issues involved in developing such a measurement system. Steady-state stiffness measurements are taken and used as a learning tool for the use and development of a fiber optic displacement probe system. The problems encountered with these probes and the problems expected in their use at high temperature are addressed. Some possible solutions for these issues are also discussed. From this effort it appears that it is feasible to experimentally characterize foil bearings at high speeds and temperatures.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402009908982284

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An experimental and numerical study of early fatigue failure due to dents in EHL contacts is presented. Tests are conducted on a two-disk machine with different operating conditions. Disks are made of AISI 52100 bearing steel. The surface of one disk is smooth. The other one is initially indented by M50 steel powder using the procedure presented in previous papers (1), (2). The oil is a synthetic one qualified under the MIL-L-23699 specification. The lubricant is cleaned during tests by using a β3μm= 200 cleaning filter. An optical microscope and a profilometer are used to describe the dent evolution, as the tests are stopped at regular intervals.

ISSN:1040-2004    

DOI:10.1080/10402009908982285

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Mechanical seals generally fail as the result of the collapse of the lubricating film between the faces. In the present research, a system that detects the collapse of the lubricating film in a gas seal has been developed. The system uses an active ultrasonic transmission technique to monitor the fluid film. Sensors are placed behind each stator of a double mechanical seal. A series of ultrasonic sinusoidal wave packets is generated by one transducer while the second transducer monitors the signal transmitted through the seal interface. A weak transmitted signal indicates a continuous fluid film, while a strong transmitted signal indicates contact between the seal faces. The transmitted signal is relatively independent of the seal characteristics and operating conditions, and can be easily distinguished from machinery noise since its frequency and amplitude can be controlled.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402009908982286

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Interactions between various engine oil additives including dispersant, detergent, antiwear/antioxidant, and viscosity index improvers have been investigated through changes in the31P-NMR and IR spectra. Significant changes in the31P-NMR and IR spectra of zinc dialkyldithiophosphate (ZDDP) have been observed by varying the blending order of additives. Dispersant-detergent (polyisobutylene succinimide-calcium overbased sulfonate) and viscosity index improver-detergent (dispersant olefin copolymer-calcium overbased sulphonate) interactions were found to be strong and irreversible in nature. Variable temperature31P-NMR spectra have provided enough evidence to suggest that the actual performance of an additive may not be decided by its bulk interactions with other additives at room temperature, and that tribochemical reactions occurring at higher temperature play a greater role.

ISSN:1040-2004    

DOI:10.1080/10402009908982287

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A study has been made of the lubricating properties of gasoline fuel. A conventional HFRR diesel fuel lubricity tester has been modified to measure gasoline wear. Using this test equipment, a number of features of gasoline lubricity have been investigated, including the comparative lubricating behavior of gasoline, the influence of detergent additives and oxygenates on wear and the wear behavior of a series of refinery streams employed in gasoline blending.

ISSN:1040-2004    

DOI:10.1080/10402009908982288

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An Association of American Railroads (AAR) class F (6 1/2 × 12) tapered-roller bearing assembly is modeled, using finite elements, to examine thermally-induced failures observed in the laboratory when the bearing is operating at relatively high speeds. It is hypothesized that this failure is caused by an unstable thermal expansion/internal bearing load feedback process. Sequentially-coupled, transient thermal and static structural models are used to obtain the thermal-mechanical transient time response as a function of speed, seal type, and lubricant starvation at the rib contact. The model assumes no external loads and zero initial preload (zero end-play). Therefore, the loads developed in the bearing are thermally-induced and self-equilibrated. Two train speeds, viz. 80 and 100 mph, are considered. Simulation results indicate that at axle rotational speeds equivalent to a train speed of 100 mph, a combination of grease starvation and heat flux from the contact seals cause high rib temperature and subsequent unstable load growth which will lead to failure. At rotational speeds equivalent to train speeds of 80 mph or for bearing assemblies that utilize special design seals, the rib temperature is relatively low and no operational instabilities were observed for the model used.Presented at the 54th Annual Meeting Las Vegas, Nevada May 23–27, 1999

ISSN:1040-2004    

DOI:10.1080/10402009908982289

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An experimental study of ceramic lubrication by tribopolymerization at high loads and high speeds, using a pin-on-disk (fixed ball-on-flat) machine with alumina-on-alumina, is presented. In order to extend the range of applied loads and sliding velocities beyond those used in previous studies, a three-factor, two-level designed experiment was carried out to determine the effects of monomer structure, load, and speed on wear. Five monomers of widely varying chemical structure were used at one percent concentration in a hydrocarbon carrier fluid, hexadecane. They consisted of (a) one condensation-type monomer, a partial glycol ester of a longchain dimer acid, and (b) four vinyl-type addition monomers. Two levels of load (40 and 160 N) and speed (0.25 and 1.0 m/s) - each varying by a factor of four were used; thus the range of frictional heat generation was 16 to 1.

ISSN:1040-2004    

DOI:10.1080/10402009908982290

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor