I've been round the back

This is the working end of the windy handle lever jobby that had the cnc jobbie on. The bar pulls in and out, acting on the lever thing which in turn disappears into the hydraulics.
Am i right in thinking that this lever is the fine tuning for the tonnage, or for the stroke? I've been happily bending away, just by careful setting of the knurled force setting knob thing on the left hand side.
The second picture needs rotating 90 degree to the left to get it in the correct orientation, but it crops the picture down. The lever with the spring on it is the bit that sticks out of the machine that had the cnc thing on.