124,693. Wade, H., (Burroughs Adding Machine Co.). Jan. 2, 1918. Adding-apparatus with operating-means; selecting denominations; error keys.-Relates to single bank key-set independently-operated adding machines as described in Specification 124,538, in which machine the amount keys serve to set a field of stop pins in uniform series, one series for each denomination, mounted in a movable carriage traversed step by step relatively to the differential rack bars as the successive digits of an item are set up by depression of the amount keys, and after an item has been so set up, the carriage has to be restored to normal position with all its stop pins withdrawn. According to the present invention, the carriage is restored by a spring which is tensioned by the initial stroke of the main operating handle of the machine, but is held by a detent and does not operate until the detent is tripped near the conclusion of the return stroke of the main operating handle; the carriage can also be restored by an arm operated by an error key. The back plate 17<a>, Figs. 1 and 2, of the carriage has projecting from it a stud 17g with which is adapted to engage a pawl 60, Fig. 5. This pawl, which is forked and acted upon by a spring 60<b>, as shown, is pivoted to the top of the pivoted arm 61. In the position shown in Fig. 2, the pawl 60 is lowered from the stud 17g by means of the fork 60<a> engaging a stud 2a on the framework. Pivoted on the same axis as the lever 61 is a bell-crank lever 63, one arm of which engages a stud 61<a> on the lever 61. A spring 64 connects this stud to the framework. Upon operation of the main handle of the machine, the bell-crank 63 is moved to the right (Fig. 2) and moves the arm 61 tensioning the spring 64. The pawl 60 passes under the stud 17g and springs up behind to engage it on the return stroke. The arm 61 does not return with the bell-crank as the carriage is held by a detent 72 which is tripped near the completion of the return movement of the main handle. The detent mechanism is as follows. A spring 73, Fig. 1, tends to rotate a rock-shaft 71 carrying a pawl 72 adapted to engage a rack 70 standing off from the carriage. A full-stroke sector 69 connected to the main operating handle upon movement in the forward direction, moves, by means of a link 67 a bell-crank 66 connected by a twisted link 65 to the bell-crank 63, and a stud 66<a> on the bell-crank 66 moves away from a bell-crank 77 which engages a stud 74 on an arm attached to the rock-shaft, and allows the spring 73 to cause engagement of the detent 72 with its rack. When the return movement of the main handle is almost completed, the stud 66a engages the lever 77 and releases the detent, the spring 64 snapping the carriage home against the influence of a spring 40. An arm 90 carried by a shaft 91 is adapted to engage the stud 17g and move the carriage back to normal when the error key is operated. In returning the carriage, the projected stops engage a fixed cam plate and are withdrawn.