Some light hints that may point you in the right direction:
Hint 1
The assembly is a part of a larger machine.
Hint 2
Several assemblies are meant to move side by side in unison.
Hint 3
The square-ish shaped piece is plastic that will wear down and be replaced.
Oh MF i swear i saw something like this in my subaru service manual to keep the timing sprocket in place while you have the belt off.
Lol. It's not car related. This is for a larger stationary machine.