In order to improve power efficiency in hydrostatic bearings a research project was found to minimize the leakage in this type of bearing. One concept for this solution is to use greases as lubricant. The non-Newtonian behaviour of greases which is determined by a characteristic yield stress builds the point of interest. The scope of this paper was to examine if self-sealing is reachable in a thrust bearing and can be predicted by simulation. Therefore an experimental setup and a numerical calculation model were developed. The results confirm the hypothesis and define possible operation conditions for this approach in the field of hydrostatic bearings.
Keywords: non-Newtonian fluid, tribology, Bingham Fluid, lubrication, hydrostatic bearing, power efficiency

This study demonstrates the utility of estimating the volume fraction of air in hydraulic oil by measuring the effective bulk modulus of the oil. In this paper, we propose a method for measuring and calculating the effective bulk modulus and volume fraction of air in oil and report experiments that show the validity of the method by comparing with the results measured by another method. Our results clarify that the volume fraction of air in oil can be determined by measuring the effective bulk modulus of the oil.

The shaft counterface of a radial shaft seals is usually plunge ground. With the aim to reduce costs and production
times, many companies try to use new and alternative manufacturing processes for that task. For example, belt
grinding and superfinishing methods are frequently considered and used. Result of these often-unreflecting
changes of the manufacturing methods, is often leakage and increased wear of the sealing components as well as
other related problems. Because, there is only little information about the functional behaviour of this types of
surface finishes in terms of sealing applications, an experimental investigation has been carried out. This paper
presents the results of these experiments.

The performance requirements of multiple sealing systems for reciprocating movements are continuously
increasing with friction, wear and service time being key performance criteria. The new concept, presented in
this paper, is about adjusting lubrication conditions of all single sealing elements within a sealing system so the
load on each element can be reduced and the performance in terms of friction-wear-lifetime can be optimized.
This paper describes the dilemma in terms of optimizing the performance of the primary and secondary seal and
brings up a new seal concept, where the risk of leakage of lubricant is balanced to ensuring performance of the
primary seal and the extended life of the secondary seal.