GB806053A - Improvements in typewriters and escapement mechanisms therefor - Google Patents

Abstract

806,053. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 18, 1955 [Nov. 19, 1954], No. 33073/55. Class 100(4) In a typewriter having a proportional escapement mechanism as described in Specification 673,685 means are provided to lift the pawls during a power operated carriage return and to re-engage them just before the carriage overruns the margin stops. Operation of a bell crank 2, Fig. 1, to start the carriage return pulls on the lever 8 which through a latch 10, an arm 12, and link 14 actuates a bell crank 16, Fig. 3, which by a stud 20 actuates a release lever 22 to withdraw the escapement pawls 26 from the rack. At the same time the stud 20 rotates an intermediate gripping lever 31 which acts through the finger 39 of lever 35 engaging the edges 41 to group the pawls and a catch 34 then holds the catch part 32 of the lever 31. As the carriage approaches the margin an adjustable stop 60 engages a lever 64 an ear 70 of which acts on a finger 72 of a control lever 74 which by a bell crank 80 operates an air cylinder 88 to cushion the return and by an intermediate unlatching lever 90 disengages gears 62, 58 of the latch 10 so that the link 14 is freed and allows the pawls to re-engage the rack. The pawls however remain grouped until the shortest pawl of one of the groups engages a rack tooth causing its gear 42, Fig. 3, to engage the lip 46 of an unlatching lever 38 which withdraws the latch 34 permitting the pawls to become ungrouped. Means are provided to group the pawls during manual carriage return. Tabulating. In tabulating check lever 100, Fig. 1, acts to operate the bell crank 16 the pawls being similarly re-engaged and then ungrouped by the action of a tab stop. Means are provided to prevent or stop carriage return when tabulation is occurring. U.S.A. Specifications 1,935,436 and 1,955,614 aLso are referred to.