| 摘要 |
<p>1,124,489. Advancing mine roof supports. BERGWERKSVERBAND G.m.b.H. Dec. 7, 1965 [Dec. 30, 1964], No.51898/65. Heading F1P. In a hydraulic mine roof support system comprising a plurality of advanceable roof support units arranged in groups, each support unit has means for feeling the working face and is arranged to generate a control signal when there is sufficient room ahead of the support to allow the support to advance, the signal only becoming effective to initiate the advancing sequence of the support unit when the unit has also received a time signal arranged to be fed in succession to all the support units of a group at predetermined intervals of time. Each support unit may comprise a sliding roof bar 1 guided between two fixed roof bars 2 and urged mechanically, pneumatically or hydraulically against the working face. When the sliding bar of a support is fully extended, electrical contacts 5a, 5b close to produce the control signal and when the support also receives the time signal from a transmitter an electrical circuit including the contacts 5a, 5b is completed to cause the support to advance. At the end of advance further contacts 6a, 6b are made to cause the support to re-set. Alternatively the cessation of the time signal after a predetermined duration may cause the support unit to re-set. The control signals may also be sent by a feeler switch on each support which is responsive to the distance from a conveyer situated between the supports and the working face. If any support fails to advance the full distance a feeler switch may cause (a) operation of an acoustic and/or warning system, (b) the stopping of the conveyer or of a cutting machine or (c) the further lowering of the roof bar of the support.</p> |
