of the punched card. Using the impulse from the ‘contact roll’ / ‘card brush’ / ‘wire contact relay’ circuitry, a ‘push rod’ would latch (stop) the individual ‘lifter bar’ on its downward motion with the character to be printed correctly positioned on the print wheel and facing 1 of 60 ‘print hammers’. An ‘alignment bail’ would then seat itself in between the teeth of the ‘print wheels’ to perform vertical alignment. A ‘card shield’ would grab the punched card to hold it in place and lower it a position almost touching the inked print ribbon and print wheel. At the correct time 60 ‘hammers’, under spring tension and controlled by a cam, would ‘fire’ pressing the card / inked ribbon onto the print wheel and leaving an inked impression of the character on the surface of the punched card. There is a blank space on the print wheel for non-printing columns. The printed card is then released by the ‘print shield’ into the ‘transport belts’ and moved to the stacker. The 557 was prone to jamming of the lifter bars and resulted in what the CEs called a "rack and wheel" job. This meant stripping the machine down to its base and rebuilding it, an eight-hour job. See also Unit record equipment IBM 550 Numeric Interpreter References IBM 557 Alphabetic Interpreter Reference Manual A24-0516-1 External links photo 557 557