Hydraulic coal face lining system uses an initial pressure level at the ram, followed by a second and higher pressure level after a time delay, to increase the tunnel lining rate

摘要

The hydraulic tunnel lining system in underground mining, e.g. coal mining, uses an initial operating hydraulic pressure on the hydraulic ram. When the first pressure level is achieved, a second and higher hydraulic pressure is applied after a time delay. The first pressure is 300 bar, and the second pressure is 400 bar. The two pressure levels are provided from separate sources, with a control block at the tool to change from one stage to the other.