Although the major elements of the process reside in the grate and kiln, a cooler is added to the system.
An annular cooler is a turntable that holds the hot pellets. The ambient air is blown through the hot pellets. The turntable is made of wedge shaped pans. The pellets fall out of the kiln directly onto the pans. The pellets travel all around the turntable until the pan is tipped and the pellets fall underneath. The pan is then righted to accept more material. The cooler pans are supported by rollers. Each of these rollers require lubrication. It is for this reason that advance lubrication systems are developed.