Patent GB-190713227-A (GB)
Title: Improvements in Typewriting Machines
Inventor: KIDDER WELLINGTON PARKER
Filed: 1907-06-07
Granted: 1908-03-26
Abstract: 13,227. Kidder, W. P., and Sponsel, C. W. June 7. Typewriters.-In escapement mechanism, the pinion gearing with the carriage rack is connected with the escapement shaft by members, such as a pawl and a ratchet-wheel, which are automatically thrown clear of one another when the carriage is returned, so that the machine is rendered noiseless; a means for back spacing is also provided. A machine of the 'silent' class is shown, Fig. 1 being a section, Figs. 3 and 4 a detail in plan, and Figs. 6 and 7 details in bottom plan. Sliding types 3 are advanced by toggle mechanism against a platen 10 carried by a frame 17 which may be traversed on a rail 18 by the usual carriage spring. The feed-rack 21, preferably hinged to the frame 17, gears with a pinion 22 mounted loosely on a shaft 23 carrying an escapement wheel 37. A ratchet-wheel 30 fast on the shaft 23 is engaged by a pawl 29 pivoted at 28 on a flange 27 formed on a sleeve 26 on the pinion 22. A friction washer 31 of raw hide or the like and a collar 32 are placed between the wheel 30 and the flange 27, and these parts are held together by a spring 36. The collar 32 is formed with a notch 38 engaged by a lug 34 on the pawl 29. Normally, the pawl 29 engages the ratchet-wheel 30, as shown in Fig. 3, and locks the pinion 22 to the shaft 23 which is rotated step by step under control of the escapement. When the carriage is moved back, the pinion 22 is rotated slightly and the collar 32 is momentarily prevented from rotating by the friction of the washer 31. The movement of the flange 27 trips the pawl 29 by engagement of the lug 34 and the notch 38, as shown in Fig. 4, a stop 74 for the pawl being provided. Subsequently, the collar 32 rotates with the pinion 22. The pawl rides free of the ratchet-wheel, and the carriage may be returned without the noise due to clicking. At whatever position the carriage is allowed to rest, during the return movement, the friction between the collar 32 and the washer 31 acts in the reverse direction and swings the pawl into engagement. The escapement wheel 37, secured to the shaft 23, is engaged alternately by a fixed dog 39 and a swinging dog 38, both being carried by an arm 40 mounted on a shaft 41, which is connected by links 42, 43, 44 to a universal shaft 45 operated by a universal bar. The swinging dog 39 normatly engages the escapement wheel 37 and is held by a cam-stop 51, pivoted at 50 to the arm 40 and restrained by a spring 52. 'When swung clear of the wheel 37, the dog 39 is moved by the cam 51 against a cushion 53. On re-engagement with the wheel 37, the dog 39 is arrested noiselessly and without concussion by the cam 51. The means for back-spacing consists of a pawl 54 pivoted on an arm 56 loosely mounted on the shaft 23. The arm 56 is rocked by a rod 61 connected through a bell-crank lever and an arm with a key-lever. The pawl 54 has a curve extension 58 which is pressed by a spring 60 against a stud 59, and serves to maintain the pawl out of contact with the escapement wheel. When the rod 61 is rocked, the extension 58 rides along the stud 59 and the pawl 54 engages the escapement wheel which is thereby rotated, and with it the feed-pinion 22. To permit reverse rotation of the escapement wheel, the cushion' 53 is carried by a swinging block 71<1> pivoted at 72 on the arm 40. A spring 72<1> arrests the normal movement of the dog 39 and permits the dog 39 to swing clear of the escapement wheel when the escapement wheel is rotated reversely.