Patent GB-431910-A (GB)
Title: Improvements in carriage escapement mechanism for typewriting machines
IPC: B41J19/46
Filed: 1934-12-22
Abstract: 431,910. Typewriters. SMITH & CORONA TYPEWRITERS, Inc., L. C., Syracuse, New York, U.S.A. Dec. 22, 1934, No. 36880. Convention date, March 20. [Class 100 (iv)] Letter-spacing mechanism.-In escapements comprising a rocker provided with two dogs cooperating with an escapement-wheel, shock and noise are reduced by so supporting the rockeraxis that it can tilt in opposition to a yielding resistance when the escapement-wheel engages the dogs. Noise and shock may be further reduced by arranging the dogs to yield relatively to the rocker. In the escapement shown in Figs. 1, 2 and 5, a rocker 17 is provided with holding and stepping dogs 42, 41 co-operating with an escapement-wheel 15 geared to the carriage 10. The rocker is mounted in trunnions 20 in a yoke 18 which can rock on a pivot 21 on the framework 14 and is held in normal position by a stiff spring 23 abutting on a pin on the yoke. To permit adjustment of the spring, the pin is carried by an adjustable pivoted arm. Stops 39, 40 limit movement of the yoke. The rocker is connected to a universal bail 16 operated by the type-levers, and is normally held, by means of a spring 32, in contact with a stop formed by the head of a bolt 30 which is secured to the framework, and passes through an enlarged opening 31 in the rocker. Adjusting-means for the spring 32 comprises a screw 36 on an arm 35 connected to a revoluble cup 34 which engages one end of the spring. The holding- dog 42 is pivoted on a pin 76 on the rocker, and is held in normal position by strong opposed springs 77 which abut on the rocker and adjusting-screws 78. The stepping-dog 41 is pivoted by means of a pin 43 in the upper end of a plunger 54 which is mounted in the rocker and is pressed upwards by a spring 58. A stud 56 engages a movement-limiting slot in the plunger. Normally, the stepping-dog engages the escapement-wheel and abuts on a plunger 44 having a collar 45 abutting on a spring 48. To adjust the position of the stepping-dog, the plunger is adjusted by means of a nut 50 abutting on a rubber washer 52. The spring is adjusted by means of a nut 47. The stepping-dog, when released from the escapement-wheel, is rocked and then held yieldingly in displaced position by means of a plunger 73 which is mounted in the plunger 54 and is pressed upwards by a spring 75, a fork on the plunger 73 co-operating with the top of a slot 72 in the stepping-dog. On depression of the keys, the stepping-dog moves out of engagement with the escapement-wheel and is rocked by means of the plunger 73, and the carriage after making part of a letter-spacing movement is arrested by engagement of the escapementwheel with the holding-dog, the yoke 18 and the holding-dog yielding slightly to absorb shock. On release of the keys, the holding-dog moves out of engagement, the stepping-dog is rocked by the escapement-wheel into contact with the plunger 44, and the carriage completes a letterspacing movement, the plunger and yoke yielding slightly to absorb shock. When the carriage is returned, the stepping-dog is rocked and restored by the escapement-wheel and the plunger 73 respectively. Carriage releasing-arrangements.-Release is effected by depressing the plunger 54 and thereby releasing the stepping-dog 41 from the escapement-wheel 15. For this purpose, a release-lever 59 on the carriage 10 is arranged to operate a longitudinally and laterally movable bar 64 abutting on a roller 67 on a yoke 68 which abuts on a projection 54a on the plunger.