A platform is positioned above {TAIL ~ the conveyor} and is capable of alternatingly moving in either one of a first direction, substantially similar to the direction of {HEAD ~ motion} of the conveyor, and a second direction, substantially opposite to the direction of motion of the conveyor 
A platform is positioned above { TAIL ~ the conveyor } and is capable of alternatingly moving in either one of a first direction , substantially similar to the direction of { HEAD ~ motion } of the conveyor , and a second direction , substantially opposite to the direction of motion of the conveyor
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH