Patent GB-553198-A (GB)
Title: Improvements in or relating to calculating machines
IPC: G06C7/06
Filed: 1941-09-18
Abstract: 553,198. Calculating machines. STEVENS, A. H. (Felt and Tarrant Manufacturing Co.). Sept. 18, 1941, No. 11984. [Class 106 (i)] A calculating machine includes a segment lever for imparting digital actuation to an actuator, keys for differentially operating the segment lever and a key lock lever means controlled by said keys for limiting the movement of the segment lever to the selected digital degree of actuation, and means comprising an element mounted on one of the levers and coacting with the other lever whereby overthrow and resultant rebound of the key lock lever are prevented. The invention is applied to a duplex comptometer in which the mechanism is easily removable from the case which is lined with sound-deadening material 108. The cancelling-actuator handle 115 is generally of known type but is mounted within the casing and has a dust-excluding portion 117. Totalizer and transfer.-Segment lever 16 has rack teeth 19 meshing with pinion 20 forming part of an internal ratchet mechanism 22, Fig. 12 (not shown) which is effective on the upstroke of lever 16, in known manner, to clutch pinion 20 to lantern wheel 23 connected by gearing with numeral wheel 26. Gear 28, Fig. 9, winds up transfer motor spring 29 which has an enlarged loop 31 to equalize the tension, and which is connected to member 30, which has a stop of known construction adapted to be engaged in turn by two releasing detents. Member 30 carries a cam which operates lever 35 in known manner at transfer, so that pawl 36 moves lantern wheel 23 of the next higher denomination. Transfer can take place only when segment lever 16 is in its upper position. Transfer at any other time is prevented by a detaining latch tooth formed on the front of stop detent 38 pivotally mounted on transfer lever 35 and normally engaged by roller 40 of the next higher order so as not to engage the stop of member 30. On depression of the segment lever 16 of next higher order, roller 40 releases detent 38 to engage the stop on member 30 and prevent transfer The powerr stored in transfer springs 29 may be used to clear the. totalizer, in known manner. Lubricating means are provided in the lantern wheel assembly. Keyboard.-When a digital key 15 is depressed, a. shoulder (not. shown). on the key. stem first engages. a corresponding, projection 44 to depress key lock lever 43 a small amount. so that projection 45 rocks elbow, lever; 47 pivoted on lever 16, to. push link 52 forward to rock. links 56 counterclockwise- and in known manner release actuator hook 41 to. release. lever 16. Link 52 also depresses the pivotal point. 55 of lever 61, the forward end of which normally holds lever 65 in clockwise position to lock the totalizer mechanism. The key-stem shoulder then depresses levers. 16 and 43. together, and near the bottom of its stroke the key; according to whether it is odd or even, also depresses one or other of stop levers 71, 72 which depresses the forward end of lever 61 to release the totalizer lock and allow entry during; the returns movement of lever 16. Stop levers 71, 72 arrest the momentum of keys 15 and levers, 16 by depressing levers 74, 75 which have arms 78, which are swung forward so that pin: 79 engages one of teeth 80 on segment lever 16. Lever 16, lock lever 43 and stop levers 71, 72 are made of light-weight metal such as aluminium, and to relieve these parts of wear, stop bar 81 of steel is fastened to the: skeleton frame member of each denominational order and: has a number of shoulders 84 for en gaging the shoulders on the key stems at the end: of their downward movement Prevention of overthrow.-To prevent overthrow and rebound. of lock lever 43; it carries a pin 85, Fig.,. 11 extending laterally into recess 86 of lever 16 and contacting the lower edge when levers 43 and 16 are depressed.