Patent GB-254169-A (GB)
Title: Improvements in line-spacing mechanism for typewriting machines
IPC: B41J19/84
Filed: 1925-11-13
Abstract: 254,169. Fairweather, W. C., [Underwood Typewriter Co.). Nov. 13, 1925. Line-spacing mechanism; platen-roller couplings.-The mechanism comprises a micrometer device for finely adjusting the unitary line-space, and a stop-device for determining the number of units, or preferably half-units, traversed at each operation; transmission mechanism for the linespacing lever may comprise a worm coupled thereto and engaging a rack or sector on the platen. As applied to a roller platen, the linespacing lever 51 is connected by a link 57 to a sector 41 engaging a loose pinion 40 on the spindle 26 of a worm 27 which engages a wormwheel 49a on the platen spindle 11. The pinion drives the worm by means of a one-way clutch consisting of members 29, 32 having fine-toothed rims, the member 29 being secured to the worm and the member 32 being loose and provided with inclines 36 engaging pins 39 on a disc 38 secured to the pinion. The member 32 is normally disengaged by a spring 34 arranged in a. cavity in the member 29 and surrounding a sleeve 33 on the member 32. On rocking the line-spacing lever, the pinion is rotated, the pins depress the member 32 into engagement with the member 29, and thereafter the pins drive the member 32 and cause the worm to rotate the platen. The member 32 is prevented from rotating before it engages the member 29 by means of a brake-shoe 44 carried by a light spring 45 and engaging the knurled periphery of the member; the spring 34 also aids in retarding the member. The driving- stroke of the line-spacing lever is limited by engagement of a stop 45 on the sector with the face of the pinion. Overthrow is prevented by a block 49 on the sector entering a recess 37 in the member 32, the block preventing the member from rising by filling the space between the bottom of the recess and the top 17 of a bracket 16. On releasing the line-spacing lever it is returned by a. spring and the member 32 is disengaged. The platen is normally free and can be turned by the knob 50, or for fine adjustment by a knob 26<a> on the worm spindle. The unit line-spacing movement is finely adjusted by means of a micrometer device consisting of a revoluble graduated disc 61, Fig. 1, mounted on the pivot 53 of the line-spacing lever-and having a spiral groove 57<a> engaging a pin 58 which connects the link 57 to a block 56 arranged to slide in a slot 55 in the line-spacing lever. The disc is retained in adjusted position by a spring. Line-spacing is varied, preferably in half-units, by means of an adjustable stop-pin 67 for determining the initial position of the line-spacing lever. The stop-pin is carried by a lever 65 having a pin 68 for engaging notches in a member 69 which can be rocked by a finger-piece 72. The worm and associated devices including the pinion 141 are mounted as a unit on a bracket 16 having top and bottom pieces 17, 18 joined by a yoke 19. As applied to platen-shift machines, the top 17 is secured by screws 20 to the platen frame 12, and the bottom 18 has an ear 21 secured by a screw 22 to a stud 23 on the front of one of the rock arms 13 supporting the platen frame in the carriage 15. The yoke 19 has a bearing for the platen spindle. The pivot 53 of the line-spacing lever is mounted in a lug on the carriage, and the link 57 engages a long pin 64 on the sector 41, the link moving over the pin when the platen is shifted. The line-spacing lever, micrometer device 61, and link 57 are assembled as a unit. The stop-device 67 - - 72 is assembled as a unit on a plate 66 secured to the carriage. To prevent straining of the platen frame by the line-spacing mechanism, the platen frame has a tie-rod 82 abutting on a bracket 81 on the carriage.