Читать книгу The Modern Clock. A Study of Time Keeping Mechanism; Its Construction, Regulation and Repair онлайн

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Suspensions.—Suspensions are of four kinds, cord, wire loop, knife edges and springs. Cords are generally of loosely twisted silk and are seldom found except in the older clocks of French or Swiss construction. They have been entirely displaced in the later makes of European manufactures by a double wire loop, in which the pendulum swings from a central eye in the loop, while the loop rocks upon a round stud by means of an eye at each end of the loop. The eyes should all be in planes parallel to the plane of oscillation of the pendulum, otherwise the bob will take an elliptical path instead of oscillating in a plane. They should also be large enough to roll without friction upon the stud and center of the loop, as any slipping or sliding of either will cause them to soon wear out, besides affecting the rate of the pendulum. Properly constructed loops will give practically no friction and make a very free suspension that will last as long as the clock is capable of keeping time, although it seems to be a very weak and flimsy method of construction at first sight. Care should be taken in such cases to keep the bob from turning when regulating the clock, or the effect upon the pendulum will be the same as if the eyes were not parallel.