Patent GB-323288-A (GB)
Title: Improvements in or relating to flexible couplings
IPC: F16D3/56
Filed: 1928-10-11
Abstract: 323,288. Thomas, C. 0. Oct. 11, 1928. Shaft couplings; securing pulleys, toothed wheels, &c. on shafts; universal joints.-In universal and other flexible couplings for shafts or for securing pulleys, toothed wheels, &c. on shafts, concentric members, with or without radial clearance, are formed with mating axial grooves, drive being transmitted by elliptical or semielliptical springs engaging the grooves and arranged to tend to be straightened and equally stressed under torque. The male and female members 21, 22, Fig..2, have respectively grooves 25, 29, the grooved part 28 of member 22 being secured to a flange 27 by bolts 32, which may also serve to secure an end ring 31. Where clearance 30 is provided between the part 28 and the grooved flange 24 of member 21 to allow misalignment, the hub 23 is channelled at 33 to accommodate the ring 31, the ring 31 serving positively to limit the misalignment. The flange 24 may, however, be partly spherical, as shown at 40, Fig. 7, to engage the part 28, which, if end thrust is to be transmitted, may form a spherical socket. The springs 35 are preferably supported in annular channels 34 in the parts 27, 31 and comprise each two bowed leaves 36, Fig. 4, with bent tails 37 conforming to the channels. The leaves 36 may be separate or riveted &c. together. The bent-back parts 38 of the tails 37 and the contacting free ends of the leaves 36 may be chamfered at 39 to facilitate assembly. Due to the clearance 30, the springs 35 are tilted as well as flattened under torque, being twisted due to the engagement of the tails and channels; the flaring of the grooves 25, 29, shown to an exaggerated extent in Fig. 6, facilitates this action and prevents localization of pressures. For greater misalignment, the arrangement is duplicated, as shown in Fig. 7, the female members 28a cooperating with spherically-surfaced male members 23a and preferably holding between them a divided ring 41 provided with two channels 34. Two couplings as in Fig. 2 may be connected by an intermediate shaft, and where the malemember flanges 24 are spherical, the remote ends of the hubs 23 may be concentrically spherical to a.Ilow transmission of end-thrust. The grooves may be longitudinally flared to accommodate considerable misalignment. Fig. 8 shows means for coupling a pulley or gearwheel 46 to its hub 47, the end rings 51 secured to one member being a running fit on the other. Small pinions may be mounted on an extension of one end ring, in order that the springs 35 may lie on a sufficiently large pitch-circle, and the other end ring may have a dust-excluding washer, Fig. 9 (not shown). The springs, which have a " rising characteristic " due to progressive shortening under load, provide a yielding drive between the torque necessary to initiate flexure and that sufficient to flatten them. For greater flexibility, several sets of springs may be arranged in axial or other series, or two or more couplings as shown in Fig. 7 may be connected in series. Contact of the tails 37 with the adjacent leaves 36 acts to distribute the load evenly, and the friction of the springs in the channels 34 damps out oscillation. The coupling may be used in marine double-reduction gearing.