783,871. Calculating apparatus. BURROUGHS CORPORATI(DN. Dec. 10, 1954, No. 35841/54. Class 106 (1). Totalizer engagement timing mechanism of a calculating apparatus comprises a pair of engagement actuator elements, at either end of the path of a cyclically reciprocated operating member, and settable control means adapted to place these actuating elements selectively in or out of the path of the operating member according to the set machine function. The invention is applied to the accounting machine described in Specification 783,869, which has a cyclic operating member 20 adapted to be reciprocated longitudinally of the machine forwardly from its normal rearward position shown. The operating member 20 is fitted with a cam 43 for engagement with the actuator elements which comprise pairs of bell-crank rockers 50, 51 and 52, 53 pivotally mounted on either side of a frame plate S, the pair 50, 51, Fig. 2, effecting totalizer engagement in add timing and the pair 52, 53, Fig. 1, in total-taking timing. Addition.-The rockers 50, 51 are pivoted with lateral play on studs 54, Fig. 11, and with springs 55 urging them up to the plate S, so that bevelled ends 45, 47 of the cam 43 can cant them laterally and clear. A pair of displacement levers 111, 113, connected by a link 116, are also adapted to cant them clear of the cam 43 but are ineffective during add operations. Similar displacement levers 107, 102 for the rockers 52, 53, Fig. 1, are, however, effective to hold these rockers clear and inactive. The cam 43 is formed with converging cam surfaces 48, 49 in its upper face, the rearmost rocker 51 normally engaging between these surfaces (see Fig. 2). Immediately the cam commences its forward cyclic movement, the surface 49 cams the rocker 51 counterclockwise and the hooked end of a link 63 connected with the rocker pivots a totalizer engagement lever 24 clockwise to disengage the totalizer. As the cam 43 reaches its forward position, it enters into similar engagement with the rocker 50, its bevelled end first canting the rocker clear without actuating it. At the commencement of the return movement, the surface 58 similarly cams the rocker 50 clockwise so that the hooked end of a link 74 connected to this rocker 50 returns the totalizer engagement lever 24 counterclockwise to engage the totalizer. This position is maintained throughout the return movement, at the conclusion of which the cam re-engages the rocker 51. Total-taking.-The total-taking rockers 52 and 53 on the reverse face, Fig. 1, of the plate S are similarly constructed but their hooked links 100, 92 are arranged to have a reverse action on the totalizer engagement lever 24 so that, when both are operative, the totalizer is engaged during the forward stroke of the cam and disengaged on its return. Depression of the subtotal key actuates the displacement levers 111, 113 to cant the add rockers 50, 51 clear of the cam 43, and also the displacement lever 107 to release the total rocker 52 into the path of the cam. The rocker 52 is consequently actuated at the commencement of the forward stroke of the cam to engage the totalizer, and the totalizer remains engaged throughout the cycle. Depression of the total key results in the same action except that a hooked link 163 is rendered effective to couple the displacement lever 102 with the lever 107, so that both the rockers 52 and 53 are released into the path of the cam for actuation thereby. As a result the totalizer is disengaged at the end of the forward stroke of the cam and remains disengaged for the rest of the cycle. Non-add.-By providing a disengageable coupling, similar to the hooked link 163, between the displacement levers 111 and 113, the rocker 51 can be rendered effective alone so that the totalizer is disengaged for the complete cycle. Subtraction.-The totalizer 21, Fig. 4, is engageable alternatively with upper add racks 22 or lower subtract racks 23. The totalizer engagement lever 24 is connected to a throw link 27 having slots 32 alternatively engageable with studs 30, 31 on a pivoted disc 29 carrying a pendant end support 33 for the totalizer. Normally, the lower slot 32 engages the stud 31 so that clockwise movement of the lever 24 results in upward movement of the totalizer to engage the add racks 22. Operation of a subtract lever 38 raises the link 27 for the upper slot 32 to engage the stud 30, as shown, and the totalizer is then lowered to engage the subtract racks 23 when the lever 24 is actuated.