Patent GB-632717-A (GB)
Title: Improvement in typewriting machine
IPC: B41J25/18
Filed: 1947-06-05
Abstract: 632,717. Typewriters &c. UNDERWOOD CORPORATION. June 5, 1947, No. 14902. Convention date, May 31, 1939. [Class 100 (iv)] Column and tabular arrangements; tabulating key actions.-In a tabulator mechanism for a typewriter of the kind having a settable tabulator-stop on a fixed part of the typewriter, power means adapted to be rendered effective transitorily to set the stop and a type key lock, depression of a tabulator key causes the power means to set the tabulator stop and render the type-key-lock effective, latch means being provided to hold the tabulator stop in its set position and the type-key-lock effective independently of the power means. The required stop, of a series of stops 37 at letter-spacing intervals on the carriage may be depressed for engagement with the tabulator stop 45 by an arm 72 operated by a key 40 through linkage 61, 62, 63, 64, 67, 52, 68, the member 52 of which is restored by a spring 57. The arm 72 has a limited pivotal movement against a spring 77 so that should the arm enter into a space between the stops 37 when the key 40 is depressed it may yield as the carriage moves in a letter-spacing direction without creating sufficient friction to prevent restoration of the arm by the power of spring 57. The stops 37 are cleared by the operation of a key 41 which through linkage 142-147 raises a blade 51 so that as the carriage is moved in carriage return direction a cam 148 on the blade engages and restores the projected stops 37. When the tabulator bar 38 is depressed, a lever 80 engages a lever 84 having a pin-and-slot connection 90, 91 with a catch-member 88 which moves an actuator 97 downwardly to cause a pawl 106 thereon momentarily to engage the power-shaft 14. A forward movement is thereon imparted to the actuator 97, which is pivoted at its front end to a swinging lever 105 and suspended at the other end by a spring 111. Actuator 97 has a lost-motion connection 100 with an arm 98 rotating a lever 102 fast on a spindle 44 having a further lever 115 which by means of a link 116 rotates a lever 117 and thus moves the tabulator stop 45 into operative position. Stop 45 is latched in the operative position by a block 126 thereon engaging, under the action of a sideways-pulling spring, with a part on the fixed frame 13, but the actuator 97 is permitted by the lost-motion connection 100 to return under the action of the spring 111 to its normal position. A lug 96 on 'the actuator engages a cam surface of the catch 88 to restore it against an ear 93 on the lever 84. Simultaneously with the setting of the stop 45 an escapement mechanism 32-34 is released by the lever 117 which through a bellcrank 121, 122 disengages a dog-rocker 33 to permit free travel of the carriage under the pull of spring-drum 132. The stop 45 is restored and the escapement re-engaged by the action of a spring 46 on the stop 45 when a projected stop 37 strikes the stop 45 which is moved sidewardly and thereby releases the latch 126. Key interlocks.-The depression of the tabulator bar 38 prevents operation of any other keys by means of an end part 134 of the lever 84 which enters between a series of discs arranged as a continuous series in. a race in a key-lock bar having only the space for the thickness of one key in the entire line of discs. The lever 84 is maintained in this position whilst the stop 45 is operative, by the engagement therewith of a pin 133 on the lever 102.