When plate couplings are constructed as in [Fig. 2617], the removal of a section involves either the driving back of one-half of the coupling so that the other half will clear it, or else the moving endwise of the whole line to effect the same object.
With a plate coupling the half coupling on one end of the shaft must be removed when it is required to put an additional pulley on the shaft, unless, indeed, a split pulley be used, whereas with a clamp coupling, such as shown in [Fig. 2621], the half coupling at each end may be slacked and moved back, one end of the shaft released, a solid pulley placed on the shaft and the coupling replaced, when it will run as true as before, and the pulley may be adjusted to its required position on the length of shafting.
It is to be remarked, however, that a well-made plate coupling, such as in [Fig. 2618], makes a good and reliable permanent job that will not come loose under any ordinary or proper conditions.
Fig. 2625.
Fig. 2626.
In [Fig. 2625] is shown a patent self-adjusting compression clamp, which is peculiarly adapted to connect shafting that is of proper gauge diameter. It consists of a sleeve a made in two halves, each embracing nearly one-half of the shaft circumference and being bored parallel and slightly smaller than the diameter of the shaft ends. Over this sleeve passes at each end a ring d e, bored conical and fitting a similar cone on the external diameter of the sleeve. On each end of the sleeve is the nut f g, which by forcing the cone ring up the taper of the sleeve causes the two halves of the latter to close upon and grip the shaft. For shafts less than two inches in diameter there are provided in the sleeve two pins to enter holes in the shaft ends in place of keys, but for sizes above that keys are employed. All parts of this coupling being cylindrical it is balanced. The separate parts of this coupling are shown in [Fig. 2626].