Patent GB-224454-A (GB)
Title: Improvements in case shift mechanism for typewriters
IPC: B41J1/14
Filed: 1924-03-24
Abstract: 224,454. Hess, E. B., and Royal Typewriter Co., Inc. March 24, 1924. Platen, carriage, and case shift mechanism.- Relates to repulser mechanism for giving an initial impulse to the shifted member, such as the paper carriage, the platen, or the type-lever segment, on its return movement, and consists in means to ensure that the repulser mechanism is put into the operative position only when the shift is effected by a rapid depression of the. shift key. The carriage B is supported on a shift rail D provided with downwardly extending legs E pivotally connected to the machine frame A bv arms F at their upper ends f and by shift levers G at their lower ends g. The arms F and levers G are pivoted to the machine frame at f<1>, g<1> respectively. The repulser device comprises a spring S secured at its lower end to a bracket T on the frame and connected at its upper end to one arm r<1> of a two armed lever R pivoted at r to the front end of one of the shift levers G. Within the spring S is a small cylinder U of indiarubber, leather, or the like, with its lower end resting on an adjusting screw U<1>. When in the normal position, the arm r<1> of the lever R rests on the upper end of the cylinder U. The shift key K, pivoted at K<2>, has a vertical arm k connected by a link Q' to a bell-crank Q, which is pivoted on the shift !ever G at q. A link H<1> connects the arm k to a latch H for holding the carriage in the lower position. A lost-motion connection between the link Q<1> and the bell-crank Q permits the latch H to be withdrawn before the shift lever operates to shift the carriage. The stroke of the shift key is cushioned bv a spring Q<2> connected between the rear arm of the bell crank and a rear projection g<2> on the shift lever G. The movement of the bell crank is limited by providing its lower arm with side flanges q<3> between which extends a projection q<4> on the shift lever. Vertical counterbalancing springs 0, normally in tension, are arranged to the front and rear of the centre of gravity of the carriage, and are extended between a flanged plate O<1> on the machine frame and an adjustable member P attached to the leg E of the shift frame at g. Preferably two counterbalancing springs are provided at each end of the carriage. When the machine is operated slowly by a light touch on the shift key, the carriage is raised by the counterbalancing springs, and when released the carriage returns to its normal position solely by gravity. When the shift key is depressed rapidly, a sudden upward movement is given to the front end of the shift lever G, and the two-armed lever R, restrained at its front end r<1> by the repulser spring S, turns rapidly about its pivot r and puts the notch x into engagement with a latch W pivoted on the shift lever G at Q. The notch x and latch W remain in engagement during the upward movement of the carriage and cause the spring S to be placed under increasing tension as the carriage rises, thereby enabling the carriage to be returned quickly when released. Shift-lock mechanism of the usual construction can be operated by a shift-lock lever L<2>. Specification 213,068 is referred to.