In [Fig. 2621] is shown a coupling whose parts are shown in [Fig. 2622]. It consists of a cylindrical ring turned true on the outside and bored conical from each end to the middle of its length, as shown. The split cones are bored to receive the shaft and contain a keyway to receive a spline provided in the shaft ends, and are turned on the external diameter to fit the conical borings in the sleeve. Three square bolts pass through the split cones, which, being square, are prevented from rotating while their nuts are being screwed up.
To put the coupling together one split cone is passed over the end of one shaft and the other over that of the other. The sleeve is then put between the ends of the shaft, the position of the shaft adjusted for length and the split cones pushed up into the sleeve; the bolts are then passed through and screwed up. The forcing of the split cones into the conical borings of the sleeve causes the former (from being split) to close upon the shaft ends and grip them equally tight, notwithstanding any slight difference in the diameters of the shaft, there being left between the ends of the split cones sufficient space to allow them to pass through the conical borings sufficiently to close upon the respective ends of the shafts; the pressure being parallel and equal on each shaft end, because when the cone has gripped the largest shaft the whole movement due to screwing up the nuts is transferred to the cone enveloping the smaller shaft, and by reason of the cones fitting, the closure of the holes in the cones is parallel, giving an even grip along the shaft end and an equal amount of grip to each shaft end.
To remove the coupling the bolts are removed, and the sleeve being moved endways the cones open from their spring and relieve the grip upon the shaft.
It is evident that in their passage through the sleeve casing the cones will move with their axial lines true with the axial line of the casing; and it is equally evident that the taper on the cone accurately fitting the taper in the sleeve bore, the closure of the cone bores must be equal; while at the same time the pressure on the two cones upon the respective shaft ends must be equal, because it is the friction of the cone bores upon the shaft ends which equally resists the motion of both, while the pressure applied to the respective cones is derived from the same bolts, and hence is equal and simultaneous in its action.
To loosen this coupling for removal the bolts must be stacked back and a few blows on the exterior of the outer shell with a billet of wood may loosen the coupling; but if not, a wedge or a cold chisel may be driven in the splits of the cones to loosen them, but such wedge or chisel should not have contact with the sides of the split, either near the bore or near the perimeter, for fear of raising a burr.
Fig. 2623.
