Fig. 2630.
In [Figs. 2627] to [2630] are shown a side elevation and sectional view of another form of shaft coupling. a is the sleeve, b b nuts on the ends of the sleeve, and c c cones fitting taper holes in the sleeve. These cones are split, as shown in [Fig. 2629], to permit them to close upon the shaft ends. The shaft ends themselves are matched with a half dovetail, as in [Fig. 2630], which dispenses with the employment of a key.
In coupling shafts of different diameters it is usual to reduce the diameter of the end of the larger to that of the smaller shaft, and to employ a size of coupling suitable for the smaller shaft; but in this case it is necessary that the coupling be placed on the same side of the hanger or bearing as the smaller shaft, otherwise it is obvious that the strength of the larger would, between its bearings, be reduced to that of the smaller shaft.
The couplings for line shafting are usually placed as near to the bearings or hangers as will leave room for the removal of the couplings by sliding them along the shaft.
The couplings on the length of shaft receiving power from the motor are placed outside the bearings, hence on the succeeding lengths there will be one coupling between each pair of bearings, the couplings being in each case as close to each bearing as will allow the coupling to be moved towards the bearing sufficiently to permit the length to be removed without disconnecting the adjacent length from its bearings.
Fig. 2631.
[Fig. 2631] represents a very superior form of coupling for line shafts. The ends of the line shaft are reduced to half diameters as shown, and lapped with a horizontal joint at an angle to the axis of the shaft as denoted by the dotted line, which prevents end motion; the ends of the shaft and their abutting surfaces are dovetailed, as shown a and b, and, therefore, perform driving duty. A sleeve envelops the whole joint and is secured by a key. This coupling accomplishes all that can be desired, but requires very accurate workmanship, and on this account is expensive to make.