The card punch had a maximum rate of 150 cards per minute. Timing was quite critical throughout the operation of the card punch, the card reader and the printer, all being based on electromechanical principles. The basic card punch mechanism was manufactured by Bull, a French company which owned patents on 80 column punch card machines. The machine came in two versions, the P147 and the P67, the main difference being electromagnetic clutch or a solenoid operated mechanical "dog" clutch to initiate a punch cycle. Since many gears, electrical contact cams were affixed to the main shaft with taper pins, the P 67 with its severe stopping dog clutch would cause timing loss more frequently than the P 147. Most emergency maintenance time was spent replacing worn and damaged taper pins and retiming the machine. The card punch had a preread station, a punch station and a checkread station. The machine could be quite difficult to maintain and required much skill to troubleshoot and maintain. The machine cycle was oddly divided into 420 "points" or "Bull degrees".