City Research Online

Abstract

The literature survey on reciprocating seals revealed a considerable lack of data relating to the film thickness of the lubricant film under such a seal and the work described is an attempt to remedy this. Significant progress towards this end has been achieved both experimentally and theoretically.

Two experimental approaches were used, the first using optical interferometry to study the film formation between a rubber pad specimen and a reciprocating glass plate, the second a reciprocating seal test rig on which the film thickness and pressure in the lubricant film could be measured under conditions typical of those experienced in a hydraulic jack.

The theoretical approach again took two forms. The first using the ‘inverse’ solution of Reynold's equation, did not provide a unique solution to the problem, but allowed a rapid estimate of the effect on the film profile of small changes in the pressure profile. By suitably modifying a measured film profile, film profiles typical of those measured could be obtained. In the second approach a stable solution was obtained for the elasticity and Reynold's equations. Variables such as rubber hardness, sealed pressure and speed were studied in this approach.

The results, which are presented in Imperial Units, show that in general the outstroke film thickness is thicker than the instroke and hence seals will inherently leak and the measured values of friction are considerably higher than expected from the measured film thickness profiles.

The elastohydrodynamic behaviour of reciprocating rubber seals is shown to be complex and dependent on many factors, many of which relate to the seal material itself, which cannot be directly controlled.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Department of Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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