446
KINEMATICS OF MACHINERY.
function in every case is the formation of kinematic links, these links having the form C + ...\ ...G+.
FIG. 300.
FIG. 301.
Moveable couplings subdivide themselves into those which are moveable axially, radially, and angularly. Sharp's claw coupling,
Fig. 301, is an illustration of the first kind. It is formed as a prism pair PP~, for the claws of the piece A and B are prismatic, and are so formed that relative motion can take place between them only in tl e direction of the axis of the shafts a and ~b. We may suppose the pieces A and B to be connected to a and b by key-fastenings.*
Oldham's coupling, Fig. 302, is one which is moveable radially. We have already examined this mechanism fully ( 72), and have found it to be a turning cross-block, having the special formula
FIG. 302.
The universal joint, Fig. 303, is an example of a coupling having angular motion. We have in our earlier investigations repeatedly spoken of this train, and in 62 pointed out that it was a conic turning cross-block ((7J<7 t )r. It must not be forgotten that the link C~...L...C~ is omitted from our figure, as is usually the case in representations of the joint.
These examples are sufficient to show that in the moveable
- This coupling is not intended for use as a clutch, but for allowing a or b to move
axially without disturbing the transmission of rotation.
