671,452. Typewriters &c. BRITISH TABULATING MACHINE CO., Ltd., and LAST, J. Sept. 11, 1947 [Sept. 19, 1946], No. 28163/46. Class 100 (iv). [Also in Group XXIV] A printing unit for accounting machines and of the kind in which a line of characters may be printed at one time, comprises a series of sideby-side members each bearing a number of in-. tegral type and movable to select a particular type, a set gear for each type member permanently coupled thereto, a positive coupling means individual to and engaged for a constant portion of each cycle with the set gear, and a continuously rotating positive driving means common to all the type members and engageable with the coupling means, impulse-operated selecting means individual to each type member being provided which is actuated at differential times to effect the engagement between the driving means and the coupling means to initiate a typeselecting movement and common means being provided to effect disengagement at a fixed instant in the cycle to terminate such movement; means other than the coupling means restore the type members to their unset positions. As shown, a series of closely-spaced typewheels 1, Fig. 1, is employed, each typewheel carrying the digits 0-9 and each pair of digits being separated by four alphabetical or other characters, the digits 10, 11 being included as other characters. The setting is controlled by electrical impulses derived from the sensing of "Hollerith " (Registered Trade Mark) cards, and the impulses corresponding to the index points 9-0, X, Y select the digit types 9-0, 10, 11 in that order. For intermediate characters other than 10, 11, second impulses corresponding to the 1, 0, X, Y index points are employed and respectively cause movement of the typewheel, additional to that due to a first impulse, of 1/5, 4/5, 4/5 and 2/5 of the pitch between two digits. Each typewheel 1 is in permanent engagement with its set gear 3 the teeth of which engage spaces 2 between the type. A continuously-rotating member 26 rotates the typewheel through a clutch 24 constructed as described in Specification 588,525, [Group XXIV], and a gear train 28, 29, 31, the clutch 24 being controlled by the impulses as described below. The shafts 218, 219 of the gear train are carried by a frame 30 pivoted about the clutch shaft 220 and oscillated by cams and gearing from the main shaft of the machine so that the gear 31 is engaged with the set gear just prior to the time the 9 index point would be sensed in each cycle and is disengaged just after the Y index point would be sensed. Each clutch comprises a wheel member and a ring member having teeth with circular scallops and connected by a spring which positions them relatively to one another so that the scallops do not coincide and so form a toothed gear engaged by the member 26. When a clutch pawl 21 and a check pawl 25 engage the ring and wheel respectively the scallops are caused to coincide, and the drive ceases. Normally the pawls 21, 25 are operative and the typewheels are stationary. The operation of the pawls by the impulses is as follows : -Sensing of a card hole causes an electric impulse to be delivered to an electromagnet 5 which attracts its armature 12 and leaves a member 13 free to rise under the action of a spring 18a connected to a lever 14 having a pin- and-slot connection with the member 13 and interlocking with the end 10a of a set lever 10 pivoted at 10b. The lever 10 has a tooth 9, and the release of the member 13 coincides with the arrival at the tooth of the corner 6 of a groove 7 in a continuously-rotating set-cam 8 which is common to all the type wheels and has a groove 7 corresponding to each index point. Also pivoted at 10b is an actuator 15 pivotally carrying a latch 16 held by a spring 18 in a shoulder 17 on the lever 10. When the tooth 9 drops into the groove 7, the end 19 of the lever 15 drops beneath the end of set latch 20 pivoted on the clutch pawl 21. As the trailing end of the groove moves the lever 10 about its pivot 10b, the end 19 is caused to be raised and thus lifts the latch 20 until its shoulder 32 engages the frame 33 under the action of a spring 22 as shown in Fig. 1A. At the same time, the clutch pawl 21 is moved out of engagement with the ring, and by its engagement with a projection 42 thereon also moves the check pawl 25 out of engagement with the wheel, so that the typewheel is driven from the member 26. The clutch is thrown out to terminate rotation of the typewheel by a knock-off cam 40 rotating in synchronism with the set cam 8, and provided with four lips 36-39. For all impulses corresponding to the 9-2 index points and for the impulse corresponding to the 1 index point when it is a first impulse, the leading lip 36 throws out the clutch by engaging a lip 35 on the latch 20 and releasing the shoulder 32 so that the pawls 21, 25 are brought into operation. For impulses at the O, X, Y index points, lips 37, 38, 39 respectively engage the lip 35 and terminate rotation of the typewheel. If the impulses at the O, X, Y points are second impulses, they cause restarting of the typewheel after the lip 36 has terminated movement due to a first impulse, and the typewheel receives a total movement equal to the sum of the two movements initiated by the two impulses. Should an impulse at the 1 index point be a second impulse, a delayed reengagement of the clutch is effected so that an additive movement of the typewheel of 1/5 digit pitch only is obtained. When such an impulse occurs, the tooth 9 enters the 1 groove in the cam 8 before the lip 36 causes re-engagement of the clutch pawl 21, and at the time when a link 43 pivoted to a lower extension of the clutch pawl is in the position shown in Fig. 1A where its foot 44 supports the tail 45 of a trailer 46 pivoted on the latch 16. At the same instant a lip 47 on a delay cam 48 engages the part 49 of the trailer 46 and thus prevents the latch 16 moving upward with the lever 10 and causes it to disengage from the shoulder 17. When the cam 48 clears the part 49, the actuator 15 moves anticlockwise under the action of spring 18 carrying the latch 16 with it and moving the end of the latch to the right beyond the shoulder 17. Thus when the lever 10 moves out of the groove 7, the shoulder 17 does not act on the latch 16 and the end 19 of the actuator is not moved upwards. Rotation of the knock-off cam 40 continues until lip 36 engages lip 35 to re-engage the clutch pawl 21, the end of the latch 20 then resting on the actuator end 19. Subsequent to this, the lip 47 of the delay cam 48 engages a leg 52 on the actuator 15 to raise the end 19 and disengage the clutch pawl 21 so allowing the typewheel to be driven. The rotation is terminated by the lip 37 of knock-off cam 40. Restoring typewheels to initial positions. Each set gear 3 bears a projection 58 situated in the path of a restoring arm 59 keyed to a shaft 57 upon which the gears 3 are rotatable. In advance of the earliest setting movement, the shaft 57 is rotated to move the arms 59 to the position 61, Fig. 1. After printing has taken place, the rotation of the shaft 57 is reversed and the arms 59 engage the projections 58 and move them back into contact with a stop comb 62 defining the unset position. To avoid shock to the moving parts, the shaft 68 of the comb is oscillated so that the comb moves anticlockwise, Fig. 1A, before the projections 58 reach it. When the projections reach the comb it is moving clockwise at such a speed that no shock occurs. Subsequently the comb is retarded to its rest position. Aligning for impression.-After the typewheels 1 have been set and the frame 30 has been rocked to disengage gears 3, 31, a bail 53, Fig. 1, is lowered to allow springs 54 to press aligning teeth 56 into the tooth spaces 2 in the typewheels. The bail 53 is lifted before the restoring arms 59 engage the projections 58. Hammer-impression arrangements.-A hammer 71, Figs. 1 and 11, is provided for each typewheel 1 and each has a lever 72 pivoted to its rear end and engaging the edge of an adjustable plate 77. A spring 67 attached to each lever 72, normally holds the parts 71, 72 in the position shown in Fig. 1 with the lever 72 resting against a vertical face 73 of the hammer. The hammers are cocked for printing by a cam 75 and, after release, move to the position shown in Fig. 11 to print, in which position the lever 72 and face 73 are separated. The spring 67 now acts to bring the parts back to their initial positions. The hammer blows are delivered against a steel strip 79 which prevents images of the hammers being produced on the paper 80. The hammer unit is supported by standards 186 pivoted at their lower ends so that the unit can be swung away from the type wheels to permit of the insertion of fresh sheets or a new ink ribbon 250. Paper-feeding arrangements.-The paper 80 is line-spaced by two driven rolls 81, 82, Figs. 1 and 8, co-operating with spring-pressed rolls 83, 84 respectively. The rolls 81, 82 haye gears 122, 123 meshing with a gear 120 integral with a ratchet wheel 121 engaged by a pawl 124 on an arm 116. A link 115 connects the arm 116 to a V-shaped member 113 pivoted at 196 and oscillated by a cam 112 attached to the end of the hammer cam 75. The effective stroke of the pawl 124 can be adjusted by means of an angularly movable mask 125 attached to an operating lever 126 and held in adjusted position by a spring-loaded plunger 127 engaging a notched sector 128. The roll 83 is in short lengths, each length being carried at its ends by brackets 85. These brackets are pivoted on a bar 87 and each pair is bridged by a plate 89 resting in slots 93 in the brackets and loaded at its centre by a spring 91. The roller 83 may be moved out of engagement with its driving roll 81 when desired by partial rotation of a shaft 97 having a V-notch engaged by a tooth 95 on each bracket in the operat