Making heavy duty chain - GIF

[Frank S]

I can't quite figure out the use of that forward arm...seems it's only to align the link vertically for the welding clamps??

PJs there are 2 arms one in front and one in back yes for true centering each alternative link must be rotated opposite of the previous. Other wise the chain would become a twisted ball of a mess for both the welded and yet to be welded links the rapid moving arm to the left shears off the excess due to the forced induction welding.
TM 51 that machine is probably uses as much electricity in one day as I use all summer