Patent GB-821440-A (GB)
Title: Means for the prevention of rebounding in apparatus and machines, notable for use intelecommunication systems
Inventor: JACOBSEN HANS FREDERICK
IPC: H01H67/06
Filed: 1956-04-12
Abstract: 821,440. Stopping shafts in predetermined positions. DET STORE NORDISKE TELEGRAF-SELSKAB. A.S. April 12, 1956 [April 15, 1955], No. 11173/56. Class 80 (2). [Also in Group XL (b)] The shock due to positively stopping in a predetermined position a rectilinearly or rotationally moving member, such as a rotating typewheel 34 of a teleprinter or the driven member of a machine driven intermittently through a clutch, is transmitted elastically through the stop to an inertia member, and the moments of inertia of the moving and inertia members are so related that the moving member is stopped without rebound whilst the inertia member makes a stroke away from the stop. The principle is illustrated in Fig. 1, wherein moving and inertia members 10, 12 of equal moment of inertia are freely and independently pivoted at 16. When, after release, the moving member 10 strikes a fixed stop 14, the impact is transmitted through the stop to the inertia member 12 which makes an equal stroke away from the stop whilst the moving member 10 remains against the stop without rebound. In Fig. 4, not shown, a spring opposes outward movement of the inertia member 12 and its return is braked by a one-way dashpot. In a teleprinter, Figs. 5-7, the type-wheel 34 is secured to a rotating shaft 36 driven through a friction coupling and carrying an arm 38 which is arrested in any selected one of a number of angular positions by selecting one of a number of stationary levers 56 for outward pivotal movement about a knife-edge 54 into the path of the shaft-arm 38, such selection being made by a code mechanism comprising a number of discs 62 (not shown in Fig. 7) which are turned by plungers 72 in selected combinations about the shaft axis from idle positions in which the stop-levers 56 are held inward, to operative positions in which the one selected stop-lever 56 is permitted to move outwards by spring load 60 into notches 74 in the selected combination of code-discs 62. The stop-levers 56 pass, with working clearance only, through slots 58 in a disc 42 mounted on fixed frame-bolts 40, and with considerable circumferential clearance through slots 80 in a rotatable inertia member 76, Fig. 5, 90, Fig. 7, against which is pressed axially by springs 84 a friction-ring 82 which presses the inertia member 76 against the fixed disc 42. When, during operation, a selected combination of code discs 62 is turned to permit a corresponding stop-lever 56 to move outwards to arrest the shaft arm 38, the impact of the arm 38 is transmitted through the stop-lever 56 and leading edge of its slot 80 to the inertia member 76, 90 which then makes a forward turn limited by a fixed stop 92 and braked by the frictionring 82. At impact the momentum of the typewheel shaft 36 carries it slightly forward within the limit of the operating clearance of the stationary slot 58, this being the actual printing position. Coincidentally with each printing operation the friction ring 82 is turned by a cam 104 which is rotated one revolution for each operation and acts on the inertia member 76, 90 as follows. During the first part of the rotation the cam 104 turns the friction ring 82 slowly backwards bringing with it the inertia member from a forward position to which it was taken after the preceding operation. During the actual forward impact stroke of the inertia member 76, 90, the friction-ring 82 is stationary, for braking, and after that stroke the friction-ring 82, and with it the inertia member 76, 90 are turned rapidly forwards ready for the next operation. In Fig. 11, not shown, the friction brake-ring is on a separate parallel shaft and acts on the inertia member through contacting radial arms. The inertia member is returned to starting position by springs, and before complete return is detained in printing position by a pawl released by a rotating cam only after the stop-levers have been re-set for another operation.