Patent GB-668921-A (GB)
Title: Improvements in or relating to printing telegraph apparatus
Inventor: SALMON REGINALD DENNIS
IPC: H04L17/24
Filed: 1950-05-22
Abstract: 668,921. Printing - telegraph receivers. CREED & CO., Ltd. May 22, 1950, No. 12764/50. Class 40 (iii). [Also in Group XXIV] Printing-telegraph apparatus comprises a rotatable member driven by a friction clutch from a constantly rotating shaft, a stop member for defining a stop position for said rotatable member, first and second stop arms resiliently connected to said rotatable member, a clutch lever rotatable independently of said stop arms, a clutch spring tending both to engage said friction clutch and to maintain said clutch lever in advance of said stop arms, means for bringing said stop member into the path of said stop arms and said clutch lever, means for causing said clutch lever when arrested to oppose said clutch spring to disengage said friction clutch, means for causing said stop arms to be positioned on opposite sides of stop member and damping means for bringing said rotatable member to rest in a position defined by said stop member after a limited amount of oscillation about said position. The arrangement differs from that described in Specification 651,470 by the provision of the clutch lever which is actuated by the stop member to disengage the driving clutch a short time prior to the engagement of the first stop arm with the stop member. In the embodiment shown, a type-wheel mounted on a splined shaft 19 and driven from a constantly rotated gear-wheel 2 is arrested at a position defined by a stop member 41 selected by the positioning of a number of notched permutation discs 1 set in accordance with the elements of a received signal. The gear-wheel 2 is integral with a sleeve 14 which carries a clutch housing 38 enclosing a helically wound clutch band 42 having one end engaged by an end of a clutch spring 29 and the other end in engagement with an extension 26 of a driving arm 17 secured to the shaft 19 by a clamping bolt 18. The other end of the clutch spring is secured in a tubular member 34 to which is spline-fitted a stop arm 25 having a downwardly extending portion 47 engaging one side of a channel portion 21 secured by an adjusting screw to the extension 26 of the driving arm 17. The spring 29 normally tends to contract and thus to expand the band 42 into engagement with the clutch housing so that the splined shaft 19 is driven from the sleeve 14. The spring 29 also acts on an extension 48 of a clutch lever 28 so that the latter is urged forwardly of the stop arm 25 and the engagement of the lever 28 with the stop member causes the spring 29 to be urged in the opposite direction, i.e. expanded, so that the helical clutch band 42 is contracted and disengages the drive of the splined shaft. A second stop arm 23 spline-fitted to a tubular sleeve 36 has an extension 46 held in engagement with the opposite side of the channel member 17 and is provided with a spring- biased latch member 22 so that on the arrestment of the stop arm 25 by the stop member 41 the second stop arm 23 passes beyond the member 41. The arms 23, 25 are resiliently linked by a coil spring 32 with its ends connected to dogs on the sleeves 34, 36. The connection to the sleeve 36 is effected by a collar 30 carrying on one side a connecting tooth and on the other side ratchet teeth engaging corresponding teeth on a second collar 8 splined to the sleeve 36. The spring 32 may be tensioned by rotating the collar 30, and if a more accurate adjustment is required, the number of splines on the collar 8 is arranged to be slightly different from the number of ratchet teeth on the collars 8, 30 so that the collar 8 can be removed and replaced in a different angular position relative to the collar 30. The latch arm 23 may be replaced by a resilient member having an inclined spring blade which allows the member to pass the stop member, but prevents its return.