| 摘要 |
Support props for use in mines comprise a timber element 11, base frame and headboard. The timber element 11 includes, expansion grooves 12 proximate at least one end and a core 14 between the grooves 12. The periphery of the at least one end is discontinuous. The base frame engages a lowermost portion of the timber element 11 and restricts movement of the timber element 11 along the base frame. The headboard engages an uppermost portion of the timber element 11 and restricts movement of the timber element 11 along the headboard. <IMAGE> |
