GB1238149A - - Google Patents

Abstract

1,238,149. Typewriters. INTERNATIONAL BUSINESS MACHINES CORP. 12 June, 1970 [30 June, 1969], No. 28505/70. Heading B6F. Case-shift mechanism.-Instead of only moving the case-shift pulley 62, as in Specification 873,920, in the present Specification the typeselecting pulley 51 is simultaneously moved to counter partly the effect of the case-shift pulley 62. When pulley 62 has completed its movement, the type-selecting pulley 51 is returned to its original home position, so that the 180 degrees shift of the type head 55 is completed. Key lock and action of case-shift key.-Depression of shift key 111 moves a pivoted bellcrank 102 downwardly to flex a leaf spring latch 104. A horizontal arm 105 of bell-crank 102 drives a pawl 113 against upstanding arm 114 of interposer 110, to displace the interposer below a leaf spring latch 110a and trip cycle bail 34. The filter shaft 37 then drives interposer 110 to displace one bail 36 that is associated with a bail 46 of a selector mechanism 40. At the same time, interposer 110 pulls a control link 101 leftwards to set a shoulder 95 into alignment with an extension tab 65 of the caseshift pulley lever 61. Rotation of cam-shaft 43 now results in the movement of the case-shift pulley lever 61 via rod 93 and also the movement via bail 46 of the type selecting pulley lever 50. As filter shaft 37 completes its rotation, the interposer 110 displaces pawl 113 counterclockwise and shift key lever 112 remains depressed. The case-shift pulley lever 61 is retained in the shift position by latch 80 until such time as the operator releases key button 111. Key lever 112 then rises due to its bias spring 118, to lift pawl 113 to a position free of arm 114, whereby spring 117 pulls pawl 113 into operative alignment with the upper surface of arm 114. Continued upward movement of the shift key lever pulls the end 107 of bell-crank 102 clear of leaf spring latch 104 so that the bell-crank 102 drives interposer 110 downwards to initiate another cycle. As the cam-shaft 43 rotates causing lever 50 to move clockwise, rod 93 is moved leftwards toward the point where shoulder 95 will engage tab 65 so that the latch 80 is released. The return motion of rod 93 to the right is accompanied by simultaneous movement of the case-shift pulley lever 61 to its home position. Specifications 1,187,507, 983,549, 976,473, 873,920, 855,127, and 842,327 are referred to.