Patent GB-210894-A (GB)
Title: Improvements in typewriting machines
IPC: B41J23/06
Filed: 1922-11-14
Abstract: 210,894. Brougham, F J., (Addograph Co.). Nov. 14, 1922. Relay type-lever actions. - Relates to typewriters having a power-driven universal typelever actuator operating the type-levers through selective mechanism, and particularly to typewriters of the kind described in Specification 25038/13, in which the actuator, on release from a latch due to the depression of a key-lever, is projected forward by a spring to operate the corresponding type-lever through a push-coupler raised into the path of the actuator by the key-lever and is withdrawn to the latched position by temporary pawl-and-ratchet connection with a shaft driven continuously by an electric or other motor. (1) The actuator 36, Fig. 2, is connected by a link 46 to a crank 47, Fig. 10, on a rotatable shaft 48 co-axial with, but journaled independently of, the continuously driven power shaft 50. An arm 49 on the shaft 48 is normally held by a pivoted latch 34, and is released when the latch 34 is moved rearwaardly by a curved universal release-bar 29. On release of the latch, a spring 44 operates the actuator 36 and so the type-lever 15 through a push-coupler 18 raised into the path of the actuator by a vertical selectorrod 22 pivoted to the key-lever 23. A pawl 55 on the arm 49 is normally held out of engagement with a ratchet wheel 53 on the shaft 50 by a stationary cam 54, but at the end of the forward movement of the actuator 36 the pawl leaves the cam and engages the ratchet wheel, the actuator being retracted to its latched position. The release-bar 29 is operated on the depression of any key-lever by a cam surface 28 on the push-coupler 18. The movement of the actuator 36 is reversed by the shaft 50 before the type-lever 15 reaches the platen and when the type is at a distance from the platen which is the same for all the typelevers, the type-lever completing its movement solely by its own momentum. (2) In the event of more than one type-lever being accidently operated, the machine is rendered inoperative. The strength of the spring 44 operating the actuator 36 may be sufficient to operate one, and not more than one, type-lever against its return spring 20. When more than one key-lever is operated, the corresponding type-levers then move part of the way only towards the platen and the actuator 36 stops above the push-couplers 18 of the remaining key-levers and prevents further operation of the machine until the operated type-levers are swung by hand to the platen and so returned to their normal positions. (3) In order to vary the depth of the impression, the tension of the spring 44 is adjustable without varying the length of-the stroke of the actuator 36. The spring 44, Figs. 2 and 4, is arranged in two reversed spirals around a sleeve 42 secured to a shaft 40, and the centre loop is held by a pin 43 on the shaft 40, the tension of the spring being varied by rotation of the shaft 40 through self-looking worm gearing 60, 61, Fig. 5, from a knob 63 on a shaft 62. Overwinding of the spring is prevented by a spring clip 64, engaging over a group of teeth on the gear wheel 60 and marked to indicate the tension of the spring. (4) The fore-and-aft position of the actuator 36 relatively to the type-lever 15 is made adjustable without altering the length of the actuator stroke by attaching the link 46 operating the actuator to a resilient arm 62<1> attached at its upper end to the actuator frame and bent relatively thereto by a set-screw with lock-nut. (5) In order to prevent noise and vibration, the stop 66,. Fig. 9, on the latch 34 engaging the arm 49 of the actuator mechanism is pivoted to the latch and supported by a spring 65. (6) Each push-coupler 18 is of sheet metal and the pivot of the typelever is supported between the body of the coupler and an integral parallel plate connected to the coupler bv two bridges 68 to one of which the return spring 20 of the type-lever is connected. (7) The release-bar 29 is given a bodily horizontal movement which is the same for all type-levers by supporting it on pivotal arms 30 in addition to the support formed by the latch 34. (8) Means causing repeated actuation of certain type-levers when the corresponding key-levers are held depressed comprise a tail lug 86, Fig. 16, on the push-coupler 18 resting and sliding on the top of the selector-rod 22, the surface 28 of the coupler 18 operating the release-bar 29 on each return of the type-lever to rest. The remaining type-levers are actuated once only at each key depression irrespective of the period of depression, the corresponding couplers having no lug 86, as shown in Fig. 2. (9) The rest 19, Figs. 2 and 16, for the push-couplers 18 is provided with upstanding guide fingers 27 for the couplers. The guide slots in the guide comb 21 for the selector-rods 22 are closed by a curved bar 70 connected to the comb. (10) Rebound of the type-levers 15 from their rest 75 is prevented, and the couplers are held all in the same position relatively to the actuator by an undercut or other shoulder 18<1> on each coupler 18 engaging a corresponding shoulder 59 on the coupler rest when the coupler drops back at the end of the forward stroke of the actuator 36. On depression of a key, the coupler is released from the shoulder 59 before the actuator 36 is released. (11) A series of springs 73 are arranged on the rest 75 to engage a heel lug or other part of the type-lever just before it strikes the platen and after it leaves the actuator, so as to accelerate the initial return movement of the type-lever, the springs 73 being preferably a curved series of leaf springs attached to the rest 75 by plates 76. Keys.-The touch on all the key-levers is varied simultaneously by vertical adjustment of a bar 78, Fig. 2, to which all the return springs 25 of the selector-rods 22 are attached. The bar 78 carries two laterally-resilient arms 79 pivoted to the frame at 80 and carrying serrations 82 with which a fixed projection 83 on the cover for the pivots of the key-levers may be adjustably engaged.