Improvement of reliability of dozers through taking into account hydrodynamic phenomena in fluid power systems

Abstract

Improvement of reliability of mining machines and equipment is a complex challenge. It is required to take into account many specific operating conditions, as well as physical processes and phenomena running in such machines. Such phenomena include dynamic and hydrodynamic events. One of the factors to affect reliability of fluid power drives of mining machines is the hydrodynamic phenomena and processes in these systems. This article describes theoretically one of the hydrodynamic events, namely, a surge of pressure (overpressure) which appears in fluid power systems of mining machines in case of stop of the fluid flow while the pump keeps working and the emergency valve acts tardily, which is governed by settlement of resinous substances and power fluid decomposition products on the surface of parts of hydraulic equipment. The experimental studies into the time dependences of vibrational accelerations of the force main walls enable correlating these vibrations with pressure surges because of retar ded actuation of the emergency valve in the fluid power system of a dozer. The total level of vibrations of the force main walls in the dozers is measured by the parameter of the emergency valve series PIK during blade lifting, which agrees with the time dependences of the vibrational accelerations of the force main walls. The technical consequences of the pressure surges are described. The authors propose a diagnostic sign to judge about the behavior of emergency valves. The experimental nondestructive testing used a commercial vibration analyzer with a piezoelectric sensor.