| 摘要 |
<p>1,239,833. Advancing mine roof support systems. BERGWERKSVERBAND G.m.b.H. 22 May, 1968 [31 May, 1967], No. 24447/68. Heading E1P. [Also in Division F2] In an advancing mine roof support assembly for a longwall comprising a series of frames each connected to the conveyor by a double-acting jack and arranged in groups for automatic control to maintain alignment relative to adjacent groups, each group of frames has a series of auxiliary frames whose incremental advance is determined relative to a guide frame. The control system includes a group switching arrangement which in predetermined sequence passes control pulses from the auxiliary frames to a comporator control to which the guide frame is connected in parallel, see Fig. I (not shown). The comporator control for each group of frames comprises a cam mechanism 40 actuated by two jack units 43, 45 operating in opposite directions. An input 21 to the control leads from the group switching arrangement whilst pulses from the guide frame are fed thereto via a line 33. An input pulse fed to line 21 passes through a valve 48 to a line 21a thereby effecting a one step advance of the associated auxiliary frame, the valve then being closed by the unit 43. The second step advance of the said frame is effected by a further control pulse fed through the line 21 and a valve 49 until this valve in turn is closed by further rotation of the cam mechanism by the unit 43. Pulses fed from the guide frame to line 33 rotate the cam mechanism in the opposite direction to open the valves 51, 52 in sequence and close the valves 48, 49; the sequential opening of the valves 51, 52 causing two step advance of the next auxiliary frame of the group via a line 32. The arrangement is such that the auxiliary frames can only beat the guide frame by a maximum of two steps. Logic components of electrical, pneumatic or hydraulic design may be interconnected in the control line of the system and to this end line 33 leads to a. computerised control for the whole system.</p> |
