Patent GB-213068-A (GB)
Title: Improvements in case-shift mechanism for typewriters
IPC: B41J11/14
Filed: 1923-02-07
Abstract: 213,068. Hess, E. B., and Royal Typewriter Co., Inc. Feb. 7, 1923. Platen carriage, and case shift-mechanisms. -The shifted member, such as the paper carriage, the platen, or the type-lever segment, is given an initial impulse on its return movement by means brought into action only near the end or at the end of the shifting movement. In the carriage construction shown in the Figure, the usual counterbalancing spring T is adapted to supply the initial impulse to the return movement of the carriage B by being tensioned after the shifting movement, and in addition a spring X linked to the carriage is tensioned towards the end of the shifting movement. The carriage B is supported on a shift rail D provided with downwardly extending legs E connected at their lower ends to pivoted links F, and connected near their upper ends with rocker arms H on a rock shaft h. One end of the counterbalancing member V pivoted upon the arm H at v, the other end of the spring being connected to a toothed plate U pivoted at u to the machine frame A and adjusted by means of a screw U'. The and adjusted by means of a screw U<1>. The member V is provided with a downward extension v<1> pivotally connected at m to a link M which is adjustably connected by a link L to an arm k extending upwardly from the shift-key k. The arm k is also connected by a link N to a latch O adapted to engage a bracket P on one of the legs E to hold the carriage in the lower position. A spring o<1> connected between a lateral extension o of the member V and the latch tends to hold the latter in engagement with the bracket P. The member V also has an extension v<3> extending upwardly and forwardly and carrying a pin v<4> located within an inclined slot h<1> in the rocker arm H. When the shift-key is depressed, a lost-motion connection at m between the link M and the member V enables the latch O to be withdrawn first, and the carriage then rises to its full extent against a stop W on the frame. The tension of the spring T is fully relaxed during the upward movement, but the pin v<4> maintains its initial position in the slot h'. Further depression of the shift-key then causes the pin v' to move downwardly and rearwardly in the slot h<1> causing the member V to turn on its pivot v, thus putting the spring T under tension. Shift lock mechanism R, S, Q can be operated in the usual manner to lock the carriage in upper position. The spring X extending downwardly from the shift mechanism is provided at its lower end with an elongated loop x enclosing an adjustable eccentric x<1> secured to the machine frame. The lower end of the loop x comes in contact with the eccentric during the last part of the upward movement of the carriage and the spring is put under tension to assist the return movement. In a modification the carriage shift rail is provided with a downwardly extending bracket carrying a roller which engages a horizontal lever towards the end of the carriage shift. The lever is pivoted to a rock-shaft at the rear of the machine and is tilted when engaged by the roller, thereby tensioning a spring which may extend downwardly from the lever or may be coiled around the rock shaft. Keys.-The action of putting the spring T under tension, as described above, also serves to cushion the shift-key K.