7. Key; such as those of the organ, flute, etc.
Other names are derived from peculiar shape, application, mode of actuation, etc.
A cock is a faucet or rotary valve usually taking its name from its peculiar use or construction, as:—
Blow-off cock,
Cylinder-cock,
Feed-cock,
Four-way cock,
Gage-cock,
Oil-cock,
Self-closing cock,
Steam-cock,
Stop-cock,
Three-way cock,
Try-cock,
Water-cock, etc.
Note.—The above classification is that made by E. H. Knight, Civil and mechanical Engineer, etc., and author of Knight’s Mechanical Dictionary. He adds: “The heart is created upon the principles of hydraulics, and is furnished with a valve. Harvey deduced the circulation of the blood from Aquapendente’s discovery of the valves in the veins.”
As may be judged by the preceding paragraphs, giving the names derived from their mechanical and other uses of several only, of a great many varieties of valves, it were vain to attempt a complete list of these devices; it may be said however that the whole system of modern mechanism would be, almost, if not quite, a failure, if they were not used.
Hence, the student will do well to familiarize himself with the valve movements sure to be found in every combination of industrial and mechanical forces.
A few illustrations of the adaptation of valves of various designs to useful purposes now follow.—
A combined throttle and quick closing trip valve is shown in Fig. [609], page 336; this is made by Schutte & Koerting Co., Philadelphia; this apparatus is designed to fill the requirements of an emergency shut-off; the valve is balanced and operates as stop and throttle. The object of balancing the valve is to remove the strain from the spindle, so that its operation can be effected quickly and with the least effort. The piston above the valve is not tight fitting, and contains a small auxiliary or pilot valve attached to the spindle, which opens in advance of the opening of the main valve; thus the pressure above the piston and below the valve is equalized; little effort is now required to lift the main valve, at the same time the pilot valve, E, answers the purpose of a by-pass.