Patent GB-425691-A (GB)
Title: Improvements in or relating to power operated typewriters
IPC: B41J23/06
Filed: 1933-09-20
Abstract: 425,691. Typewriters. BURROUGHS ADDING MACHINE CO., 6071, 2nd Boulevard, Detroit, Michigan, U.S.A. Sept. 20, 1933, No. 26003. Convention date, Oct. 24, 1932. [Class 100 (iv)] Relay type - lever actions.-In frontstrike actions com prising a universa bail adapted on de pression of the keys to be connected tc driving - means and the selected type lever, rapidity is in creased by arrang ing the universa bail and type-lever to be driven in im pression - making direction only and after being disconnected, to be returned rapidly and independently of the driving-means. The action may include means such as a cam-slot member for preventing the type-levers from rebounding from the normal position. The action may be associated with the power-operated caseshift and back-spacing mechanism described below. In the mechanism shown in Fig. 1, the type-lever 15 is connected to a bell-crank 20 having a cam-slot 21 co-operating with a roller 25 on a bell-crank 23 carrying a dog 30 which abuts on a rocking arm 34 operated by a key-lever. The dog co-operates with a universal bail 27 secured to a sleeve 54 which is mounted loosely on a continuously running driving-shaft 13. A ratchet-wheel 63 on the driving-shaft co-operates with a pawl 60 which is pivoted at 58 to a plate 57 secured to the universal bail. The pawl is urged towards the ratchet-wheel by a spring 61 connected to a pin 62 on the pawl, and a pin 80 on an arm 81 which is pivoted at 82 to the plate 57. The arm is formed with fingers 83, 84 which normally engage a pin 75 on the plate 57, and a stationary stop 89 respectively. The pawl is normally held in disengaged position by a spring-urged detent 65 which is pivoted on the framework, and engages a shoulder 7 on a rocking arm 72. A rocking arm 76, carrying the arm 72, is connected by a link 78 to a universal bail 50 co-operating with a pivoted hook 48 on the arm 34. On depression of the key-lever, the dog 30 engages the universal bail 27, the arm 72 is lifted by the universal bail 50, the detent is released, the pawl engages the ratchet-wheel, the universal bail 27 is rocked upwardly, and the typelever is swung for impression. During these movements, the arm 72 is moved forwards by co-operation of an incline 90 thereon with the pin 75, and the detent is permitted to return to normal position. Slightly before impression is effected, the finger 84 strikes an adjustable stop, and causes the finger 83 to strike the pin 62. The pawl is thereby knocked out of engagement with the ratchet-wheel, and the spring 61 passes above the pivot 58 and holds the pawl disengaged. Thereupon, the bail 27 is returned by a spring, the finger 84 engages the stop 89, and the spring 61 causes the pawl to re-engage the detent. Repeat impressions do not occur if the key-lever is held down, since the arm 72 is released by means of the incline 90 and cannot release the detent until the key-lever is released and again depressed. Additional or alternative means for the purpose consists of a pin 91 on the bell-crank 23 and a co-operating incline 92 on the hook 48, the arrangement effecting release of the bail 50 and permitting it to return to normal position. If the pin 91 and incline 92 are omitted, the hook may be integral with the arm 34. The type-lever is returned by means of a strong spring 26 arranged between the bell-cranks 20, 23. To prevent rebound of the type-lever, the cam-slot 21 is formed with a rear part 100 which is substantially concentric with the axis 24 of the bell-crank 23, the arrangement causing the bell-crank 23 to ease the final part of the return movement and to prevent movement of the bell-crank 20 when the parts have returned to normal position. The bell-crank 23 has a finger 114 for operating a letterspacing universal bar. Relay case-shift mechanism; shift - key actions.-The shift-mechanism is operated and returned by power means. The type-lever segment 120, Fig. 4, is secured to a plate 132 which is connected to a balancing-spring 128, and is provided with rollers 123, 124, engaging guide-rods 125. A link 131 connects the plate to an arm 133 on a shaft 134 provided with a bell-crank 135 having a V-head 136 which co-operates with a spring-urged detent 138 to hold the segment in either normal or shift position. A pawl 141 pivoted on the bell-crank is formed with teeth 143, 144 for co-operation with a ratchet-wheel 142 on the driving-shaft 13. Rocking movement of the pawl is limited by engagement of the walls 145, 146 of a slot therein with a collar 147 on the driving-shaft. The pawl is connected by a link 150 to a pivoted block 151 engaging a stud 154 on a spring-urged arm 155 pivoted on a bell-crank 157 which is connected by a link 162 to the shift-key lever. Normally, the stud 154 is below the pivot 152 of the block, and the wall 145 abuts on the collar 147. On depression of the shift-key, the stud 154 is raised above the pivot 152, the pawl is rocked forwardly to bring the tooth 144 into engagement with the ratchet-wheel, and the segment is depressed for case-shift. The wall 146 co-operates with the collar 147 to release the tooth at the end of the movement. The segment remains in shift position as long as the shift-key is held in depressed position. On release of the shift-key, the pawl is rocked rearwardly to bring the tooth 143 into engagement with the ratchet-wheel, and the segment is restored to normal position, the wall 145 co-operating with the collar 147 to release the tooth at the end of the movement. A shift-lock key-lever co-operates with a stud on the link 162 and has a stud for engaging a latch which is releasable by depressing the shift-key lever. Relay back-spacing mechanism.-On depression of the back-spacing key, a spring is initially tensioned and is then permitted to move quickly a member for connecting the back-spacing mechanism to the driving-means, the arrangement preventing chattering. A back-spacing pawl 180, Fig. 6, co-operating with a rack 181 on the carriage is connected to a link 182 having a tooth 186 for engaging the ratchet-wheel 142 on the driving-shaft. A stud 190 on the link is in the path of the shoulder 191 on an arm 192 which has pin- and slot mounting 193 on a bell-crank connected to the back-spacing key. An inclined shoulder 202 on the arm 192 normally abuts on a stud 203. On depression of the backspacing key, the arm 192 is detained momentarily by the stud 203, and is then snapped upwards by a spring in connection with the bell-crank that supports the arm. Thereby, the link 182 is snapped upwards to effect engagement of the tooth 186 with the ratchetwheel, the snap-action preventing chattering. The ratchet-wheel carries therewith the link to effect back-spacing and at the end of the movement, the ratchet-wheel strikes a lug 201 on the link and disengages the tooth 186. When the tooth is disengaged, the stud 190 is located below the shoulder 191 and repeat operation is thereby prevented.