Patent GB-809523-A (GB)
Title: Ten key adding and subtracting machine
IPC: G06C7/08
Filed: 1956-11-30
Abstract: 809,523. Calculating-apparatus. UNDERWOOD CORPORATION. Nov. 30, 1956 [Dec. 12, 1955], No. 36646/56. Class 106 (1). [Also in Group XVI] A calculating machine which effects subtraction by engaging the totalizer with differential actuators during their outward stroke instead of during their return stroke has one control member which causes the machine to perform addition or subtotal-taking according to whether an amount has been set for that operation or not, and another control member which causes the machine to perform subtraction or total-taking according to whether an amount has been set or not. Driving mechanism. Control keys.-Depression of any one of the control keys 60, 61 or 62, Fig. 7, rocks a plate 65, Fig. 11, about pivots 66. The plate 65 rocks a bent plate 52 about a pivot formed by its bend and a projection 58 of the plate 52 is withdrawn from a wheel 46 on a camshaft 48 rotated through one revolution by a pinion 45 in turn driven through a clutch 40 engaged by lateral movement of the shaft 37 under the action of the plate 52. The plate 65 is also rocked by a transversely-movable slide when the Add key 63 is depressed. The latter is mounted on spring arms 68. Key setting mechanism.-The stems of the amount keys have portions arranged in a row above that denominational row of pins 98, Figs. 2 and 6, of a pin-carriage 96 in setting position. The pin-carriage has no " 9 " pins but a fixed stop plate 156 in the " 9 " position. It is slidable laterally on rods 95. Each key-stem also has a portion arranged to rock a bail 92 carrying an escapement pawl 101 which co-operates with a rack 102 fast with the pin-carriage to cause the latter to be moved laterally one step by a spring 99 each time a key is depressed. As the pin-carriage 96 moves leftwardly, an arm 108, Fig. 9, is rocked by a link 107 and carries with it a plate 111. Towards the end of a cycle, a cam strikes an ear 119 of the plate 111 and so restores the carriage, the set pins being re-set by a cam plate 122. As the cam leaves the ear 119 the carriage moves slightly leftwardly to abut the end tooth of its rack 102 against the escapement pawl 101. Repeat mechanism.-If a repeat key 60 is depressed, a lever 125 is rocked to raise the plate 111 and so uncouple it from the arm 108. Thus, when the plate 111 is rocked by its cam as described above, the pin-carriage will not be restored. The lever 125 is temporarily latched after depression of the key 60 by lateral movement under the action of a spring 126 into engagement with a pin 128. However, rocking of the plate 111 restores the lever 125 laterally so that it returns to its initial position. Differential mechanism.-Combined actuators and type bars 132, Fig. 2, are guided by a plate 134 and a bar 135 and are urged rearwardly by springs 138 under the control of a bar 140 guided by slots in side walls and actuated by a shaft 144 oscillated by a cam. A short dwell in the zero position of the type bars occurs in both directions of movement. The type bars are arrested by the set pins of the pin-carriage or, in the case of any higher orders in which no digit has been set, by a bar 157 carried by the pincarriage. Immediately prior to the printing operation, an aligner bar 159 is rocked by cam means into engagement with teeth on the type bars. Correction cycle.-In a cycle initiated by the Correction key 62, the pin-carriage will be restored in normal manner. Moreover, depression of the key 62 moves a plunger into the path of the bar 140 controlling the actuators and so prevents any effective movement of the latter. The slight movement permitted to the bar 140 releases a latch for the blocking plunger which is freed again when the bar 140 is fully restored at the end of the cycle. Printing mechanism.-Printing is effected on a paper tape 184, Fig. 1, which passes from a rear spool around a roller platen 178 and between a table 195, Fig. 2, and a tear-off plate 196. The tape is guided round the platen by a guide 189 and is engaged by pressure rolls 190. The platen is mounted between arms 180 on a shaft 181 which is rocked by a cam to effect printing by raising the platen against the type bars, an ink-ribbon being interposed. A leaf spring 224 is formed with fingers arranged to bear individually against the type bars to ensure even impressions. A pawl 199 engages a ratchet wheel 198 to line-space the paper tape as the platen is restored after printing. Ink - ribbon mechanism.-The ink - ribbon passes between spools 203 mounted on the two arms 180 respectively and over guides 209 and 211, so as to extend along the platen. The ribbon is fed in one direction or the other by pawls 214, 215, respectively, on a shaft 212. As shown, the pawl 214 is effective to advance it one step each time the arms 180 carrying the platen and ribbon spools are restored. However, when the spool associated with the pawl 214 is nearly full, a feeler arm 218 coupled to the pawl 214 by a spring passes a dead-centre position and rocks the pawl 214 to an ineffective position and the pawl 215 to an effective position so as to reverse the drive. Addition.