horizontally along the rail and vertically by luffing (raising and lowering) its boom. Luffing of the boom minimizes dust by reducing the distance that material such as coal needs to fall to the top of the stockpile. The boom is luffed upwards as the height of the stockpile increases. Some stackers can rotate the boom. This allows a single stacker to form two stockpiles, one on either side of the conveyor. Stackers are used to stack in different patterns, such as cone stacking and chevron stacking. Stacking in a single cone tends to cause size segregation, with coarser material moving out towards the base. In raw cone ply stacking, additional cones are added next to the first cone. In chevron stacking, the stacker travels along the length of the stockpile adding layer upon layer of material.

Circular / Radial Stacker
The circular system comprises a luffing / slewing stacker rotating around a central column, covering the entire area of the circular stockpile. The Material will be fed to the center of the stockpile by means of an overhead belt conveyor. The slewing stacker boom performs a continuous, combine slewing and luffing motion over a preset arc of the circle during stacking to form an endless bed.

Stacker has three basic movements:
•Luffing
•Travelling
•Slewing