GB501717A - Improvements in or relating to telegraph apparatus - Google Patents

Abstract

501,717. Type - printing telegraphy. CREED & CO., Ltd., THOMPSON, A. E., and SALMON, R. D. Aug. 27,1937, No. 22843/38. Divided out of 490,361. [Class 40 (iii)] A step-by-step' telegraph receiver has a printing-hammer actuated by a cam mounted on a shaft, a detent, holding said shaft, being released to allow rotation thereof at the termination of a series of received impulses. A detent cam 37, Fig. 1 (Prov.), mounted on the shaft 35 which carries the printing cam, is held against rotation by a detent 49 on a lever 38 pivoted on a stud.39. This detent 49 is held in position by the lower projection of a frame 41 mounted on a pivot 42, Fig. 2 (Prov.). Slidably mounted in the frame 41 is a rod 44 carried on a lever 45 also pivoted on the stud 39. This rod 44 is held down against the action of a spring 46 by an arm 47 pivoted on a shaft 51 which is controlled, by means described later, so that it moves in a clockwise. direction during the receipt of impulses and returns at the termination of a series of impulses. Thp initial clockwise movement allows the rod 44 and lever 45 to be raised slightly by the spring 46 until a projection at the further end of the lever 45 is held by the lever 38. When the lever 47 returns at the termination of a series of impulses its lower end strikes the rod 44 and the resultant movement tilts the frame 41 so removing its lower projection from the detent 49 and allowing the latter to be raised by a spring 40. Rotation of the printing shaft 35 is thus permitted for a quarter revolution, the detent 49 being reset by means of a roller 61, on the lever 38, operated by a resetting cam 62 on the shaft 35. The resetting movement of the lever 38 returns the lever 45 to its initial position, the rod 44,carried by it causing the frame 41 to return to the position in which it holds the detent 49. The arm 47 is connected so as to be operated by the armature of a magnet PM, Fig. 1 (Comp.), which is slow to operate but quick to release and whose armature is normally attracted with the arm 47 in the position of Fig. 1 (Prov.). The magnet PM is in parallel with a magnet EM which controls the escapement of the typewheel and the two are in series with a polarised line relay LR. On receipt of impulses the armature lr of the line relay LR is operated and the quick release magnet PM allows the arm 47 to rotate clockwise. At the termination of the impulses, the magnet PM, being slow to operate, has sufficient time to attract its armature and return the arm 47 to its initial position, so operating the printing mechanism as described. Specifications 490,361 and 490,413 are referred to.