GB751170A - Floating escapement mechanism - Google Patents

Abstract

751,170. Typewriters. INTERNATIONAL BUSINESS MACHINES CORPORATION. June 2, 1954 [June 4, 1953], No. 16302/54. Class 100 (4). Letter spacing mechanism comprises a pawl 4 engaging teeth 10 of a rack 3 which has a floating engagement with a carriage base 2 by means of pins 32 in slots 33. The pawl 4 and a plate 22 are mounted for pivoting and sliding on a pin 17 and are urged by springs 18, 25 to the right in Fig. 2, the nose 13 of the pawl 4 being also urged into engagement with the teeth 10. In the rest position, Fig. 2, the carriage base under the action of the usual spring tape forces the pawl to the left against the spring 18 and the pins 32 into contact with the left ends 38 of the slots 33. On actuation, the nose of a trip lever 5 contacts a shoulder 26 of the plate 22 which swings the pawl 4 out of contact with the teeth 10 until its tail 15 moves out of contact with the shoulder 26, Fig. 3, allowing the nose 13 of the pawl to run down the surface 14 of the teeth 10 as the rack 3 moves rapidly to the left, under the action of a spring 34 until the pins 32 contact the ends 37 of the slots 33. The thus released heavier carriage base 2 moves more slowly to the left until the nose 13 of the pawl contacts the surface 11 of the teeth 10 and restores the parts to the position shown in Fig. 2. This arrangement is said to reduce noise and to allow greater typing speeds.