turn point will be the double cut setting when in Bidirectional mode or the turn point at the other endgate in the unidirectional mode. The picture below represents the tailgate of 175 shield face. Several things can be seen in this picture: ● Parameter “TG Turn Point from TG” is set to 5 which positions the turn point at shield 171. The shearer has actually gone one shield farther then necessary to shield 172 so the shield system is ready for the shearer to turn around and go back the other direction. ● Parameter “Auto HG Safe Zone” is set to 6 so the closest shield that has advanced is #165, leaving the Primepoint at shield 166. ● Parameter “TG Cleanup Area” is set to 8; when the shearer turns around and leaves the cleanup area (i.e., position becomes 167) the system will begin trying to advance the tailgate shields. If parameter “Auto TG Safe Zone” is set to 6 also, then shields 173 through 161 will be in the shearer zone when the position is at shield 167; this means that initially only 175 and 174 will be triggered to advance.
Unidirectional Cutting Cycle SRB parameter “Cycle” must be set to “UNIDI” to use SRB in a unidirectional cutting cycle.
Parameter “Cycle”
There are two modes of unidirectional cutting: Half-Web Cutting, also known as Partial-Web Cutting; and Full-Web Cutting. In half-web cutting, a partial-web cut of coal, both top and bottom, is taken on both passes. In full-web cutting, a full depth cut is taken of the top coal on one pass and a full depth cut is taken of the bottom coal on the same pass or on the pass in the other direction
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