Page:The Kinematics of Machinery.djvu/543

 COMBINED WORK-PIECE AND DRIVER.

521

The special feature of the ram, that the work-piece forms a portion of the driver, is to be found also in some other machines, as, for example, in the Chinese scoop-wheel mentioned in 48 and other wheels resembling it, such as the Noria ( 49), where the machine consists of a main-train (running-gear), having neither director nor regulator. The chains forming the basis of these machines have three links only, the wheel, the water and the piece forming the frame for the one and the channel for the other.

Where the nature of a prime-mover is already known by analysis it is often possible to include it as a whole in the descriptive analysis without impairing the distinctness of the description. In a paddle-steamer, for instance, we may call the engine with its

FIG. 361.

paddle-wheels paired with the water the leading train ; the rudder and its gearing form here a mechanism for guiding the motion of the whole, that is, a director ; a self-acting regulator is seldom applied, there is commonly only an arrangement which can be worked by hand as a stop -gear. The steam-engine itself has its own director and supply, as we have already seen.

The illustrations we have given are sufficient to show how our analysis can be used, and what results it gives. In most of the machines described it would have been useless to apply the old subdivision into receptor, communicator and tool. Any attempt to apply it to (say) the steam-engine, the clock or the loom shows at once that it is absolutely of no help to us. Indeed there has