Patent GB-484062-A (GB)
Title: Improvements in and relating to power-driven type-writing machines
IPC: B41J5/22
Filed: 1937-09-21
Abstract: 484,062. Typewriters. UNDERWOOD ELLIOTT FISHER CO. Sept. 21, 1937, No. 25562. Convention date, Dec. 5, 1936. [Class 100 (iv)] Relay type - lever actions.-Each type lever is connected by action - linkage to a normally-flexed toggle, depression of a key-lever straightening the toggle and causing a pawl on one of the toggle-links to engage a toothed driving-shaft and transmit thrust through the straightened toggle to the action-linkage. To prevent thrust from being transmitted to the pawlpivot, the pawl, after a short free movement, may be arranged to abut on a surface on the link that carries the pawl. The action shown in Fig. 3 is mounted on a type-carriage 15 which travels for letter-spacing on a line-spacing carriage 14 arranged above a flat platen 10. The action comprises down-strike type-levers 45 each connected by linkage 51 .. 57 to a lever 58 associated with a key-lever 19 having a vertical arm 19a which enters a guide-slot 24 in a plate 25 and is connected to a returning-spring 27. A link 28, connected to the arm 19a by a pin-and-fork 30 and a spring 31, is formed with a hook engaging a pin 32 on a thrust-link 40 which is guided by a slot 87 in a plate 84. The link 40 is pivoted at 80 to a rock-arm 75 pivoted at 74 to a connecting-link 70 which is pivoted at 71 to the lever 58. The toggle formed by the links 40, 70 is normally flexed by means of a spring 85 connected to the arm 19a and link 40. A pawl 81 is mounted on a pivot 82 on the link 50 and is formed with a lug 88 having two teeth 88a for cooperation with a toothed driving-shaft 130. The pawl has slight pivotal freedom limited by contact of the lug 88 with the front of the link or a shoulder 90 thereon. On depression of the key-lever, the link 28 pulls the link 40 into alignment with the link 70 and causes the lower tooth of the pawl to engage the shaft 130. The pawl is thereupon rocked downwards to seat the lug 88 on the shoulder 90 and to disengage and engage the lower and upper teeth. The links 40, 70 are then thrust downwards and transmit a blow to the lever 58, thereby causing the type-lever to swing downwards. During transmission of the blow, the links remain aligned, the link 40 co-operating with a finger 94 on the plate 25 to maintain alignment during the final part of the movement. The shoulder 90 prevents the blow from being transmitted to the pawl-pivot 82. Shortly before the typelever strikes the platen, the pawl runs out of engagement with the driving-shaft, the remainder of the movement of the type-lever and linkage being performed by momentum. The spring 85 rocks the pawl away from the driving-shaft during return of the type-lever and linkage by means of a spring 48. The pawl is returned to normal position by striking the plate 84. If the operator holds down the key-lever, the link 28 drops to the bottom of the slot 87 and is returned by the pin 32 when the link 40 returns, repeat action being prevented since the hook on the link 28 cannot engage the pin until the key-lever is returned by the spring 27. A crowding-ball interlock 96 for the links 40 prevents operation of more than one type-lever at a time. When any of the links 40 are obstructed by the interlock, the springs 31 of the associated links 28 yield. To provide uniform touch and dip for the keys, the guide-slots 24 for the key-lever arms 19a are of graded lengths and the returning- springs 27 have graded tensions. The driving- shaft 130 is mounted on the type-carriage 15 and is connected by a belt to a pulley splined on a motor-driven shaft which is mounted on the line-spacing carriage 14. Letter-spacing mechanism; space-key actions.- The letter-spacing escapement 33 for the type-carriage 15 is connected by a link 146 and arm 145 to a rock-shaft 144 provided with arms 143 carrying a universal bar 142 which is arranged in the path of screws 141 on the action-levers 58. The space-bar 150, Fig. 11, operates the escapement by means of relaymechanism constructed as described above and comprising a bell-crank 158 connected by a link 156 to one of the space-bar arms 151, and a link 159 connected to the rock-arm 75 and formed with a slot 160 engaging a pin 161 on one of the arms 143.