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The wheel trains of clocks are a little more varied, with different numbers of wheels depending on the type of clock and how many hours the clock runs between windings (the "going"). [2] However, the wheel trains of clocks and watches share the same terminology, and are similar enough that they can be described together.
The backward motion of the escape wheel during part of the cycle, called recoil, is one of the disadvantages of the anchor escapement.It results in a temporary reversal of the entire wheel train back to the driving weight with each tick of the clock, causing extra wear in the wheel train, excessive wear to the gear teeth, and inaccuracy.
2. The gear trains used in clocks and watches have multiple stages of wheels and pinions in which the pinions have few leaves. Involute designs for these leaves would be undercut, making them too fragile and difficult to manufacture. 3. A large aspect of the design of watch and clock movements is the minimisation of friction.
Dondi constructed the clock, with its 107 gear wheels and pinions, entirely by hand. No screws were used, and every part was held together by over 300 tapering pins and wedges, with some parts being soldered. Most of the wheels have triangular shaped teeth, although some are blunt-nosed.
Large gears known as wheels mesh with small gears known as pinions. The wheels in a typical going train are the centre wheel, third wheel, and fourth wheel. A separate set of wheels, the motion work, divides the motion of the minute hand by 12 to move the hour hand and in watches another set, the keyless work, allows the hands to be set. Escapement
A rack and pinion has roughly the same purpose as a worm gear with a rack replacing the gear, in that both convert torque to linear force. However the rack and pinion generally provides higher linear speed — since a full turn of the pinion displaces the rack by an amount equal to the pinion's pitch circle whereas a full rotation of the worm screw only displaces the rack by one tooth width.
Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer, or planet, gears or pinions, revolving about a central sun gear or sun wheel. [4] [5] Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear.
A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position by a spiral torsion spring , known as the balance spring or hairspring .