Patent GB-807114-A (GB)
Title: Improvements in and relating to proportional spacing mechanism for typewriters
IPC: B41J19/32
Filed: 1956-10-26
Abstract: 807,114. Typewriters &c. ROYAL McBEE CORPORATION. Oct. 26, 1956 [Nov. 4, 1955], No. 32798/56. Class 100(4) A proportional escapement mechanism for controlling an escapement in typewriters, has a single feed pawl 166, Fig. 12, adapted to engage and disengage escapement 175, means 161 adapted to disengage pawl 166, means 180, not shown, which lock pawl 166 in disengaged position, and means 177 adapted to actuate locking means 180 to unlock pawl 166 to engage escapement 175. Type bars are operated by power roller and cam. Universal bar 4, Fig. 4, frees the escapement by lifting finger 167, Fig. 12, out of engagement through linkages 150, 152, 160, 154, 161, 171. Feed pawl 166, locked in disengaged position, is spring urged round the circumference of escapement wheel 175 re-engaging wheel 175. when arrested by an appropriate stop. Keys for letters requiring spacing other than normal have selectors 70, Fig 4, which set appropriate spacing stops in the path of pawl 166 through linkages such as 220, 213, 222, 235, 232, 229, 238, 286, 253. Framework. The escapement mechanism is housed in bracket 100, Fig. 10. Case-shift mechanism. Type levers are power urged into upper case position by segment 30, Fig. 28, through linkages 134, 136, 39, 86, 84, and 98 which is pulled by a cam engaging power roller 47 when the appropriate key is pressed. Segment 30 is power urged back to lower case position, cam release housing 123, not shown, initiating the movement through the above linkages. Plate 201, Fig. 2, is moved by linkages 132, Figs. 2, 28, and 206, so that projections 220, Fig. 4, are correctly aligned with selectors 70 for capital letter spacing. Justification. Expander key 300 Fig. 4, gives additional space to the character typed by varying the position of the escapement pawl stops which are all carried on expander arm 242, Fig. 19, through linkages 304, 303, 240. Back-spacing mechanism. Escapement wheel 175 is turned back one tooth by pawl 353, Fig. 20, moved by lever 350, slide 340 and a clevis rod, when cam 48, Fig. 4, is pushed into contact with power roller 47 by the back spacing key. During carriage return and tabulation back spacing is impossible as lever 310 disengages slider 340 from lever 350. Tabulation. A tabulator stop 43, not shown, is set in the path of lug 417, Fig. 21, and contact end 551. On pressing the tabulator key the escapement is released by lever 310 which lifts the feed pawl out of engagement. Lever 310 is lifted by power through 371, 372, 377, 375, 401, 397, 407, Fig. 21, and 405, 406, 311, Fig. 22, and held in pawl disengaging position by tabulator safety dog 325, not shown. Simultaneously, lug 417 is moved into stop arresting position by 372, 413, 411, 416 and held by latch 426. Latch 562 moves to place projection 563 behind lever 550. Stop 43 moves bar 416 to the right on impact, allowing it to drop alongside latch 426. Contact end 551 is also pushed to the right and releases feed pawl 167 to engage escapement 175 through linkages 552, 325. Lever 550 drops back to its original position as in Fig. 21. Decimal tabulation is possible but not described. Carriage-returning machanism. Depressing the carriage return key actuates a cam 48, Fig. 4, which causes the clutch to engage the carriage with the eletric motor and moves projection 633, Fig. 21, through linkages 606, 375, 388, 377, 372, 400, 617, 616, 632, out of the path of marginal stop 603A which strikes projection 418 and rebounds. The escapement feed pawl is disengaged through 375, 401, 397, 407, 405, 406, 311, 310. The carriage travels until stop guide 604 strikes projection 624 locking escapement feed pawl in disengaged position through 623, 610, 611. In pivoting, lever 610 disengages the clutch through 375, 606. Whilst the carriage is rebounding projection 633 is moved between 603A and 418 by 375, 400, 617, 616, 632. Disengaging the clutch allows the carriage to move in letter spacing direction its movement being arrested by the escapement pawl released by 624, 610, 611. A safety device ensures correct margin setting when the carriage is inadvertently hand returned. The tabulator and carriage return keys are interconnected. Carriage return over-rides tabulation in the event of the tabulation key being inadvertently pressed first. Specification 693,685 [Group XXXVIII] and U.S.A. Specifications 1,600,252, 2,111,410, 2,385,035, 2,517,989 and 2,547,449 are referred to.