Patent GB-688053-A (GB)
Title: Key-controlled margin stop adjustment means for typewriting machines
IPC: B41J29/50
Filed: 1950-06-12
Abstract: 688,053. Typewriters &c. UNDERWOOD CORPORATION. June 12, 1950 [June 28, 1949], No. 14588/50. Class 100 (iv). Margin-stop adjusting-mechanism for a typewriter comprises a control mechanism, preferably included in or near the main keyboard, which unlocks the margin stops when they reach a limiting counterstop and permits their adjustment step-by-step.in a leftward or rightward direction by power or spring movements of the typewriter carriage. The carriage 15 is transversely movable on trackway 17, 18 and carries a platen 21, a tabulation-stop-carrying bar 78, and a margin-stop bar 47 and is geared by a rack 30 to a pinion 28 axially connected to an escapement mechanism 26, 29, 33, 34. The margin stop bar 47 carries two margin stops 44, 45, Fig. 3, each normally locked into a tooth 55 of the bar 47 by a spring lock slide 52 and each having a second vertically-moving slide 165 formed with an inwardly directed nose piece 271 which engages underneath an unlocking element 122 when either of the margin stops 44, 45 is moved by the carriage movement into the centre of the machine, and in which position a surface 70 on either of the stops encounters a counterstop 46. The movement of either margin stop into central position conditions the unlocking element 122 for operation by moving it forwards, thus releasing it from a protrusion 157 formed in a plate 62 of a central framework 63. Protrusion 157 normally engages within a slot 160 in the unlocking element 122 and is held there by a slotted slide 152 urged rearwardly by a spring. When a margin stop 44 or 45 arrives in central position, cam surfaces 161 or 164 engage cams 162 or 163 on the unlocking element 122 and move it clear of the protrusion 157. The slides 165 also prevent a downward releasing movement of the unlocking element 122 while they are positioned over the plate 62 until they are in exact central position where the foot portions may descend into recesses 176 or 177 to lock the margin stops to the framework 63. The operation of the unlocking element 122 is effected from a key 124 on the keyboard, Fig. 7, which operates linkage 125-128, Fig. 1, bellcrank 130, lever 135, Fig. 3, vertical element 138, and, through a yielding connection 150, 151, the lower section 144 of the unlocking element 122; the screws 145 adjustably join the section 144 with the element 122. The lefthand margin stop 44 is brought into central position by the operation of a carriage-return key 72 and power-operated carriage-return mechanism which is automatically disconnected by leftward movement of the counterstop 46 in a manner similar to that described in Specification 530,359 and the righthand margin stop 45 is brought to central position by the operation of a tabulator key 71 whereupon the carriage moves leftwardly by the pull of a spring coil 23, 24 in a manner described in Specification 632,717. If several tabulator stops 77 are in downward position to contact a tabulator counterstop 79, several depressions of the tabulator key 71 may be necessary to complete the movement of margin stop 45 into central position. If the margin stop 45 is positioned between two tabulator stops 77, the tabulator counterstop 79 is tripped by a pin 87, Fig. 1, attached to the rear of the counterstop 46 which is moved by the surface 70. With either of the margin stops free on the carriage bar 47 and fixed relatively to the framework 63 movement of the carriage will adjust the margin stop. Leftward movement of the carriage causes rightward repositioning of the stop thereon by means of a key 180 rocking a lever 182 pivoted at 183 so that a hook 185, adjustable by cam slot and spring 214, 212, 213 on the lever 182, engages a lug 179 on an actuator 186, 187 which is drawn downwardly into contact with a snatch roll 38. A link 191 connected to the rear of the actuator 186 transmits a letter-space releasing movement to the escapement mechanism through lever 192, shaft 195, lever 193, roller 194, and escapement rocker 33. If the key 180 is held depressed, the actuator is re-engaged by the roll 38 by reason of the lug 79 riding downwardly and rearwardly along the cam face 178 of the hook 185. Contact between actuator and roll 38 is assisted by spring lever 204. This actuator also effects normal letterspacing but is engaged by a differently-shaped hook 211 from a space key 210 which does not cause re-engagement of the actuator and roll if the key-lever is held depressed. The leftward positioning of a margin stop is effected by a. key 181, Figs. 2, 7, through a one-revolution clutch mechanism shown on Fig. 2, to backspace the escapement mechanism 237, 26, a slotted bearing 242 for the shaft 236 being provided to enable idle displacement of the shaft 236 whenever the escapement wheel 26 cannot turn due to the carriage having reached limit position. The adjusting operations in certain cases may be speeded up e.g. movement of lefthand margin stop 44 may be adjusted to the extreme lefthand position by operation of keys 124 and 72 simultaneously, the unlocking element 122 moving downwardly after contact between the stop 44 and counterstop 46 by the pull of the spring 151 forming the yielding connection from the key 124. To prevent damage by the depression of a carriage return key with the righthand margin stop locked to the frame 63 the margin stops are provided with screws 171. The screw 171 on stop 44 travelling with the carriage engages screw 171 on stop 45 which is moved out of locking engagement with frame 63 by the upward camming of the slide 165 by the bevelled edge of the slot 176. The unlocking element 122 is also moved upwardly by the head of the slide 165 making room for the stop 44 which is consequently locked to the frame, and carriage return is halted, by an abutment 273 on the left end of the carriage moving the counterstop 46 to disconnect the carriage-return mechanism. In a similar manner damage to the machine is avoided, and the locking of the machine against further action is effected, by the engagement of the two screws 171, should a stop 44 be locked to the framework if the tabulator key is operated. A margin release key 266 is provided which lowers the counterstop 46 on its pivot 65. A locking of the type-lever actuators against operation occurs when the carriage reaches a line-end position as described in Specification 635,919 but in order that step-by-step movement of the carriage may be effected to adjust the margin stop the lever 182 of the key 180 is formed with an extension 264, Fig. 1, which disconnects the locking of the actuators. The operating mechanism for the type-levers is similar to that disclosed in Specification 635,916.