297,717. Carpmael, M. H., (Royal Typewriter Co., Inc.). April 21, 1927. Adding and subtracting apparatus with several totalizers; attachments to typewriters. - In a computing-attachment designed primarily for billing purposes the items of a bill are typed and the amounts added to a column totalizer, whereupon the totalizer carriage is moved to bring a grand totalizer into the computing zone and an add and subtract lever is adjusted to the subtraction position so that on writing the total the column totalizer is cleared and the amount transferred to the grand totalizer. When printing totals if the column totalizer is not cleared, either by neglecting to move the reversing lever or by error in writing the amount, error-check mechanism is rendered operative to prevent return of the typewriter carriage. If a credit item is to be entered in the column totalizer the reversing lever is set to subtraction and unless the lever is returned to add position, after each entry, means are effective to prevent return of the carriage. Improvements are described in connection with full stroke devices for the actuators, key crowding locks, and means to disconnect automatically the computing mechanism from the numeral keys when the typewriter carriage is moved to the extreme right, or when it is desired to retype a figure in the computing zone. Attachment connections and actuation. The attachment comprises a casing 1, Figs. 1 and 2, having an upper plate 19 adapted to be secured to the typewriter frame by screws 20, 21, and a plate 15 extending from the base below the keyboard and secured to the frame by a screw 17 passing through a foot 16 and hole 18. The plate 15 has an extension 22 with up-turned ears 23 to which are pivoted levers 24 connected at one end by links 26 to the numeral key levers G and at the other end by links 28, Fig. 5, to toothed segments 30. Each segment 30 meshes with teeth 45 on a corresponding gear 42 loose on a shaft 44 and provided with teeth 46 varying in number according to the value of the key associated therewith and with cam surfaces 47, 48 disposed on opposite sides of the gear. The teeth 46 of the gears 42 co-operate with pinions 53 on a sleeve slidable. and rotatable on a shaft 50, the pinions 53 being normally out of the path of the teeth. Each pinion has a detent pawl 56 with a nose 58 normally out of engagement with its corresponding pinion 53 but rendered operative by the corresponding cam 47. The master wheels 61, Figs. 4, 5, and 25, for the two totalizers are carried on a sleeve 60 on a shaft 59 and are normally engaged by pawls 62 forming part of a frame 62 having a downwardly projecting arm 69, Fig. 13. The arm 69 carries a pin 71 with a crown gear 72 engaging a sector on a vertical spindle 74 supported in a bracket 79 and provided with an arm 80 engaging a recess between the end pinion 53 and an elongated pinion 52 on the end of the sleeve so as to move the pinions 53 into the path of movement of the gears 42 when the frame 63 is rocked. Add or subtract setting. The master wheels 61 are actuated in one direction or the other from the elongated pinion 52 through a reversing mechanism comprising pinions 84, 85, and 86, the pinions 84, 85 being integral with a sleeve on a short stud 82 and the pinion 86 integral with a sleeve on a stud 83. The sleeves on the studs are movable together by a lever 88, Fig. 14, engaging grooves thereon and operated by an add and subtract finger piece 92 integral with an ear on the upstanding arm 90 of the lever 88. Totalizers. The totalizers are mounted in a casing 99 slidable on rods 101, 102, Figs. 4, 5, and 23 carried by the casing 1 the casing being moved in a step by step manner, when the typewriter carriage is in a computing zone, by a pick-up dog 243, Fig. 1, on the carriage engaging a detent 106 on a rack 105, Fig. 5, carried in an inverted channel member 103 secured to the top plate 19. The rack 105 engages a pinion 107 adjustably secured to a shaft 108 on which is secured a pinion 115 engaging a rack 116 pivoted at one end to the casing 99. Each totalizer unit comprises a pinion 121, an intermediate gear 141, a geared numeral drum 137, and a Geneva-type transfer gear 125. The gears 125 are mounted on levers 123 pivoted at 124 to the casing and consist of their pinions 126, 126<1> with an interposed detent member 127 with depressions engaged by the spring fingers 131 of a plate 130. Full-stroke mechanism. A double comb member 145 with upper and lower tines 146, 147 is mounted on a shaft 144 to co-operate with the cams 48 of the gears 42. Depression of a key through the sector 30 rotates the gear 42 and the cam 48 rocks the member 145 clockwise, Fig. 5 so that the corresponding tine engages one of the indents on the cam to prevent return movement until the cam has been moved sufficiently to clear the tine whereupon the member 145 returns to normal position. On the return movement of the sector and key the member 145 is rocked