| 摘要 |
A mine roof truss including opposed angularly disposed roof bolts, a horizontal truss member extending between the roof bolts, and couplings connecting the roof bolts to the truss member. Each coupling comprises a housing having walls forming a cavity into which the head of the roof bolt and an end of the truss member are inserted and secured. The end of the truss member is provided with a T-shaped head which is inserted through a slot in the housing wall leading to the cavity, following which the truss member is rotated relative to the housing to lock the truss member to the coupling. The roof bolt head and truss member are pivotally connected with the coupling to permit adjustments thereof when installed on an uneven roof surface. |
