What part of the drag chain barrel should contact the sprocket tooth?
It is sometimes surprising to me how many times I am asked, “What direction should drag chain travel?” First, let’s discuss the barrel. The concept behind a drag chain is simple, to push material along a conveyor. The barrel, commonly referred to as a “D” barrel (due to it’s shape), is designed with a flat side (for pushing) and a round side (the drive side) for making contact with the drag chain sprocket. The round side makes contact with the sprocket as the sprocket teeth are designed to accept the roundness of the barrel, thereby being the drive side. If the flat side were to come in contact with the sprocket tooth, there would be no forgiveness between the drag chain sprocket tooth and the barrel, resulting in barrel failure. The weight of the material being conveyed along with force of the sprocket would destroy a barrel.
Which end of the drag chain should go first; Big end or Little end?
There has been much debate about this over the years. Little end or big end first? For years, standard chain travel was the little end of the drag chain going first. Years later, someone experimented with the big end of the drag chain going first and it was called “reverse barrel.”
So which way is best? Quick story. A customer of mine was running a multi strand drag chain conveyor consisting of (4) strands of WDH 480 and it was running with the little in first (standard direction) and had no attachments, or wings (3″ wings mounted to both sides of the chain, usually spaced out every few pitches, or links.). The problem that kept coming up was the motor running the conveyor kept tripping the breaker. After digging into this problem, and I happened to be onsite during a chain change out, I watched in disbelief as it literally took a crane to extract the chain from the conveyor, and it was not easy. What happened was the chain wedged itself into the conveyor due to the little end running first and, as the big in followed behind, it compressed the material against the side of the conveyor. In addition, the reason why the motor was tripping the breaker had also been reviled.
The solution? Adding wings to the chain would have solved the problem as it would allow uniformity between the attachments and the side of the conveyor. Since that was not an option, we installed Reverse Barrel WDH 480 drag chain. The problem was immediately solved and the conveyor has not had another issue in almost 10 years.
I look at it this way, with the big end, or wide end, going first, it allows for uniform spacing of material between the chain and the edges of the conveyor…especially for plain chain, or chain without wings. Usually, and in this case, there was no additional cost for purchasing Reverse Barrel Drag Chain. The initial installation will require a way to connect the two “little” ends of the chain, but once that is done, installing the next chain will be done in the usual manner. In addition, according to some engineers, running Reverse Barrel Drag Chain allows the chain to release from the sprocket quicker thereby, in theory, can increase the life of the chain and the sprocket.