Patent GB-489763-A (GB)
Title: Improvements in cam-actuated transmission devices
IPC: F16H25/20
Filed: 1936-12-31
Abstract: 489,763. Mechanical presses. FIORENTINO, A. Dec. 31, 1936, No. 35867. [Class 87 (ii)] [Also in Group XXIV] In cam mechanism, applicable to presses &c., the cam effects a complete driving stroke and the cam faces are then returned to operative position, ready to make a further driving stroke, by screw and nut or worm and wheel means, the worm, when used, being in two parts acting also alternately as racks driven by the cam means to rotate the worm-wheel, then acting as a pinion, to drive the driven shaft to which it is secured. As applied to a wine or like press, Fig. 1, a screw-threaded member 1 is fixed and a plate 2 is adapted to exert the thrust. A casing 3, adapted to be rotated by a pawl acting upon a part 4, is mounted on the plate 2 and has lugs to receive tenons 5 on a cam ring 6 carried on bearings 16 in a race 17 fixed to the plate 2. The upper face of the ring has a series of inclines 7, Fig. 2, which coact with an equal number of balls 8 in a cage 9, the balls in turn coacting with a race 11 fixed to a nut 10 carried by the member 1. Between the cage 9 and nut 10 are a number of friction shoes 12 lightly-pressed by springs 14. A number of lugs 22 connected to the casing 3 by spring-pressed friction means 24 are connected by springs 20 with corresponding lugs 21 on the nut 10. A second nut 18 carried by the member 1 below nut 10 is connected to the ring 6 by lightly-pressed friction shoes 12a and is normally screwed down into contact with the plate 2, the friction with the ring 6 being sufficient for this, the pitch of the screw thread being made greater than the slope of the cam inclines 7. In operation, rotation of the casing 3 rotates the ring 6, and the nuts 10, 18 are easily moved down the member 1 until a resistance to plate 2 is encountered. When this occurs, the thrust is transmitted to the nut 10 through balls 16, ring 6, and balls 8 and the latter ride up the inclines 7. Consequently the plate 2 is forced downwardly and, at the same time, the springs 20 are stretched and the nut 18 is moved down into contact with plate 2 by the shoes 12a. When the tops of the inclines 7 have passed the balls 8 and the latter roll down the other side, they leave the race 11 which is thus relieved of load and the stretched springs 20 pull the nut 10 round and bring the race 11 again into contact with the balls 8 ready for the thrust of the next cam incline and during this movement of the nut 10, the nut 18 is moved down against the plate 2 to prevent its return. Thus the depression of the plate 2 and the rotation of the nut 10 occur alternately. To' move the plate 2 in the upward direction, a pin 25 is inserted through bores in the casing 3 and nuts 10, 18, the whole then being moved as a single nut. The plate 2 may be fixed and the threaded member I moved. In a modification, Fig. 3, a more uniform movement is obtained by providing two nuts 2, 3 actuated by a ball and incline alternately. Each nut has a race 16, that for the nut 2 coacting with balls 4 and that for the nut 3 with balls 5, the balls 4, 5 being staggered angularly. The balls may be enclosed in cages, or run in grooves in the inclines 17, 18 which are formed on a ring 6 carried by a casing 9 and supported by balls 7 on a thrust plate 8. The nuts have extensions 2a, 3a against which friction shoes 10 are lightly pressed by springs 12, the shoes being housed in recesses in the casing 9 and the ring 6. In operation, assuming plate 8 to be fixed and the casing to be rotated, both nuts will move as one over the member 1 until a thrust is encountered, whereupon the balls will ride up the inclines. If balls 4 ride up, the nut 2 will be under load and, together with the member 1, will be moved upwardly, during which movement the nut 3 will be moved by friction down the member 1. When balls 4 run down the inclines, the balls 5 will ride up and lift the nut 3 and member 1, the nut 2 being at the same time moved by friction down the member 1 ready for the next thrust. The pitch of the screw thread must be such that the free nut will move a distance down the thread equal to twice the height of the inclines. In a modification, Fig. 6 (not shown), for acting in opposed directions against a thrust, two nuts are employed and each nut has two races one on the nut and the other on an annular ring carried by arms, the arms of one nut being arranged in the spaces between the arms of the other nut, the races facing in opposite directions. An application to a system resembling a worm and worm wheel is shown in Fig. 9. A wheel 26 is engaged by a split worm 27 comprising parts 27a, 27b of which 27a is integral with a shaft 28 having a flange 29, and 27b is integral with a sleeve portion having a flange 36. The flanges are acted upon alternately by balls 30, 37 coacting with inclines on a member 31 rigid with a casing 32 and rotatable by a shaft 35. The parts 27a, 27b are connected to the member 31 and casing 32 by friction shoes 38. When a ball 30 is raised by its incline, part 27a moves axially and pushes round the wheel 26, the part 27b, which is relieved of load, being rotated to bring it into contact with its balls 37 and vice versa. In a modification, Fig. 10 (not shown), the worm wheel is operable in both directions, the arrangement being particularly applicable to the steering of motor vehicles. In Fig. 12, a nut 45 is fitted on two screw-threaded members 46, 47 bearing on members 48, 49 having the cam surfaces and connected to the members 46,47 by friction shoes 50. The balls 51 bearing on flanges 46a, 47a are held in cages 52 geared together by teeth 53 and the members 48, 49 are also geared by teeth 54 to a driving member 55. The members 46, 47 are lifted and rotated alternately. The pitch of the screw thread must be at least twice that of the cam inclines. A similar principle is applicable to the worm and worm wheel system.