Hydraulic pit prop unit - is made of light metal covered with woven steel or copper alloy mesh with outer plastics cover

摘要

The pit prop unit may be made of woven mesh from CR, N1, Cu or T1 alloy. The lower layer may be plastics whilst the outer layer(4) may be high grade steel. The mesh is woven wire with a thickness of between 0.5 to 1 mm. Al is inner core may be used, the outer cover may alternatively have a hard anodic layer. Adhesion of outer and inner cover may be accomplished by glueing or ultra sonic heat sealing.