Columbian Press
The Columbian Press differs from the Albion Press chiefly in the nature of the levers which give the impression. The pulling bar is elbowed, and there is a diagonal connecting rod. The rod changes the horizontal movement of the bar into a vertical one by a link connected with the head, which itself becomes a powerful lever. The platen is attached to this by a strong iron bar, the descent being made steady and regular by two iron girders, which project from the cheek. The Stanhope levers are adopted in principle, but their power is greatly increased by the mode in which the long arm is brought down by the rod. The eagle at the top is a weight to cause the platen to rise again after the impression has been effected.
Described in fuller detail, these arrangements are as follows :-
At the top of the frame there is bolted to one of the uprights a heavy lever called the beam — the ornamental crosspiece shown in the engraving. It is kept in position by the counterpoise lever on which is placed the eagle. To the heavy lever in the centre is attached the piston, and to this latter, at the lower end, is bolted the platen. This is perfectly level on its under surface, but the upper part is strengthened by ribs or plates radiating from the centre. The spaces between the plates are called the tills.
The broad heavy lever at the top is, by a piece of iron called a link, joined at one end to another lever of angular shape. From the other end of this angular lever proceeds a straight iron bar called a connecting rod, which is joined at the other end by a pin to the bar handle. This handle is fixed to the upright of the press, seen at the left in the engraving. When it is pulled toward the pressman, it pulls the connecting rod with the angular lever forward also, thereby making the lever turn downward on its bolt. In doing this the main lever at the top is depressed at the same time, and consequently the connected piston and platen descend also, causing the impression.
When the handle is allowed to return, two heavy counterpoise levers, one at the head and the other behind the press, cause the heavy lever to ascend again.
Regulation of Power – The connecting rod between the bar handle and the lever is in two parts, fitting into a wormed socket. The rod can be extended by turning round one part in its screwed socket, first removing the pin attaching it to the handle. If screwed further in, it shortens the distance between the two parts, and increases the pull. if screwed outwards, an opposite effect is produced. A screw situated in the cheek or frame of the press can also be used to increase or diminish the distance the bar handle itself has to travel, thus increasing or decreasing the pull.