from a vertical path to a horizontal path while maintaining the horizontal orientation of the top surface 90 of the flight to assure that the chains 20 22 are maintained in a taut condition each of the chains passes through a chain tightening device 270 272 which is a series of opposed and laterally adjustable but vertically spaced arcuate guides best seen in fig1 which can be moved laterally into the path of the chains to increase the path length of the chains and therefore remove any slack from the chains it has been found to be advantageous to construct the flights 18 out of a light weight yet sturdy plastic material and many of the components such as the guides 250 252 and 260 262 as well as the chain tightening devices 270 272 can also be made of a light weight yet sturdy plastic material to reduce the manufacturing cost as well as the weight of the conveyor system further although two separate motors 24 63 are shown for running the conveyor chanis and infeed powered conveyor 34 respectively a single motor could be utilized with appropriate gear ratios to provide the necessary speeds for the conveyor chains 20 22 and the infeed belt 34 speeds.