Singer 34K3/Singer 45K65 parts

[Zol]

Both machines have an additional short bar connected from above to foot bar. I am not really shure about function

My Singer 34(pre34 model) does not have it

 

At 34, it seems to do nothing, until food is lifted (or not really much)

The 45 lifts foot on it's own after each stitch.
and so the whole device does

Other models known having this are for example 16KSV11, 16KSV23, 34K5 (not all, due model change or remove), 34KSV5, 45K48, 45K53....