Patent GB-374736-A (GB)
Title: Improvements in devices for locking the platen of typewriters
IPC: B41J29/68
Filed: 1931-09-23
Abstract: 374,736. Typewriters. CLEVELAND, F. J., 29, Southampton Buildings, London.- (Heindl & Petters; 87, Josefstadterstrasse, Vienna.) Sept. 23, 1931, No. 26585. [Class 100 (iv).] Margin stops; locking-devices.-In a device for locking the platen after a predetermined number of.line-spaces comprising a curved rack geared by an intermediate pinion to the platen shaft, the stop arrangements for limiting movement of the curved rack comprise a stop formed thereon and adapted to engage directly the teeth of the intermediate wheel. The device shown in Fig. 2 comprises a casing 1 carrying internally-toothed rings 2, 5, a scale-drum 3, an intermediate pinion 20, and a shaft 11 provided with a splined pinion 16 connected to a knob 17. The ring 2 is formed with an internal stop for engaging directly the teeth of the intermediate pinion. The casing is secured to a bracket 10 on the carriage, and the shaft 11 is coupled to the platen shaft 13. The pinion 20 engages the ring 2 and is connected to a returning-spring 22. The scale-drum is secured to the ring 5 and is held in adjusted position by means of teeth 26 which are connected to a spring-urged knob 28 and co-operate with the ring 5. To adjust the device, the teeth 26 are released, and the scale-drum is set to indicate the maximum number of lines on the sheet, the ring being caused by means of co-operating stops 25, 7 to turn with the scale-drum. The teeth 26 are then permitted to re-engage the ring 5, and the pinion 16 is moved into engagement with the ring 2. At each operation of the line-spacing mechanism or the knob 17, the ring 2 is stepped forwards, and when the maximum number of lines has been typed, the internal stop on the ring co-operates with the pinion 20 to lock the platen. On retraction of the knob 17, the platen is unlocked and the pinion 20 returns the ring 2 to the initial position determined by the stops 7, 25. In the device shown in Fig. 4, the ring 2 is secured to the scale-drum 3, and during adjustment, the stop 25 on the ring 2 co-operates with the stop 7 on the ring 5 to turn the ring 5 and thereby set the stop 7. The drum and the ring 2 are then permitted to return to initial position, and the ring 5 is held by means of a tooth 43 on a laterally movable bracket 44 which is connected to a spring-urged knob 47. In the initial position a stop formed on the ring 2 engages the intermediate pinion 20. The pinion 16 is then moved into engagement with the pinion 20, and when the maximum number of lines has been typed the pin 25 engages the pin 7 and locks the platen. The bracket 44 is formed with a scale-pointer 46. The returning-spring 22 for the pinion 20 is connected to an adjusting- knob 53 which is secured by a nut 55. The pinion 16 is provided with a sleeve 15 which is secured to the knob 17 and has slots 50, 51 for engaging a cross-pin 51 on the shaft 11 when the pinion is in disengaged and engaged position respectively, a spring 48 maintaining engagement. The device may be secured to the carriage by means of a three-armed bracket 62. In the device shown in Fig. 6, the ring 5 is omitted and the ring 2 is secured to a scaledrum 3 having a stop-member 58 formed with stops 56, 57 arranged in different circumferential and lateral positions. The stops co-operate with a stop-pin 43 passing through the casing 1 and secured to a laterally movable yoke 59 which is urged towards the right by a spring 45. A sliding abutment 61 holds the yoke in position for permitting co-operation of the stop-pin and the stop 56 to lock the platen when sheets of a certain standard size are employed, whilst on depression of the abutment the stop-pin can co-operate with the stop 57 to lock the platen when sheets of a larger standard size are employed. When sheets of another size are employed, the scale-drum is set initially in correspondence with the size, and the platen is locked by co-operation of the stop-pin and the stop 57.