You’ve seen it before; a sweep comes to the sideline and the ball carrier and several other players go crashing out of bounds while the chain gang drops their equipment and runs for their lives.Â With the advent of instant replay, we’ve seen the chains set for a new series, but replay over-rules the call and the chains have to go back to their old position.Â How does the chain gang and the head linesman reset the chains after they are moved?
The chain gang uses what is called a clip.Â On the clip is a dial that has the numbers five through 50 in increments of five.Â On the dial is a clip that attaches to the chain links.Â The chains are, of course, 10-yards long so at least one yard stripe will always intersect the chain.Â The chain gang takes the clip, and attaches the clip at the back of the stripe.Â For instance, if it is first and 10 from the 21-yard line going out, the chain gang attaches the clip on the 25-yard line at the back of the stripe (so it is more accurate) and dials the clip so it shows the number 25.Â There is one man on the chain gang dedicated to maintaining the clip.Â He notes the clip’s yard line every new series.Â When the referee calls for a measurement, the head linesman jogs the chains out to the spot of the measurement and, in this instance, places the clip on the back side of the 25-yard line.Â Once the measurement is over, the head linesman resets the chain if it’s not a first down, or the chain gang sets the chains on the new spot, and the “clip man” places a second clip at the proper spot and notes the new yard line.Â
That’s all well and good, but what happens when there’s a first down, but instant replay over-rules the call and the chains have to be reset to the old line to gain?Â In the NFL and NCAA, two leagues that use instant replay, the chain gang uses two, sometimes three clips.Â When there is a new series, the clip man clips a second clip to the new yard line, and momentarily leaves the “old” clip attached to the chain.Â If instant replay or some other situation calls the chains back to the old position, the clip man and head linesman consults the clip man’s notes as to what yard line the old clip was on, returns the old clip to its proper stripe, and the chains stretch out.Â Once a play is run and the previous play cannot be reviewed, the clip man removes the old clip.Â
This clip is vital to fix the line to gain at a constant point.Â The chain gang goes off of the head linesman on where to set the chain stakes on a new series.Â While it may not be accurate to the millimeter, every NFL field is very accurately marked and the head linesman and chain gang are pretty darn close in setting the stakes accurately every first down.Â
While quite a lengthy explanation, the chain clips are quite a simple and accurate system in keep the line to gain a constant point on every series.Â