On some longwall installations the radial shearer drum can offer a single or combination cutting system which means it can be used as a coal laced drum or a rock laced drum without having to remove toolholders/blocks and without the need to have two sets of shearer drums.

This is a unique feature of the radial shearer drum and is achievable because the toolholders/blocks are located in the vanes and positioned flush with the top of the vanes as can be seen in the following picture.

The lacing can be changed by removing certain picks from the shearer drum. This layout drawing shows an example of a radial shearer drum layout with a 3 start 3 pick per line lacing.
If you need to change the lacing because cutting conditions change you can remove specific picks/bits from the toolholders/blocks highlighted on this layout drawing to convert the drum to a 3 start 2 pick per line lacing.
If you need to change the lacing further you can remove more picks/bits as shown in this layout drawing to convert the drums to a 3 start 1 pick per line lacing.

After removing the pick/bit a blanking insert is positioned inside each toolholder/block to protect it from wear whilst operating without a pick/bit in it. It takes just a few minutes to insert each blanking unit and can be done without removing the shearer drums from the ranging arms.

Although This feature is available on all multi pick per line radial drum designs, not all mines can utilise this option but on certain applications, the combination shearer drum allows the longwall operator to optimise cutting performance and minimise pick/bit usage, even when they encounter changing geological conditions.