on the side which is pressed against the front of the machine

[kikkiriki]

on the side which is pressed against the front of the machine - что это означает в след. контексте?

To increase the life of packings special anti-extrusion and support rings can be used; these rings are made of high-performance plastic. Normally two rings are used on each plunger: one is placed before
the packing on the side which is pressed against the front of the machine, and one is placed immediately after the packing, before the bronze packing washer; in some configurations washer is not present.
These rings are also considered wearing parts and should be replaced regularly to maintain perfect coupling with plunger, preferably when changing the packings or when they are showing signs of wear in the inner diameter.

[vottaktak]

со стороны, которая упирается в переднюю часть (торец) машины