1,055,977. Mechanical calculators. RICOH CO. Ltd. Sept. 24, 1963 [Sept. 25, 1962]. No. 37624/63. Heading G4B. The Specification describes a ten-key adding listing machine with particular reference to operation of the printing mechanism, totalling negative amounts, tens transfer by extending the travel of the differential rack and zero elimination. Number entry (Fig. 1).-The keys 2 set pins 11 and operate a slide 13 which rocks lever 14, disengaging the end 14a from zero pin 12 and permitting the carriage to stop. There are single, double and triple zero keys acting directly on the zero pins 12. Flange 17 forms the nine stop. After depression of an operation key a motor is started which rotates shaft 60. Cam 59 permits lever 56 to rotate clockwise and the differential racks 18 which are connected to print bars 37 are released to springs 44. Return of the racks is by the action of shaft 54, moved downwards by lever 56, on lugs 53 on the print bars. Function control.-Depression of a total key moves slide 71 (Fig. 6) rearwardly to engage the second tooth 74 and cams slide 75 to the left. A lever 78 is thus moved to the right so that arm 78b remains in contact with cam 81 whereas arm 78a contacts cam 80 on the main shaft. The electric motor is started and shaft 60 clutched to the motor shaft. The motion of f lever 78 is such that the totalizer cradle 49 is rocked so that pinions 45 are engaged with the racks on their upward stroke. Cam 89 (Fig. 1) rocks lever 36 which positions slides 26 as shown. Extended teeth on the pinions 45 contact the end 28 of slide 26 and arrest the racks at positions corresponding to the settings of the pinions. The totalizer is then disengaged from the racks which are returned. If the total is negative as a result of a previous subtraction operation there will have been a carry out of the highest order. A transfer (see below) moves the slide 26 rearwardly. The highest order slide has a lug 26a (Fig. 5, not shown) which on carry releases a lever 100 to a cam. Lever 102 is effectively integral with lever 100 and rotates a lever 105 which releases a ratchet 93 (see below for effect of this). Movement of lever 102 is possible because totalizer cradle 49 is in the position shown presenting subtractive pinions 46 to the racks and shaft 48 does not prevent movement of lever 107 which contacts lug 102a of lever 102. The lug 100b is used, it is stated, in known manner to introduce the carry into the lowest order of the totalizer. In a subtotal operation, the subtotal key does not cause movement of slide 75 and the ends 78a, 78b of lever 78 remain in contact with cam 80. In addition or subtraction slide 75 is moved one half step to the left because of the movement of the pin carriage. The subtotal key initiates an addition while the total key initiates a subtraction. In the latter case the first tooth of slide 74 is engaged by slide 73 and the slide is cammed to the left to disengage ratchet 93 which is connected to a lever 95 (Fig. 5) which is thus released to a cam 97. The other end 95a of lever 95 controls the position of totalizer cradle 49 and so presents the subtraction pinions 46 to the racks. Symbol printing.-There is a rack 111 (Fig. 6) associated with a symbol printing bar and connected to a stepped lug 110. Lug 75c on slide 75 engages the various steps of lug 110 depending on the operation to be performed. Zero elimination.-Just before print-time in each cycle a shaft 130 releases levers 131 to their springs 139 (Fig. 1). The levers can only move if no significant number has been entered in the associated order. No lever to the right of the highest order lever which does not move can move due to overlapping lugs 133. If a lever does move lug 133 engage lug 137 on the print hammer to prevent it being operated. Tens transfer.-Normally the downward travel of racks 18 is limited by the abutment of lug 27 on slide 26 with step 21 in an internal slot on the rack. A thickened tooth on either the add or subtract pinion can move the next higher order slide 26 rearwardly so that lug 27 is opposite step 21a. This gives the rack one extra unit of movement and increases by one the number entered into that order of the totalizer. Print hammer operation.-These are released to the springs by cam-actuated movement of shaft 129 which besides releasing the significant zero determining levers 131 also through levers (not shown) raises the common spring blade 42 from engagement with the hammers. The Specification also describes a non-add entry mechanism and there is also provision for repeated entry.