Patent GB-749378-A (GB)
Title: Improvements in or relating to apparatus for use in statistical machines for controlling the movement of an angularly movable type-carrying member
Inventor: EXCELL ARTHUR WILLIAM
IPC: G06K15/04
Filed: 1953-05-27
Abstract: 749,378. Typewriters &c. POWERSSAMAS ACCOUNTING MACHINES, Ltd. May 6, 1954 [May 27, 1953], No. 14815/53. Class 100 (4). Apparatus for controlling movement of an angularly movable type-carrying member in a statistical machine comprises a support, an arm freely pivoted on the support, a member carried by the arm for movement therewith in an arcuate path, and a spring to control movement of the member away from the starting position wherein a first link is pivoted to an extension of the arm, a second link is pivoted about a fixed axis between the support and the arcuate path, and the spring is anchored to one link and to a fixed anchor to maintain a substantially constant torque. The type carrying member is in two parts 1, 2, Fig. 1, with type elements 3 supported on the part 1 (type sector). Part 2 is known as the gear sector and is provided with teeth 5 co-operating with a rack 6 forming part of an accumulator. The rear gear sector 4 is movable with the gear sector 2 to permit of a carry operation. A spring 7 retains normal relationship between sectors 2 and 4. The sectors 1, 2 are freely mounted on a spindle 8 in frames F. Sectors 1, 2 are movable angularly relative to one another for the purpose of type character selection, the sector 2 carries a latch 9 pivoted at 10 and urged by a leaf spring 11  into co-operation with one or other of three steps 12, 13, 14 on sector 1. A heel 15 is carried by the sector 2 for co-operation with one of the stops of the stop basket of the tabulator. Each type sector 1 is carried by an arm 24 integral therewith. A similar arm 25 connects sector 2 with spindle 8. The arm 24 is provided with an extension 26 which extends from the end opposite that by which the arm 24 is connected to the sector 1, and one end of a first link 27 is pivoted to the extension at 28. A second link 29 is pivoted on a spindle 30 supported by a comb member 31. The spindle 30 is located between the support 8 and the arcuate path in which the type-carrying member is moved. The first link 27 is articulated to the second link 29 by a pin 32 offset from a straight line 33 joining the centres of pivots 28, 30. 'The spring 23 is anchored at one end to a plate 34 fixed to the comb member 31, this anchorage being located between the support 8 and the arcuate path in which the type-carrying member is moved, and its other end is anchored to the second link 29 at a position 35 between the support 8 and the arcuate path in which the type-carrying member is moved. When the sector 1 is moved forward under the influence and control of spring 23, the second link 29 is rocked counterclockwise as viewed in Fig. 1, about its pivot 30 and at the same time the spring 23 is turning progressively shorter and therefore weaker. However, the leverage X, Fig. 2, is progressively increasing and by this means the torque exerted by spring 23 is maintained substantially constant. The typecarrying members are restored to the starting position in known manner by a positively operated restoring bar 36, Fig. 2, which is common to all type-carrying members.