Patent GB-1473724-A (GB)
Title: Power transmission apparatus
IPC: F16H37/00
Filed: 1974-07-25
Abstract: 1473724 Clutches; clutch control FUJI ELECTRIC CO Ltd 25 July 1974 [25 July 1973 3 April 1974 10 June 1974 (2)] 32992/74 Headings F2C and F2L A shaft 6 is rotated by a worm 1 engaging a worm-wheel 2, the worm 1 being power driven, or the shaft is rotated by a hand wheel 7 the worm-wheel 2 being rotatably mounted on the shaft 6 and having a disc 4 with apertures 44 mounted, fixed for rotation with shaft 6, adjacent it, a further disc 5 having conical indentations 52 being mounted adjacent disc 4, the hand wheel 7 having projections 71 which pass through apertures of disc 5 and into apertures of disc 4 which latter allow rotation of the hand wheel relative to the disc 4 against the action of springs 81, 82 (Fig. 4). In the embodiment of Fig. 1 springs 31 in apertures 23 of the wheel 2 act against plungers 32 which connect together disc 4 and wheel 2 for rotation in the condition shown and bias balls 33 into the recesses 52 of disc 5 so that rotation of worm 1 rotates shaft 6 via plungers 32 and disc 4, the wheel 7 and disc 5 also rotating in this embodiment. Movement of the hand wheel 7, other than that due to worm 1, causes rotation of disc 5 relative to disc 4 due to the size of the apertures in disc 4 engaged by the projections 71 and so causes the balls 33 to be cammed out of recesses 52 which pushes the plungers 32 down so that they no longer interconnect disc 4 and wheel 2, the shaft 6 now being rotatable by the wheel 7 independently of the rotation of wormwheel 2. The springs 81 and 82 ensure that the disc 4 moves to restore the power drive from worm 1 when the hand wheel 7 is released. In the embodiment of Fig. 12 the spring 31, plunger 32 and ball 33 arrangement of Fig. 1 is replaced by a pair of balls 3 in the apertures 44 of disc 4 and which engage either indentations 21 in worm wheel 2 for power drive or indentations 52 of disc 5 for manual drive from hand wheel 7. In this embodiment an overload release means is provided by having disc 5 axially movable against springs 102 so that on stoppage of shaft 6 the worm-wheel 2 can cam the balls 3 out of the recesses 21. A sensor 100 may detect the overload and switch off the power drive (from an electric motor). In the embodiment of Fig. 12 the hand wheel does not rotate when shaft 6 is power driven due to a connection comprising pairs of balls 30 in a disc 400 which engage indentations 72 of the wheel 7 or indentations 57 in a member 55 having the projections engaging the apertures of discs 4 and 5. The wheel 7 also has projections 71 engaging in enlarged apertures in disc 400 with springs 87 and 88 centring the projections in the apertures, this permitting the balls 30 to be positioned as illustrated so that the shaft 6 can be rotated by the worm and wheel 1, 2 without the rotation of the member 55 rotating the wheel 7 which is held frictionally by an 0-ring 14 sufficiently to permit the movement of balls 30 in and out of the indentations 57 as member 55 rotates. Movement of hand wheel 7 moves the projections 71 in the apertures of disc 400, cams the balls out of indentations 72 and into indentations 57 and so connects hand wheel 7 and member 55 together for rotation to cause the balls 3 to move into apertures 52 and disconnect the drive from worm-wheel 2. Another embodiment is also described in which the arrangement is similar to that of Fig. 12 without any means of preventing the rotation of wheel 7 during power drive of shaft 6 (Fig. 5, not shown) and a yet further embodiment (Fig. 8, not shown) is as Fig. 12 without any overload release means.