Patent GB-600485-A (GB)
Abstract: 600,485. Calculating-machines. STEVENS, A. H. (Felt & Tarrant Manufacturing Co.). June 22, 1945, No. 15944. [Class 106 (i)] To obviate unwanted transfers during subtraction by complementary addition, transfer-inhibiting mechanism is conditioned for operation by a subtract or other control key and is subsequently operated in response to the depression of a digit key in the highest denomination of the subtrahend to inhibit the transfer between that denomination and the one above it. The invention is shown as applied to a key-responsive independently-operated machine of the kind disclosed in Specification 601,375. The add and subtract keys 87, 88, Fig. 3, are connected to a beam 91 pivoted at 92, depression of the subtract key 88 rocking the beam to rock clockwise, through a resilient connection a coupling shaft 95 carrying for each denomination an arm 112, Fig. 4, linked to a bar 114 pivoted to an inhibiting lever 115, 116, controlling the transfer pawl. in the next higher denomination. Each bar 114 is thus lifted to bring a projection thereon into the path of a projection 118, Fig. 2, on a denominational link 55 which is shifted to the right upon the depression of any digit key 24 in that denomination. The highest digit of the subtrahend is entered first, the link 55 in that denomination thus being shifted first to rock anticlockwise, through the projection 118, the corresponding transfer-inhibiting lever 115, 116, the end 121 of this lever engaging the end 122 of the next higher transfer pawl 41 whereby this pawl is swung anticlockwise to inactive position and is there latched by a latch 127. The entry of the set digit now occurs by known means including an actuating link 59 which is shifted to the left by a motor-driven shaft 45. During this shifting, a stud 124 on the actuating link 59 engages an arm 112 to restore anticlockwise the coupling shaft 95 whereby all the bars 114 are returned to normal positions and the operated inhibiting lever is retracted by a spring 123. Transfer is thus inhibited only in the one desired denomination. The restoration of the coupling shaft 95 restores the subtract key 88 and depresses the add key 87. Normally transfer is effected by the clockwise rocking of a transfer lever 39 in which the transfer pawl 41 is pivoted, the pawl thus being caused to engage and advance a lantern pinion 28 in the higher denomination. When the machine attempts to transfer through the inhibited position, the rocking of the transfer lever 39 brings the transfer pawl latch 127 into contact with an arm 131 on a normally stationary correcting shaft 132 whereby the latch releases the transfer pawl which is then reset by spring action. Correcting errors. A transfer pawl 41, Fig. 2, which has been moved to inactive position may be released by operation of the zeroizing lever which, inter alia, rocks clockwise the correcting shaft 132 so that the arms 131 rock the pawl latches 127 to free these latches. Interlock. When actuation has commenced in any denomination, the projections 118, Fig. 2, have moved over the bars 114 so that the latter cannot be raised to condition the inhibiting mechanism. Specifications 148,292 and 154,603, [both in Class 106 (i)], also are referred to.