TABLE OF CONTENTS A machine is a combination of bodies which have definite for, and the strength to maintain that form. These bodies or machine members are so shaped and connected that they can move upon each other, but only in a particular way. Freedom for relative motion of parts differentiates the machine from the structure; constraint to a definite relative motion makes it more than a random assemblage of connected bodies.
Regularly one member (more extensive than the others) is fixed or basal as the frame of the machine, upon or within which the moving members function. Commonly one of these receives an input of driving force and acts as driver; this force, or the work of which it is a factor, is transmitted through the machine, with change in force and velocity and some loss due to friction; and by a final or driven member, at the place of output, force or work is applied against a useful resistance or to a useful effect.
The members of the engine outlined in Fig. 13.1 are frame or bed 1, piston and slide 2, connecting rod 3, and crank and shaft or crank shaft 4. The piston is driver, receiving total gas pressure P. Through the connecting rod, by means of its total lengthwise stress S, the driving effect is carried over to the crank pin, becoming active in tangential component T. The shaft...
