GB275506A - Improvements in back-spacing mechanism for typewriting machines - Google Patents

Abstract

275,506. Fairweather, W. C., (L'nderwood Typewriter Co.). March 8, 1927. Back spacing mechanism.-Relates to mechanism of the kind in which the back-spacing pawl moves laterally into engagement with the rack and then longitudinally with the rack, and consists in the provision of a single spring adapted to move the pawl into engagement with the rack on operation of the back-spacing key, and to return the mechanism to normal position on release of the back-spacing key. The Figure shows mechanism comprising a pawl 37 pivoted at 38 to an arm 39 rocking on a stationary pivot 40, a link 29 being pivoted at 35 to the pawl and being pivoted also to an arm 27 on the shaft 26 of the back-spacing key-lever 25. The mechanism is now provided with a single spring 32 connected to a bracket 34 and a lug 33 at the rear of the link 29, an arm 28 at the front of the link being pivoted at 30 to the arm 27. The spring is initially strained and urges forward the link, but owing to the relative, disposition of the pivots 30, 40 forward movement is normally prevented and the arm 39 is retained in contact with a stop 44. On depression of the back-spacing key 24, the pivot 30 is depressed and the spring immediately moves forward the link, the pawl being thereby moved into engagerrent with the rack 15. On arrest of the arm 39. the continued depression of the key depresses the link and the pawl is moved longitudinally with the rack. On release of the key, the spring returns the mechanism to normal position.