Patent GB-787069-A (GB)
Title: Improvements relating to sign detection mechanism for calculating machine registers
Inventor: HALL GEORGE VIRGIL
Filed: 1956-08-07
Abstract: 787,069. Calculating-apparatus. MONROE CALCULATING MACHINE CO. Aug. 7, 1956, No. 24191/56. Class 106 (1). A sign detection device for a crawl carry totalizer, which operates without moving the totalizer wheels into alignment, comprises switch contacts associated with the wheels and adapted to be serially connected under the control of a cam, or the equivalent, associated with each wheel, each such cam having a positive, zero and negative control zone. The device may control coloured lights or other indicating means for showing the condition of the totalizer, or may control machine operation at the zero pass of the totalizer during automatic division operations. In Figs. 1, 2 and 4, a cam 3 is secured to each totalizer wheel 1 and is formed with low, intermediate and high dwells 15, 16 and 17. A zero signifying contact 4 has a pin 8 bearing against the cam, and coacts with a centre contact 6 and a negative signifying contact 5. The contact 4 associated with the overflow order is connected to a lead 50, each contact 6 to the next lower contact 4 whilst all the contacts 5 are connected to a second lead 49, as shown in Fig. 1. With the totalizer standing at zero, the intermediate dwells of all the cams engage the pins 8 and close the contacts 4 and 6, but not the contacts 6 and 5. The leads 49 and 50 are therefore open-circuited. For positive registrations, the high dwell 17 of one or more of the cams 3 may engage its pin 8 and close contacts 4, 5 and 6. The circuit between the leads 49 and 50 will, however, remain broken, at least between the contacts 5 and 6 of the overflow order. For negative registrations, a circuit is completed between the leads 49 and 50 through the serially-connected contacts 4 and 6, and one or more contact pairs 5 and 6. Although the serial connection of contacts 4 and 6 becomes broken where the low dwell 15 reaches the pin 8, contact closure in higher orders will complete the circuit. A modified form, Fig. 7, distinguishes all three conditions of the totalizer by selective energization of positive, negative and zero signifying relays 66, 67 and 68 adapted, for example, to control coloured indicator lights. Each totalizer wheel cam 57 engages a pair of centre contacts 60, 63 adapted to change over from a zero signifying contact 58, 61 to a positive or negative signifying contact 59, 62. A circuit to the zero relay 68 is thus completed through all the contacts 58 and 61 when the totalizer is at zero, this circuit becoming broken when the totalizer registers a positive or negative amount, and a circuit to the positive relay 66 or negative relay 67 then becoming established through one or more of the contacts 59 or 62. Automatic division. The totalizer 1 of Figs. 1, 2 and 4 is carried by a shiftable machine carriage 19, Fig. 5, and the leads 49 and 50 are connected through brushes and contact rails i and 14 to a machine control magnet 12, the circuit also including master contacts 13 controlled by a cyclic cam 56. The contacts 4, 5 and 6 are housed in a casing 7 carried by a pivoted cradle 48 normally positioned so that the pins 8 are clear of the cams 3. Depression of the division key results in downward movement of a link 730 to rock a lever 52 clockwise and raise the cradle 48 to engage the pins 8 with their cams 3. The lever 52 also rocks a bail 54 to swing totalizer aligning levers 46 out of normal engagement with actuating snail cams 47, so that the totalizer wheels are not aligned during the progress of the division operation. When the zero pass is reached during a succession of subtractive cycles, the circuit of the control magnet 12 is closed through the leads 49 and 50, in the manner explained above, but is not completed through contacts 13 until near the end of the cycle, the contacts 13 re-opening in the full cycle position of cam 56. Operation of magnet 12 disengages a latch 31 from a pawl 25 on a pivoted stopping arm 24, the released pawl engaging behind a step 27 in a cyclically rocked arm 22. The arm 24 is thus swung clockwise, to terminate subtractive operation, and rebounds against a stop 29 to reset the pawl 25 and latch 31 in preparation for the ensuing corrective add cycle, when the magnet 12 is again energized to initiate the next subtractive phase. Specification 272,569, [Class 106 (i)], is referred to.