-The totalizer wheels 226, Fig. 2, are carried on a shaft in a frame 229 pivoted on studs 230, Fig. 1, and are engaged by detent spring fingers 241. The wheels are normally disengaged from the actuator racks 132 but the frame may be rocked to engage them with the racks by a link 232 under the control of a lever 235 which follows a cam 84, Fig. 4. Normally a pin 246 in the lever 235 is engaged in a hole in a follower 245 for a cam 83. In addition, cam 84 releases the lever 235 but cam 83 co-operates with the follower 245 to maintain the totalizer disengaged during the first half of the cycle. Then the follower 245 is released also and a spring 237 actuates the link 232 to engage the totalizer during the return stroke. Subtraction.-Depression of the Subtraction key 61, Fig. 4, cams laterally an arm 252 which shifts the follower 245 from the cam 83 to a cam 82, which causes the totalizer to be engaged during the first half of the cycle when the actuators are moving from zero to differential positions. Transfer mechanism.-At transfer, a widened tooth on the totalizer wheel engages an offset projection 267, Fig. 18, of a transfer arm 258 and rocks the arm slightly from a central position in one direction or the other according to whether addition (as shown) or subtraction is being performed. A pin 261 in a lever 263 pivoted on a rod 231 in the totalizer frame and urged upwardly by a spring is thus moved from a central detent notch into one of two diverging arms. The levers 263 abut spring fingers 270 on a plate 269 having ears pivoted on the rod 231. One of these ears carries a stud 272 which co-operates with a fixed cam surface 273 so that as the totalizer frame is rocked about the studs 230 to disengage the totalizer from its actuator racks, the plate 269 is free to rock counter-clockwise within the totalizer frame from the position shown. The levers 263 co-operating with transfer arms 258 which have been slightly rocked from their centre positions are then able to rock upwardly and their studs 261 cam the transfer arms 258 through an angle sufficient to cause teeth 266 to advance the next higher order totalizer wheels by one step. Each transfer arm 258 has two teeth effective in addition and subtraction respectively to advance the totalizer wheel in the appropriate direction. Towards the end of the cycle, a camoperated arm restores the plate 269 which returns the levers 263 and consequently the arms 258 to their normal positions. The totalizer wheels which have received transfers are at this time moved slightly, but are returned by their detents. Total-taking.-If the Subtract key 61 is depressed when no amount has been set, a totaltaking operation ensues, the timing of the totalizer-engaging mechanism being the same for the two operations. If no amount has been set, the pin-carriage is in its initial position and an ear of the zero stop bar 157 is positioned over an arm rocked by depression of the subtract key. In these circumstances therefore, the bar 157 is rocked to release the actuators. The actuators are stopped when the respective totalizer wheels reach zero position in which they are arrested by the abutment of their wide transfer teeth against the fingers of a slotted bail 288, Fig. 2, lowered against springs for this purpose. This lowering occurs only when no amount is set, the pin-carriage when moving back to its initial position camming a linkage, Fig. 24 (not shown), to lower an arm 303, Fig. 1, so that a rear portion of it is placed in the path of a stud 290 in a rear extension of the bail 288. Thus, when the totalizer frame is rocked to engage the totalizer, the bail 288 is moved to effective position. Zero-suspression mechanism.-In total-taking, zeros in orders higher than the highest significant digit, other than the two lowermost orders, are not printed. For this purpose, a lever 309, Fig. 2, is associated with each totalizer wheel and its upper arm drops into a notch in the hub of the wheel when the latter is in zero position so that the rear end drops into the path of a projection 306 on the side of the actuator rack to arrest the latter before the zero-printing position is reached. The levers 309 have overlapping ears so that all levers in orders below the highest significant digit will be raised by the lever of that order to allow their actuators to move to the zero-printing position. The highest order lever 309 is connected to the arm 303 which, as described above, is lowered in total-taking operations only. Thus, except in such operations, the highest order lever 309, and consequently all of the levers 309, will be raised to ineffective positions. Sub-total-taking.-Depression of the Add key 63 when no amount is set results.in a sub-total operation. The pin-carriage when in its initial position conditions a linkage, Fig. 24 (not sh