Non-Aligned Couplings
Non-aligned couplings are used to transmit power between two shafts which are not coaxial. The following are the examples of non-aligned couplings.
1. UNIVERSAL COUPLING (HOOKE'S JOINT): It is a rigid coupling that connects two shafts, whose axes intersect if extended. It consists of two forks which are keyed to the shafts. The two forks are pin joined to a central block, which has two arms at right angle to each other in the form of a cross. The angle between the shafts may be varied even while the shafts are rotating.
2. OLDHAM COUPLING: It is used to connect two parallel shafts whose axes are at a small distance apart. Two flanges, each having a rectangular slot, are keyed, one on each shaft. The two flanges are positioned such that, the slot in one is at right angle to the slot in the other. To make the coupling, a circular disc with two rectangular projections on either side and at right angle to each other, is placed between the two flanges. During motion, the central disc, while turning, slides in the slots of the flanges. Power transmission takes place between the shafts, because of the positive connection between the flanges and the central disc.
3. CUSHION COUPLING: One of the most commonly used flexible couplings now-a-days is the cushion coupling. The H.P rating of these couplings for various speeds, range from 0.2 to 450. The tyre of the coupling is made of natural and synthetic rubber, impregnated with canvas or rayon. The hubs are made of CI or steel.
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