Characteristics of the stationary behaviour of water- and oil-based power-control hydraulics

F Majdič,M Kalin

doi:10.5755/j01.mech.20.3.5301

Abstract

In this paper we demonstrate with stationary pa-rameters the functionality of water hydraulics in compari-son to the usual oil hydraulics. The movements of the wa-ter hydraulics’ cylinder rod differed from the movements of the oil hydraulic cylinder by 2 to 6%. The pressures required to start the movement of the cylinder rod were up to 21% higher in the water hydraulics than in the oil hy-draulics. The working pressures required to move the cyl-inder rod with a constant velocity were 20 bar higher in the water hydraulics than in similar oil hydraulics. The great advantage of water hydraulics is the clear 45% to 65% lower pressure losses than in the oil hydraulic. The last stationary parameter that we evaluated was the time delay of the movement of the hydraulic cylinder rod. In water hydraulics this delay was 2 to 5 ms longer than in oil hydraulics. DOI: http://dx.doi.org/10.5755/j01.mech.20.3.5301

Highlights

When we talk about water hydraulics, we refer to the use of tap water – without any additives – for the hydraulic fluid, rather than the usual oils
The first curve in each graph is for the movement of the controlling spool in the proportional 4/3 directional control valve and the second is for the response of the movement of the hydraulic cylinder rod with a loading mass of 163 kg in the horizontal position at an inlet pressure of 160 bar and a flow 33 lpm
The loaded oil hydraulic cylinder rod has not returned during the symmetrical controlling signal to its start position

Summary

Introduction

When we talk about water hydraulics, we refer to the use of tap water – without any additives – for the hydraulic fluid, rather than the usual oils. One so-called “soft” solution is the use of biodegradable hydraulic oils [3,4,5,6,7,8], but here the problem is with the additives, which tend not to be totally degradable. For this reason, in the early 1990s, many countries [2, 9, 10] began with research into the possibilities of using tap water as a hydraulic fluid. The presented stationary measurement results for this new water valve are compared with accessible results from a commercially available oil hydraulic valve [14]

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Discussion

Conclusion