Patent GB-336591-A (GB)
Title: Device for locking the platen of typewriters
IPC: B41J29/68
Filed: 1929-07-15
Abstract: 336,591. Kohler, O. July 15, 1929. Margin stops; locking-devices. - An attach ment for locking the platen after a predetermined number of line-spacing movements comprises a revoluble ring or segment gearing through an intermediate pinion with a pinion connected to the platen shaft, the movements of the ring o segment being limited by stationary and adjust able stops, and the intermediate pinion being releasable to permit of return of the ring o segment. The attachment may be arranged when in locking position, to operate the carriage releasing lever and thereby prevent the carriage from receiving letter-spacing movement. In the device shown in Figs. 3 and 4, a block 1, secured to the carriage and arranged eccentrically to the platen, is provided with a flanged cover 19, a spindle 10 passing through the block and cove being provided with a knob 9, and a square end entering the platen shaft 50. A toothed segmen 46 mounted in a flange 14 on the block is geared through an intermediate pinion 12 to a pinion 11 on the spindle. The intermediate pinion turns on a shaft 112 provided with eccentric pivots which can be rocked by means of a finger-lever to release the intermediate pinion The finger-lever engages locking-means on the cover. The movements of the segment are limited by a stationary stop 6 and an adjustable stop 7 carried by a revoluble ring 40 which is secured by a nut 43. After the predetermined number of line-spacing movements, the segment engages the stops 7 and the platen is arrested. On release of the intermediate pinion, the segment is returned by means of an arm 45 connected to a spring 16 which is tensioned by forward movement of the segment. The segment may be replaced by a ring, and the arm 45 and spring 16 may be replaced by a spring drum. The ring .has a mark which in the initial position is visible through a hole in the casing. To permit of return of the ring by turning the knob 9, the spring arrangements may be replaced by a pinion which engages the intermediate pinion when replaced from the ring. In the attachment shown in Figs. 13 and 14, a ring 4 revoluble in the block 1 gears through an intermediate pinion 12 with a pinion 11 on the spindle 10, the movements of the ring being limited by contact of a pin 5 thereon with a stationary stop, and an adjustable stop 33 secured to a ring 32 revoluble on a cap 27. The ring 32 has line-space graduations, and after being set with reference to a mark is secured by means of a pawl 7<1> which engages a stationary toothed ring 31. The pin 5 approaches the stop 33 at each line-spacing movement, and after the predetermined number of movements the pin engages the stop and the ring 4 and the platen are arrested. The ring 4 has graduations indicating the number of linespacing movements that have been performed. The pinion 12 has eccentric pivots 22 connected by means of a plate 26 and link 30 to a fingerlever 24. Depression of the finger-lever releases the pinion 12 from the ring 4 and permits a coiled spring 16 to return the ring. The spring is connected to a pinion engaging the ring, and one end engages the finger-lever and normally holds the pinion 12 in engagement with the pinion 11. The finger-lever is held in depressed position by a spring 38. The spindle 10 is provided with a knob 9, and an adjustable chuck 21 for engaging the platen shaft 20. Carriage-releasing arrangements. - For automatically releasing the carriage when the platen is locked by the attachment shown in Figs. 13 and 14, the carriage-releasing lever is arranged in engagement with a pin on the block 1. When the platen is locked, the block turns the releasing-lever and the carriage is released, and letterspacing movement being thereby prevented. The carriage remains released until the finger-lever 24 is depressed.