Minimizing Internal Leaks of a Powered Roof Support’s Hydraulic Prop Based on Double Block with Charging

Abstract

The hydraulic system of a powered roof support performs two functions. The first function is to control the powered roof support in the extraction wall. The second function is to protect against adverse overloads resulting from rock mass pressing directly on the powered roof support. This damaging phenomenon is prevented by the protection of the powered roof support, with a safety valve built into the hydraulic system or directly into the prop. However, the third function proposed by the authors based on the research results is to minimize leaks. These leaks usually develop in the props or in the hydraulic system. The authors propose implementing changes to the hydraulic system for this purpose. The change consists of replacing the existing support block with a double block with charging. Tests were carried out in real conditions, that is, a mining wall. Tests in the mining wall were carried out on the powered roof support’s leaking prop. As a result of charging, the actual load capacity of the prop increased by about 10–50% in relation to the load capacity before charging. The use of a double block with charging ensured that the pressure in the under-piston space of the prop was maintained at a minimum of 250 bar. The results allowed us to determine the usefulness of the proposed solution and eliminate its disadvantages—the designated direction of research and development on the powered roof support allowed us to expand its functionality by minimizing leaks.

Extraction and Application of Hydraulic Support Safety Valve Characteristic Parameters Based on Roof Pressure Data

“…Liu Z [15] analyzed safety valve nonactuation faults using roof pressure data. Szurgacz, D. [16,17] analyzed the pressure increase and internal pressure leaks in the hydraulic cylinder of a longwall powered roof support during use and determined the operating range of the safety valve through bench tests conducted on the prop and the safety valve under dynamic loads.…”

Mining Technologies Innovative Development II: The Overview

“…D. Szurgacz, B. Borska, R. Diederichs, A.J.S. Spearing, S. Zhironkin in their article consider new possibilities of internal leaks minimizing in hydraulic prop of a powered roof support [8], starting from its three functions: equipment control, overload protection-the result of rock pressure, minimization of leaks in props and in entire hydraulic system. To do this, the authors propose replacing the existing support block with a double block with charging, which allows increasing the load capacity of the prop by 10-50% by maintaining pressure in the under-piston space of at least 250 bar.…”