Patent GB-412494-A (GB)
Title: Improvements in shift mechanism for typewriters and like machines
IPC: B41J25/24
Filed: 1933-12-06
Abstract: 412,494. Typewriters &c. AKT.-GES. VORM. SEIDEL & NAUMANN, 19, Hamburgerstrasse, Dresden, Germany. Dec. 6, 1933, No. 34326. Convention date, Dec. 10, 1932. [Class 100 (iv).] Case-shift mechanism; shift-key actions.-A type-lever segment, or other member, is shifted by means of a rocking bail, connected to a toggle which is connected at the middle pivot to another toggle operated by the shift-key, the toggles being approximately at right-angles and co-operating with a common stop. During the shift and return movements of the segment, the toggles cause the speed to increase towards the middle of the path and thereafter to decrease to zero so that the segment is moved and arrested without shock. The toggle-links and other members may, as described below, be provided with pivots which are adjustable for wear and are easily manufactured from stampings. In the mechanism shown in Fig. 2, a bail 3, mounted on pivots 2 on the sides 1 of the framework, is connected by links 9 to the segment 11. Counterbalancing-springs 7 are connected to lugs 5 on the bail. An extension of the bail is connected to a toggle 15<a>, 15b which is pivoted at 16 on the framework and is connected at the middle pivot 17 to another toggle 18<a>, 18<b> which is pivoted at 19 on the framework and is at right-angles to the other toggle. The toggle-link 18<b> has an arm 18<c> engaging a fork in a bell-crank 24 which abuts on a pin 25 on the shift-key lever 30. A spring 28 normally holds the toggle-link 18<a> in engagement with a stop 31. On depression of the shift-key, the toggle 18<a>, 18<b> is broken, the toggle 15<a>, 15b is straightened, the toggle-link 15b engages the stop 31, and the segment is depressed, the speed increasing towards the middle and thereafter decreasing to zero, so that the segment is moved and arrested without shock. On release of the shift-key, the toggle 15<a>, 15b is broken, the toggle 18<a>, 18<b> is straightened, and the segment is depressed, and is arrested without shock when the toggle-link 18<a> engages the stop. The stop and co-operating lugs on the toggle-links may have cushion-faces. To provide for adjustment of the travel of the segment, without altering the initial position thereof, each of the pivots 8 connecting the links 9 to the bail 3 is carried by a slide 34 which is mounted in an arcuate slot 33 in the bail and is provided with a revoluble adjusting-stud 36 having a lug 35 which engages a groove 33<1> in the bottom of the slot. The slide is adjustably secured to the bail by means of screws 37 passing through slots in the slide. The pivots 16, 19 each consist of a screw d passing through one wall of a slotted block c which is secured to the framework and receives the toggle-link 15b or 18<b>, the screw having a pointed or spherical end engaging a recess in the togglelink. The pivot 20, consists of screws d, Fig. 5, passing through a yoke g which receives the two toggle-links 18<a>, 18<b>, the screws having spherical ends engaging recesses in the togglelinks, and one of the toggle-links having a rounded part x and a stud h1<SP>1> bearing on and engaging a hole in the other toggle-link respectively. A lug 32 on one of the togglelinks prevents play of the yoke. The pivots 8, 10, 14 and 17 are constructed in a similar manner to the pivot 20. In the pivot 17 for the three toggle-links 18<a>, 15<a>, 15b, the middle link has studs engaging holes in the other toggle-links. Key-locks.-The shift-lock key-lever 43 has a pin 39 engaging a slot in a locking-lever 42 which is pivoted on 41 to the framework and engages an adjustable stud 44 on the shift-key lever 30, the locking-lever being arranged between the stud and the pivot 27 of the keylevers. On depression of the shift-lock key, the segment is locked in shifted position by co-operation of the stud with a quadrantal notch 42<11> in the locking-lever. Release is effected by slight depression of the shift-key.