Page:The Kinematics of Machinery.djvu/318

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KINEMATICS OF MACHINERY.

or more shortly,

C+ ... || ... (C) ... || ... (<7) ... J. ... (P) ... _L ... C- or in its contracted form (C^'P- 1 -), In this most important chain the link c slides along a straight line instead of swinging in an arc as in (C"). We may call it shortly the cylindric slider-crank chain, or simply the slider chain. We have now to examine the four mechanisms corre- sponding to its four positions.

The mechanism (C' 3 'P i -) d. If we place the chain on d y as in Fig. 216, the link c slides backwards and forwards as the crank rotates, and we have before us one of the most familiar of mechanisms, one which appears constantly in direct acting steam-engines, in pumps, and in slotting and so many other machines. The link c we shall call the block, and the link d the slide, when we have occasion to name them. The whole mechanism we may call a turning slider- crank, on account of the characteristic rotation of a. In its applications to the steam-engine the block c becomes the driving link, so that the general formula

(CIP-^Y 8 -ives us the special formula (C^P^fi. In the other applications of it which we mentioned the crank a is the

driver, their special formula is therefore (G y 3 P- 1 -)*. The complex motion of the coupler I can be exactly determined by its centroids,

FIG. 215.

FIG. 216.

but these we must here leave unexamined, merely noticing that they are symmetrical about the axis 31.

The mechanism (C 3 P- L ) b. Following the order formerly adopted let us now place the chain on &, Fig. 217.* The crank a now

screw adjustment which is shown in Fi#s. 11 and 180.
 * In Prof. Reuleaux's models for the (6' 3 P-L) mechanisms he uses the stand with