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Post by bahhnhof35 on Mar 8, 2016 19:42:30 GMT -5
Hello everyone! I need some idea about shield advancing problem. The production method is LTTC. When shield advance to face, then its front postion turns to T/G. And back of the shield turns to M/G. Seam has 7° slope towards M/G. What can be reason of this problem? And any solution offers? ![]()  |
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Post by dazbt on Mar 9, 2016 3:09:15 GMT -5
Hello everyone! I need some idea about shield advancing problem. The production method is LTTC. When shield advance to face, then its front postion turns to T/G. And back of the shield turns to M/G. Seam has 7° slope towards M/G. What can be reason of this problem? And any solution offers? ![]() Hy bahhnhof35, where is this installation and who is the shield manufacturer? I ask because I am very surprised that this problem of 'downhill creep' hadn't been discussed even before the face was installed. If it is as occurring as I believe your description shows, then this problem exists on all inclined longwalls that I've ever worked on, the shield manufacturers have surely experienced this and should be able to provide a sequential chock operation plan that should be able to counteract this creep. Does the AFC to shield ram connection have variable positions i.e can the ram be connected to a position off centre to the pan? I have to admit though that I have never worked on LTTC and can't therefore speak about the effect of the rear conveyer on the situation. |
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Post by John on Mar 9, 2016 16:51:46 GMT -5
Never heard of this problem before, but then I worked on fairly level seams the last few years I worked underground. I did a little research and would hazard a guess you have a Caterpillar face installation, with Chinese made Shields??
What does the Cat rep say about the problem??
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Post by dazbt on Mar 10, 2016 1:52:58 GMT -5
If it is a Cat installation then I would be even more surprised to hear that they are not involved in correcting this creep problem. Basically the Main Gate (rise side) end should be in front of the Tail Gate (dip side) end, the advance being created by graded cuts or if needs be, by taking graded fly cuts at the Min Gate end, once this is achieved the creep should be reduced but must be maintained then by pushing over in careful sequence, it may be necessary to move the shield push over ram position on the AFC pan to give an inclined shove, i.e. set the ram clevice nearer to the Main Gate in order to gain an 'uphill' biased shove. Do these shields have side rams?
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Post by John on Mar 10, 2016 6:41:33 GMT -5
If it is a Cat installation then I would be even more surprised to hear that they are not involved in correcting this creep problem. Basically the Main Gate (rise side) end should be in front of the Tail Gate (dip side) end, the advance being created by graded cuts or if needs be, by taking graded fly cuts at the Min Gate end, once this is achieved the creep should be reduced but must be maintained then by pushing over in careful sequence, it may be necessary to move the shield push over ram position on the AFC pan to give an inclined shove, i.e. set the ram clevice nearer to the Main Gate in order to gain an 'uphill' biased shove. Do these shields have side rams? |
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Post by dazbt on Mar 10, 2016 7:09:03 GMT -5
If it is a Cat installation then I would be even more surprised to hear that they are not involved in correcting this creep problem. Basically the Main Gate (rise side) end should be in front of the Tail Gate (dip side) end, the advance being created by graded cuts or if needs be, by taking graded fly cuts at the Min Gate end, once this is achieved the creep should be reduced but must be maintained then by pushing over in careful sequence, it may be necessary to move the shield push over ram position on the AFC pan to give an inclined shove, i.e. set the ram clevice nearer to the Main Gate in order to gain an 'uphill' biased shove. Do these shields have side rams? I believe that most roof supports are made with side-shields, in negotiating creep the hydraulic type can be used to advantage but the operators have to be careful in using (or not using) them. There can be quite a few factors that cock-up or complicate the ease in which creep can be controlled. On steeper seams when first starting to drive one end forward of the other the face length is obviously affected and might need AFC extensions. I worked on an extremely difficult thin seam in Spain which two changes of grade in its length, 1:4 and 1:2, before I got there the creep was uncontrollable, their answer had been to wait until the first chock "dropped" into the main gate then disconnect it, take out a pan and transport them round to the tail gate to add on, poor guy in the tail gate corner was nearly worked to death setting props and casting towards an ever disappearing AFC. |
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Post by John on Mar 10, 2016 8:33:24 GMT -5
I recall pan creep on the old 16/125 faces, but it was pretty common and I'd say anyone of our age saw it Daz. End of week remove a couple of pans at the M/G and add a couple at the T/G, in fact something tells me we had a few "short" pans for that very purpose. But as we know it was caused by bad pushing over routines. Again, I'm pretty sure experienced face crews learned how to counter the effect by leaving the face back after the shearer ploughed back, then start pushing the face over from main to tail gate. Never saw pan creep on bi di shearer faces.
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Post by dazbt on Mar 10, 2016 8:53:22 GMT -5
I recall pan creep on the old 16/125 faces, but it was pretty common and I'd say anyone of our age saw it Daz. End of week remove a couple of pans at the M/G and add a couple at the T/G, in fact something tells me we had a few "short" pans for that very purpose. But as we know it was caused by bad pushing over routines. Again, I'm pretty sure experienced face crews learned how to counter the effect by leaving the face back after the shearer ploughed back, then start pushing the face over from main to tail gate. Never saw pan creep on bi di shearer faces.
Yep, always had a "half-pan" up yer cuff. |
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Post by dazbt on Mar 10, 2016 9:16:50 GMT -5
I recall pan creep on the old 16/125 faces, but it was pretty common and I'd say anyone of our age saw it Daz. End of week remove a couple of pans at the M/G and add a couple at the T/G, in fact something tells me we had a few "short" pans for that very purpose. But as we know it was caused by bad pushing over routines. Again, I'm pretty sure experienced face crews learned how to counter the effect by leaving the face back after the shearer ploughed back, then start pushing the face over from main to tail gate. Never saw pan creep on bi di shearer faces.
Amongst the thousands of lessons learnt longhand in days of yore, how to grade a pan line through swillies, over humps using wedge lids and grading chains, steering a fixed drum shearer using speed control and or "scientific" pick removal etc .................. all gone, smothered by technology !! |
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Post by John on Mar 10, 2016 17:18:35 GMT -5
When we started Daz, they were still learning, how long had the Anderton Power Loader been around? 8 or 9 years at the most in 1964, and there were still a lot of pits with no mechanised faces back then.
I think the last hand got face at Clifton had been finished around 1963ish, I'd have to look through my notes. The first power loader face at Clifton was 41's, still cutting until 1966, I'd have to look at the abandonment plans to see when it started, but hazard a guess at 1959. Then 10's, 51's, 43's, 52's and the last one started was 53's.
10's was lost to converging, 12's due to water and convergence, 41's reached the boundary, 52's and 53's finished early due to men being transferred to other pits, and finally 51's finished mid 68, then salvage crews salvaged all equipment, shafts filled and capped.
I believe by 1963, 50% of UK coal was mined by machines.
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Post by dazbt on Mar 28, 2016 12:19:00 GMT -5
bahhnhof35, any news updates, have you managed to stabilise the creep yet?
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