in an anticlockwise direction and in a similar manner prevents a second actuation until the key has been completely restored. The shaft 144 carries at one end an arm 149, Fig. 22 with a roller 150 engaging the lower end of the arm 69 to operate the detent frame 63 and a pin 157, Fig. 10, on the arm 69 co-operates with a frame 153 similar to the frame 63 and with arms 154 having off-set ears 155 to restore the levers 123 to operative position after being displaced by pins 64 on the detents of the frame 63. The operative levers 123 are permitted to move by providing notches 188 in the rod 102 the remaining levers by engaging the rod being locked in engagement. The return movement of the member 145 is effected in one direction by the spring 65 controlling the frame 63 and in the opposite direction by a spring-controlled arm 159 engaging the roller 150. Keyboard locks. To prevent the depression of more than one key at a time the segments 30 are provided with projections 41, Figs. 5 and 27, adapted to pass between balls 38 supported by arms 37 on a plate 36 the balls being allowed sufficient play between end projections 39 to permit of the passage of one projection only. Non-add key. To enable a figure to be typed without actuating the computing mechanism a lever 170, Fig. 22 pivoted to the casing has its rear end underlying the roller 150 so that on depression it rocks the full-stroke member 145 out of operative position to prevent movement of the gears 153 into active position. The computing mechanism is also disconnected from the numeral keys when it has been moved to the extreme right by means of finger 173 carried by the totalizer casing engaging a lever 174 connected by a link 177 to an arm 178 co-operating with the roller 150 to move the member 145 as above described. The computing mechanism is also rendered inoperative by withdrawing the pick-up dog 243 from its engaging position. The dog 243 is spring-controlled and has its rear end 250, Figs. 28 and 29 engaging a cam portion of a finger 246 pivoted to the block 242 supporting the dog. Punctuation. When the totalizer carriage is standing opposite a decimal or comma position depression of a key is prevented by a rack 118, Fig. 26, with wide teeth 119 at intervals corresponding to the punctuation spaces. A pivoted lever 181, Fig. 7, with an angular projection 185 is adapted to be rocked by a. plate 186 engaged by a pin 187 on the frame 63 when the frame is operated so as to cause the cam tooth 184 on the lever to enter a tooth of the rack or be arrested bv a wide tooth 119 and in the latter case prevent release of the train of mechanism for operation. Error check mechanism. When the grand totalizer Teaches the computing zone and it is desired to clear the column totalizer, the reverse lever 92 is moved to subtract position, Fig. 14, and through its engagement with an ear 192 of a lever 189 effects a rocking of this lever, and through a link 217 causes a sliding movement of a feeler plate 210 to the left, the plate being mounted in ears on a U-shaped frame 212, Fig. 19, pivoted on a shaft passing through openings 214. The plate 210 is also shifted automatically by the connecton of the lever 189 through a link 203 with a cam arm 202 of a lever 199 engaged by the totalizer casing when moved to the computing zone for transferring amounts from column to grand totalizer. In the shifted position of the plate the narrow part 220 of an opening 219 therein engages one end of a bell-crank 222, and when the latter is rocked the plate 210 is raised to cause the upper edge thereon to enter notches 143 in the intermediate wheels 141 of the column totalizer which are aligned when the totalizer is cleared, so that movement of the plate is permitted. If the totalizer is not properly cleared, movement of the plate 210 and of the bell-crank 222 is arrested. The bell-crank 222 is connected by a link 229 to a lever '227 pivoted to the top plate 19 and on which'is pivoted at 230 a second lever 231. Also pivoted to the angular end 235 of the lever 227 is a bell-crank 237 with an ear 238 engaging a cam-surface 233 on the lever 231 and an ear 239 engaging the end of the lever 227. A lug 208, on the block 242 of the typewriter carriage, on the return of the carriage engages a cam surface 240 on the bell-crank 237 and rocks it about its pivot so as to cause the ear 238 to engage the cam surface 233 and rock the lever 231 to position its end 234 into the path of the stop 208 and prevent further movement of the carriage when the bell-crank 222 is arrested. The return of the carriage is also prevented when a credit item is entered in the column totalizer unless the reverse lever is first returned to add position since the setting of the lever to subtraction has shifted the plate 210 to the left. If the end of the bell-crank 222 lies within the large opening 219 of the plate 210 and so permits the bell-crank to oscillate, the lug 208 will cause the levers 227, 231 an