4 Prevent wasting of raw material and time. 5. There will be no material leakage. B. Structure of the screen changer 1. Structure: The screen changer together by front board, seal ring, filter board, side is jointed board, screw nut, back seal ring. hydraulic tank. oil pipe and back board hydraulic station. The back board is jointed with barrel, the front board jointed with die head. The high-pressure oil will be pumped from hydraulic pressure reducer and station and will go changing valve, so that the changer can be moved through di to both left and right side for filter changing.