GB433921A - Improvements in and relating to shock-absorbing mechanism for typewriting machines - Google Patents

Abstract

433,921. Typewriters. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.- (Underwood Elliott Fisher Co.; 342, Madison Avenue, New York, U.S.A.) Jan. 18, 1935, No. 1784. [Class 100 (iv)] Carriage - retarding devices.-In arrangements for arresting the carriage at the end of the return movement comprising shockabsorbing mechanism for gradually resisting movement beyond the marginal position, and shock-absorbing mechanism for resisting movement back to the marginal position, the same mechanism is employed for resisting both movements. 'In the arrangement shown in Fig. 1, a type-carriage 1 running on rails 3 is drawn towards the right-hand for letterspacing by means of a spring drum and is controlled by means of an escapement wheel which is mounted on the type-carriage and is geared to rack 5, a margin stop 4 for limiting return movement of the type-carriage being adjustably mounted on the rack. The rack is now mounted to move longitudinally on blocks 18 on the frame 3, and is associated with a dashpot 23, Fig. 3, comprising a piston 30 mounted in a cylinder 29 formed with ports 40, 33. The port 33 is closed by means of a disc 34 carried by an adjustable spring 35. The port 40 is so disposed that the part a of the cylinder is of greater volume than the part b. The piston-rod 31 is connected to a lever 20 engaging a pin 28 on the rack, the pin being adjustable by means of a nut 25 co-operating with a threaded rod 27 carrying the pin. Normally the rack abuts on an adjustable stop 60, and the piston is at the right of the port 40. When the type-carriage is returned, an abutment 6 thereon engages the margin stop, the rack is moved to the left, the piston moves past the port 40, and the rack and type-carriage are gradually arrested in over-margin position by the gradually increasing back-pressure of the air in the part a of the cylinder. The compressed air and the spring drum are then effective to return the rack and type-carriage quickly to normal position, as determined by the stop 60, the final part of the movement being abruptly cushioned by compression of air in the part b of the cylinder. The dashpot 23 may be replaced by a liquid dashpot consisting of a cylinder, and a piston resting on a spring and formed with a small throughport. Specification 411,278 is referred to.