I'm translating a Russian text about a drug product manufacturing process. The text mentions briefly the vial stoppering machine, in which rubber stoppers are first fed into the hopper and then directed towards vials, and a пуансон drives the stopper into the vial. Multitran provides multiple options for how to translate this "пуансон". It's basically some shaft-like member.
I googled and found a description of some stoppering machine in Russian, and it has a diagram, with "пуансон" under number 60:
The text there says that the axle (59) rotates, making the cam (58) rotate and push this.. plunger\piston\punch member (?) towards the vial and drive the rubber stopper into the vial.
I'm unsure which word to use for this part.