GB991922A - Typing impression control for typewriters - Google Patents

Abstract

991,922. Typewriters. SPERRY RAND CORPORATION. July 4, 1961 [July 11, 1960], No. 24131/61. Heading B6F. Collective adjustment of impact.-The force of impact of all type levers 24 is determined by the length of time a cam 13 is in contact with a continuously rotating power roller 11, and by the effect of a camming roller 16 on a crank lever 17. This is controlled by cranks 15 carrying adjustable screws 65-66 which engage a movable limit strip 44 on a carrier bar 30, mounted for vertical movement on a lever 32 adjustable by a knob cam control 65-68 and linkage 70-72 thereby collectively varying the distance of movement of all the adjustable screws 65-56. Letter - by - letter adjustment.- Individual impact control for each letter is made by adjustment of screws 55, 56 in lugs 54 on base members 53 of the cranks 15. A nylon strip 57 with tight screw holes prevents the screws becoming loose. Which of the screws 55, 56 that engage the strip 44, is determined by the case-shift position. A crank 49, 47 is operated by a case-shift action (see below) and a bail rocker 46 is drawn upwardly from the position in Fig. 1 to that in Fig. 2 (not shown). This pulls the legs 36, 37 if a wire bail and slides the strip 44 from above one row of screws 55 to the other row 56. Case-shift action.-Operation of case shift key 97 operates linkage 96, 94, Fig. 3, and cranks 88, 89 pivot. A pawl 86 is released either by the nose 87 or 91 according to which case - shift position exists and the pawl engages a ratchet 81 keyed to a continuously rotating shaft 80. The pawl thereby rotates an eccentric disc 82 on which it is mounted a half-arevolution to raise or lower an arm 51 connected to the type-basket. It is this arm 51 which operates the crank 47 to alter the impression adjustment mechanism referred to above.