Printing press

Claim 1

A TWO-REVOLUTION FLAT-BED PRINTING PRESS COMPRISING, IN COMBINATION, AN IMPRESSION CYLINDER MOUNTED IN A STATIONARY SUPPORT AND MOVABLE ALTERNATELY INTO AND OUT OF IMPRESSION CONTACT WITH THE BED DURING A COMPLETE MACHINE CYCLE, SPRING MEANS FOR EFFECTING THE MOVEMENT OF THE CYLINDER OUT OF IMPRESSION CONTACT WITH THE BED, A ONE-WAY ACTING HYDRAULIC JACK UNIT FOR EFFECTING THE MOVEMENT OF THE CYLINDER INTO IMPRESSION CONTACT WITH THE BED AGAINST THE FORCE OF THE SPRING MEANS, SAID UNIT COMPRISING A STATIONARY CYLINDER HAVING A CONSTANTLY OPEN PORT FOR THE ADMISSION AND EXHAUST OF THE PRESSURE LIQUID AND A RAM SLIDABLY MOUNTED IN THE CYLINDER AND OPERATIVELY CONNECTED TO THE IMPRESSION CYLINDER, A HYDRAULIC PRESSURE LINE IN PERMANENT OPEN COMMUNICATION WITH SAID CYLINDER PORT, A LIQUID RESERVOIR, A CONTINUOUSLY OPERATING POWER DRIVEN PUMP FOR SUPPLYING LIQUID UNDER PRESSURE TO SAID PRESSURE LINE, A BY-PASS FROM THE PRESSURE LINE TO THE RESERVOIR, A VALVE LOCATED IN SAID BY-PASS AND MOVABLE ALTERNATELY TO OPEN AND CLOSED POSITION, AND AUTOMATIC MEANS FOR OPERATING SAID BY-PASS VALVE IN TIMED SEQUENCE WITH THE PRESS DURING EACH MACHINE CYCLE FOR, FIRST, CLOSING SAID VALVE TO ADMIT PRESSURE LIQUID TO THE JACK CYLINDER FOR MOVING THE IMPRESSION CYLINDER INTO IMPRESSION CONTACT WITH THE BED DURING ITS FIRST REVOLUTION FOR THE PRINTING OPERATION AND, THEN, OPENING SAID VALVE TO PERMIT THE PRESSURE LIQUID TO BE EXHAUSTED FROM THE JACK CYLINDER UNDER THE INFLUENCE OF THE AFORESAID SPRING MEANS FOR CAUSING THE IMPRESSION CYLINDER TO MOVE OUT OF IMPRESSION CONTACT WITH THE BED DURING ITS SECOND REVOLUTION FOLLOWING THE PRINTING OPERATION.