摘要:

Techniques to condition monitor check valves in reciprocating pumps that are used to load pressure tanks (300 bar) in a high pressure system are described. Currently the condition of the pumps is monitored by the operator using indicators such as the extra time taken to load a pressure tank and changes in the audible sound radiated from the pumps.

ISSN:1040-2004    

DOI:10.1080/10402009108982040

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The wear reducing actions of bronze, graphitic powder and discontinuous glass fiber fillers within a PTFE matrix have been demonstrated in oscillatory contact with stainless steel, at two different amplitudes, over a range of speeds. The secondary effects on the friction of the PTFE have also been investigated. The effects of oscillation amplitude on frictional surface morphology have been observed for these composites. The friction and wear of the unfilled PTFE matrix were both found to increase as speed increased, with wear going through a transition from a low-to high-rate regime. The speed at which this transition occurs increases with decreasing oscillatory amplitude.Presented at the 45th Annual Meeting In Denver, Colorado May 7–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982041

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Sliding friction phenomena have long been the subject of study and modeling. The physical portrayal of the sliding contact upon which such models are based is often a function of the modeler's background, and may range from the atomic scale to the scale of more macroscopic surface roughness. Sometimes, quasi-static arguments are inappropriately applied to sliding situations. The current paper examines the nature of frictional variations during sliding contact. High recording-rate instrumentation was used to analyze detailed, point-to-point variations in friction force for self-mated, pin-on-disk experiments with alumina and aluminum specimens. Data indicate that friction mechanisms, even on a fine scale, must be modeled considering the whole tribosystem, not just the interfacial materials properties alone. The contact conditions stimulate the displacements in the tribocomponents, which in turn result in sensible mechanical output. It is physically unrealistic to develop sliding solid friction models which predict only a single friction value, rather a range of values typical of the variation experienced by the dynamic tribosystem should be developed. A systems approach rather than a discrete asperity approach may ultimately prove to be most productive for modeling tribosystems of engineering interest.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference In Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982042

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This study demonstrates the closed-form solutions for simulation of a braking temperature generation during inertia dynamometer tests of railroad wheels and brake discs subject to single and multiple uniform and non-uniform braking actions. These methods, compared to other techniques, have a higher level of flexibility and allow for a rapid (a matter of seconds) and accurate computer solution of related braking problems.

ISSN:1040-2004    

DOI:10.1080/10402009108982043

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

An analysis is presented to find the effect of the elasticity of the lubricant in polymer containing multigrade oils on the performance of a dynamically loaded rotor, supported by short journal bearings. This paper solves for the loci of the center of a journal, subjected to unsteady loading, using Newtonian and viscoelastic lubricants. The viscoelastic fluid is described by a relatively new rheological equation which has been shown to be successful in predicting the experimental trends of various unsteady high shear rate flows. The analysis is a perturbation solution for low Deborah numbers where the stress relaxation process is a first-order effect. The results show an improvement in the performance of viscoelastic lubricants over Newtonian lubricants. Under an unsteady load, the journal center orbits show reduced eccentricity and travel of the journal due to the elasticity of the fluid. It implies that lubricants with a longer relaxation time can be developed where the viscosity and viscous losses can be reduced without adverse effect on the wear, resulting in a significant saving of energy.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982044

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The results of an experimental study are presented in which the raceway surfaces of tapered roller bearings were intentionally pre-dented with single, large indentations. Contact stress analysis results and the observed changes in the surface near the indentations during run-in are described. Depending on indentation size, extremely high initial contact stresses are predicted at the raised shoulders surrounding the indentations. After running-in for 7.58 million revolutions at a moderate load level, these shoulder stresses drop to approximately 4.1 GPa (600,000 psi) or less. Microcracking and micropitting are observed around the indentations, corresponding to the areas of stress elevation. The microcracking develops during the first 100,000 revolutions of the run-in period, and is often observed to follow the direction of the abrasive finishing marks on the raceway surface.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference In Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982045

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Textile spinning rings, being the easily worn part in the ring textile spinning frame, are consumed in a great quantity annually. It is found that in cotton spinning, cotton wax coats the frictional surface of spinning rings and lubricates it. During normal operation, uniform oxidative wear occurs on the surface of the rings, the wear rate being in general low; only an undue early failure is caused by localized scoring taking place in unsteady motion. In this paper, a method of lengthening the service life of the rings is discussed.Presented at the 44th Annual Meeting in Atlanta, Georgia May 1–4, 1989

ISSN:1040-2004    

DOI:10.1080/10402009108982046

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Experimental measurements of pressure distributions and force coefficients obtained from a squeeze film damper lest rig executing a circular centered orbit are presented. The test rig has been designed to study the effect of fluid inertia on the pressure field and dynamic force response on a damper configuration with a relatively large clearance. Past measurements of the squeeze film damper force characteristics have been carried out at squeeze film Reynolds numbers not exceeding a value equal to 10. In the present paper, following contemporary applications, operations at Reynolds numbers up to fifty are tested for CCO's with an orbit radius = 0.8 (Re ≤ 10 at ε = 0.5). The results obtained from a fully open ended damper are presented in detail. The effects of fluid inertia, cavitation and the open end geometry on the pressure distributions and force coefficients are discussed.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982047

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

In Part I, a squeeze film damper (SFD) test rig and measurement procedures were explained, arid the experimental results obtained from an open ended damper were presented. In this paper, the experimental results measured from a partially sealed SFD test rig executing a circular centered orbit are presented and discussed. A serrated piston ring is installed at the damper exit. This device involves a new sealing concept which produces high damping values while allowing for oil flow to cool the damper. In the partially sealed damper, large cavitation regions are observed in the pressure fields at orbit radii ε = 0.5 and ε = 0.8. The cavitated pressure distributions and the corresponding force coefficients are compared with a cavitated bearing solution. The experimental results show the significance of fluid inertia and vapor cavitation in the operation of squeeze film dampers. Squeeze film Reynolds numbers tested reach up to Re = 50, spanning the range of contemporary applications.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990

ISSN:1040-2004    

DOI:10.1080/10402009108982048

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The objective of this work is to quantify the effect of shear rate on the viscosity of multigrade lubricants. The study is based on the assumption that multigrade lubricants are two phase systems with the phases responding more-or-less independently to external mechanical actions. The assumption generates two questions: 1) Are there rules of behavior respected by all members of a given family of blends (same additive in different concentrations and the same class of base oils with different viscosities)? and 2) To what extent do the nature of the additive and the base oil affect these rules?

ISSN:1040-2004    

DOI:10.1080/10402009108982049

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor