GB674812A - Rebound dampening devices for printing hammers - Google Patents

Abstract

674,812. Typewriters &c. NATIONAL CASH REGISTER CO. Nov. 13, 1950 [Nov. 18, 1949], No. 27637/50. Class 100 (iv). Hammer impression arrangements.-A rebound dampening device for a printing hammer comprises a freely mounted member 30 co-axially pivoted with the hammer 13 so as to move with the hammer during the printing stroke and to damp the hammer movements on the rebound. The member 30 carries one or more removable weights 33 and is formed with two flanges 31, 32 bent at right-angles so as to embrace the edges of the hammer 13 but spaced so as to permit of relative movement between the hammer and the member 30. In operation a cam 28, through leverage and linkage 24-27, pivots anti-clockwise an operating lever 19 and the hammer 13 pivots likewise by the pull of a spring 16 on the arm 15 of the hammer 13 carrying a pin 20 which follows the end 19a of the lever 19. When the cam 28 passes its highest point a sudden clockwise movement is given to the lever 19 by a spring 21 and the end 19a operates the hammer 13. The plate 30 travels therewith, and after impact between the hammer and the type 10, continues to move forwardly and as the hammer rebounds it engages the flange 32 and its movement is damped by the weight of the member 30 so that a second impression due to retensioning of the spring 21 by excessive rebound is prevented. The member 30 is biassed by gravity into the position shown and the flanges 31, 32 are lined with shock and noise absorbing material 34. The operating lever 19 has a block 18 normally in cushioned contact with a stop 22 secured to a machine frame.