Patent GB-993676-A (GB)
IPC: G06C23/02
Abstract: 993,676. Positive clutches; Clutch control. ATVIDABERG-FACIT A.B. March 5, 1963 [March 3, 1962], No. 8733/63. Headings F2C and F2L. [Also in Division G4] The invention relates to declutching an operation shaft at the end of a repeater addition or subtraction so as to obviate what is stated to be a usual additional rotation. Gears 75, 79 (Fig. 2) are driven in opposed directions by continually rotating gears 74 and, by depression of a repeated addition or subtraction key 1 or 2 (Fig. 1), are selectively clutched to gear 58 which drives the operation shaft through gear 80. Release of the key causes declutching. Depression of an addition key 1 rocks a lever 12 about axis 14 causing part 12a to rock a vertical lever 16 clockwise. A lever 19 forms a toggle linkage with lever 25 and this is operated by lever 12 to rock a catch 23 upwards and a link 27 downwards. Catch 23 releases a cam-wheel 32 (Fig. 2), one of a set of starting cams 26, and a pawl 82 on the cam-wheel 32 which clutches the cams to a constantly driven gear 81. A cam 50 on cam-wheel 32 then rocks a threearmed lever 17 clockwise. One arm engages lever 16 and pulls it down so that for addition it rocks a lever 53 (see also Fig. 3) which through lever 55 operates a pawl 60 to clutch, through lug 79a, gear 79 to the gear 58. There is a similar pawl mechanism (shown in Fig. 2) on the other side of gear 58 for clutching the gear 58 to subtract drive gear 75. In this case the descending lever 16 will be caused by lever 13, operated by subtraction key 2, to engage lever 52. On each pawl is a pin 59a, 60a by which the pawl is actuated and which also extends through gear 58 to prevent both pawls being actuated simultaneously. The third arm of lever 17 engages a lever 33 to bring the lug 33a against cam 32 so that pawl 82 will be disengaged by the lug after about half a revolution of the starting cams. The operation shaft is positively located in stopped position by the arrangement shown in Fig. 7. A pair of discs 94, 95 embrace the shaft and are urged by a comcompression spring against a pin 96 on gear 80. A pair of scissors levers 72, 73 engage cutaways on the discs. When the levers diverge due to rocking of lever 44, the discs, and thus the operation shaft, are free to move. Conversely, when the levers converge they act as a locating brake on the shaft. When lever 33 is cammed to disengage pawl 82, levers 39, 42 (Fig. 2) and 44 (Fig. 7), to which lever 42 is connected by stud 44b, are rocked to operate the scissors levers. Lever 44 is rooked clear of slot 47a in lever 47 and rests on the edge of the lever. The operation shaft carries a cam 88 (Fig. 1) which rocks a lever 46 about shaft 22. The desired number of operations having been performed, the operation key is released causing link 27 to move upwardly into the path of the end of lever 46, which will then, through links 27 and 90, rock lever 47 so that lever 44 re-enters slot 47a. The scissors levers then converge to brake the operation shaft. Lever 44, through levers 42 and 39 (Fig. 2) also rocks lever 33 which, by its lower end, rocks a pair of catches 35 (Fig. 2) and 36 (Fig. 4, not shown) to disengage the appropriate clutch pawl 59 or 60. The upper end of lever 33 releases pawl 82 so that the starting cam mechanism rotates until after one halfrevolution it reaches its initial position where the pawl is disengaged by the catch 23 returned by release of the operation key.