Patent GB-537420-A (GB)
Title: Power transmitting apparatus
IPC: H04L13/04
Filed: 1939-09-19
Abstract: 537,420. Clutches. CREED & CO., Ltd. Sept. 19 1939, No. 26158. Convention date, Sept. 24, 1938. [Class 80 (ii)] Clutch mechanism comprises driving. and driven members positively engaged when operating and completely disengaged when idle, a shaft to be driven by the clutch being connected to the driven member through a spring which, upon arrest of the shaft, is further tensioned so that when the shaft is again released, the spring initiates rotation of the shaft while the clutch members are being engaged. Fig. 1, shows one form, with the parts of the clutch separated, suitable for driving the shaft 11 of the type wheel 42 of a printing telegraph, the shaft 11 being alternatively held and released by selectivity controlled pins and an arm 49 in known manner. The clutch comprises a toothed sleeve 14 secured to a gear 12 loose on the shaft 11 and continuously rotated in anti-clockwise direction by a motor-driven pinion 13, and a co-operating driven toothed sleeve 17 also loose on the shaft and slidably connected by slots 19 to lugs 21 on a bush 22 loose on the shaft. A coiled spring 27 has its ends connected to a lug 29 on the bush 22 and a lug 28 on a spring drum 24 fixed to the shaft 11 by a nut 26. A pin 32 fixed to the shaft 11 projects through an aperture 31 in the sleeve 17, the aperture having an inclined edge 33, and a compression spring 23 is arranged between the bush 22 and sleeve 17. A ratchet wheel 34 fixed to the sleeve 17 co-operates with a pawl 36 on a fixed but adjustable bracket 35 to prevent clockwise rotation of the sleeve 17. The pawl is adjusted by a screw 39 so as to be clear of the wheel 34 when the clutch members 14, 17 are engaged. The spring 27 is given an initial tension tending to turn the shaft 11 in an anti-clockwise direction. When the shaft 11 is released, this tension starts the rotation of the shaft so that the pin 32 leaves the edge 33 of the aperture 31 and allows the spring 23 to move the sleeve 17 into engagement with the sleeve 14. Further rotation of the shaft is then effected by the clutch acting through the spring 27. When the shaft is again arrested the sleeve 17 continues to rotate, winding up the spring 27, until the edge 33 by engaging the pin 32 opens the clutch and moves the ratchet wheel 34 into engagement with the pawl 36. Fig. 2 shows a modification in which a clutch member 66 in the form of a ratchet wheel is fixed to a sleeve 62 loose upon the shaft 61 of the type wheel 88 and driven continuously in clockwise direction by a pinion 63. The sleeve 62 passes freely through a ratchet wheel 71 secured to a fixed block 68. A coiled spring 76 has its inner and outer ends fixed respectively to lugs 74 and 77 on a plate 73 loose on the shaft 61 and on an arm 78 fixed to the shaft. A forked arm 87 also fixed to the shaft 61 embraces an arm 86 of a rockshaft 83 carried by the plate 73 and to which is fixed a pawl 84 co-operating with the clutch wheel 66, a spring 85 on the shaft 83 tending to hold the pawl 84 out of engagement with the wheel 66 and in contact with an arm 80 fixed to a pawl 81 so as to press this pawl into engagement with the fixed ratchet wheel 71. The pawl 81 is pivoted on a stud 79 carried by the plate 73. When the shaft 61 is released, it is turned initially in clockwise direction by the spring 76 until, by the engagement of one tine of the member 87 with the arm 86, the pawl 84 is engaged with the clutch wheel 66 after which the shaft is rotated by the clutch acting through the spring 76. When the shaft is arrested , the plate 73 continues its rotation by the pawl 84, winding up the spring 76, until the arm 86, by engagement with the other tine of the member 87, is turned to throw out the pawl 84. In two further modifications having a constantly driven ratchet clutch wheel and a fixed locking ratchet wheel, the pawls co-operating with these wheels are fixed to a common spindle carried by a plate such as 73 to which the coiled spring such as 76 is attached. In one of these modifications, the pawl spindle is actuated by a projection on the type wheel shaft engaging between the tines of a forked member pivoted to the plate and connected by a spring rod to an arm on the pawl spindle. In the other modification, the pawl spindle is actuated by a forked member such as 87 fixed to the type wheel shaft engaging an arm such as 86 on the spindle, the movements of the arm between the tines being actuated by a spring-pressed member engaging the arm.