Patent GB-640347-A (GB)
Title: Improvements in or relating to calculating machines
IPC: G06C7/06
Filed: 1946-05-20
Abstract: 640,347. Calculating-apparatus. STEVENS, A. H. (Felt & Tarrant Manufacturing Co.). May 20, 1946, No. 15176. [Class 106 (i)] A " digit - key - responsive " power - driven calculating machine is provided with a driving clutch comprising a main driving-member, a connecting member engaged with the driving member to drive the calculating mechanism when any numeral key is depressed, and an auxiliary member arranged for a limited relative movement with respect to, the driving member and having cam means for urging the connecting member into full engagement with the main driving member. Depression of any numeral key 23, Fig. 1, operates a parallelmotion device comprising a bar 45 lowered by the keystem and pivoted to levers 48, 49 connected by a link 52 which is thus moved to the right. A dog 59 is pivoted to the bar 45 and is lowered to lower, through mechanism described below, a connecting member or hook 34 into engagement with a rotating driving- wheel 33, the hook then being pulled to the left to rock an arm 37 to which it is pivoted. The arm 37 moves to the left a link 36 which through a clutch 41 turns clockwise a segment 27. This latter is arrested differentially by the engagement of a projection on a slide 58 with the stem of the depressed key, the slide being connected to the segment by a link 56. The driving-wheel 33, Figs. 14, 17, comprises a main driving member or disc 120 having sloping arms 130 with rounded ends, and an auxiliary member or disc 121 having arms with cam ends 131. The auxiliary disc 121 can move slightly relatively to the main disc 120 against the action of a spring 128, the movement being limited by a pin-and-slot connection 126, 127. If the hook 34 when being lowered contacts the top slope of a cam end 131, the hook is lifted over the adjacent arm 130 on the main disc and then drops so as to be fully engaged by the next succeeding arm. If the hook is caught by an arm 130 when it is somewhat lower, the cam 131 assists in pulling down the hook into full engagement. A third possibility is the catching of the tip of the hook 34 by the tip of a cam 131. Full engagement is then ensured by the contact, as the hook is dragged to the left, of a shelf 97 on the hook with a projection 137 on an arm 133. The dog 59 is latched down by a latch 64, Fig. 2, pivoted on the link 52 and having a leg 67 which latches over an ear 68 of the dog, this latch being later released by the engagement of a pin 70 on the arm 37 with another leg 69 of the latch as the arm 37 completes its first or counterclockwise rocking movement. The dog 59 depresses a retaining lever 77 against the action of a spring 79. The hook 34 has a forked part 75 which rests on a shelf 76 projecting from the retaining lever 77. The hook does not drop upon the initial depression of the retaining lever 77 because it is held by a shelf 84 on a second lever 82 held by a spring 85. The downward movement of the retaining lever 77 tightens a torsion spring 86b, 86a and this eventually overcomes the spring 85 and lowers the hook 34 into engagement with the rotating wheel 33. The action-of the dog latch 64 is prevented by a projection 83 on the second lever 82 until the hook 34 is lowered, the dog 59 thus not being latched down unless the key is fully depressed. In order to delay the lowering of the hook 34 until the torsion spring 86b has been fully tensioned and thus to ensure that the hook moves rapidly irrespective of the speed of depression of the key, the time of lowering of the hook 34 is also controlled by a hook delay lever 88 which has a projection 95 which underlies a shelf 97 on the hook 34 until the delay lever 88 is rocked clockwise about its pivot 89. This rocking is effected by a pull lever 98, the end 103 of which engages the top 96 of the delay lever 88, the pull lever being pivoted to a bell-crank 100 carried on the link 52 which moves to the right as a key is depressed. The timing of this engagement is adjusted by rocking the bell-crank 100 by turning a pin 111 having an eccentric part engaging a slot in the bellcrank. The delay lever 88 is released and returned to active position by a spring 91 when the pull lever 98 is lifted by the pin 70 on the arm 37 during the first or counterclockwise rocking of the latter. The hook is lifted from engagement with the rotary wheel by a tooth of the latter contacting with a cam surface 138 on the hook. To ensure that the shelf 97 on the hook 34 is lifted back on to the projection 95, Fig. 2, of the hook delay lever 88 and a second premature operation prevented, as the hook is being disengaged the shelf 97 swings upwardly a guard lever 139 against spring action, a sloping part 141 of said lever later snapping behind the shelf 97 so that, when the hook 34 is restored to the right, the sloping part 141 lifts the shelf on to the projection 95. Specification 640,445 is referred to.