Clock Principle

- Apr 26, 2019-

Clocks and watches have a wide range of applications and many varieties. They can be classified according to vibration principle, structure and use characteristics. According to the principle of vibration, it can be divided into clocks and watches which use lower frequency mechanical vibration, such as pendulum clock and pendulum wheel clock; clocks and watches which use higher frequency electromagnetic oscillation and quartz oscillation, such as synchronous electric clock and quartz clock; mechanical watches such as mechanical alarm clock, automatic, calendar, double calendar, spring and other mechanical watches according to their structural characteristics; electrical and mechanical watches such as pendulum clock and electric pendulum wheel clock. Electronic, such as pendulum wheel electronic clock, tuning fork electronic clock, pointer and digital display quartz electronic clock, etc.






Mechanical clocks and watches have many structural forms, but their working principles are basically the same. They are all composed of driving system, transmission system, escapement governor, pointer system and upper needle system.


Mechanical clocks and watches use the spring as the power of the driving system, through a group of gears to drive the escapement governor; then the escapement governor controls the speed of the transmission system in turn; while driving the escapement governor, the transmission system also drives the pointer mechanism, the speed of the transmission system is controlled by the escapement governor, so the pointer can indicate the time on the dial according to certain rules. The upper dialing needle system is a mechanism for tightening the spring or pulling the pointer.






In addition, there are some additional mechanisms, which can increase the functions of clocks and watches, such as automatic latching mechanism, calendar (double calendar) mechanism, alarm device, moon phase indication and measuring time mechanism, etc.






The prime mover system is a mechanism for storing and transferring working energy. It is usually composed of a carton wheel, a carton cover, a bar shaft, a hairspring and an outer hook of the hairspring. In the free state, the spring is a spiral or S-shaped spring with a small hole at its inner end, which is sleeved on the hook of the bar shaft. Its outer end is hooked on the inner wall of the barrel wheel through the outer hook of the barrel. When winding, the winding is tightened on the axle by rotating the bar axis through the needle system of winding. The elastic action of the spring makes the carton wheel rotate, thus driving the transmission system.






The transmission system is a set of transmission gears that transmit the energy of the original system to the escapement governor. It is composed of two wheels (center wheel), three wheels (passing wheel), four wheels (second wheel) and escapement gear tooth shafts. The wheel blade is the driving gear, and the tooth shafts are the driving gear. The tooth profile of the clock transmission system is mostly based on the principle of theoretical cycloid, and the modified cycloid tooth profile is made after modification.






The escapement governor is composed of escapement mechanism and vibration system. It relies on the periodic vibration of the vibration system to keep the escapement mechanism moving accurately and regularly intermittently, so as to achieve speed regulation. Fork-tile escapement mechanism is one of the most widely used escapement mechanisms. It is composed of escapement wheel, escapement fork, double disc and limit nail. Its function is to transfer the energy of the original system to the vibration system so as to maintain the vibration system to vibrate at the same amplitude, and to transfer the vibration number of the vibration system to the indicating mechanism, so as to achieve the purpose of measuring time.






The vibration system is mainly composed of a pendulum wheel, a pendulum shaft, a hairspring, a movable outer pile ring, a fast and slow needle, etc. The inner and outer ends of the hairspring are fixed on the swing shaft and the swing splint respectively. When the pendulum wheel starts to swing when the external force deviates from its equilibrium position, the hairspring will be twisted to produce potential energy, which is called restoring moment. The escapement mechanism completes the above two actions. The vibration system swings in the opposite direction to complete the other half of the vibration cycle under the action of the potential energy of the hairspring. This is the principle of the escapement governor working continuously and repeatedly during the operation of mechanical clocks and watches.






The function of the upper needle-pulling system is the upper needle-pulling system and the needle-pulling system. It consists of handle head, handle shaft, vertical wheel, clutch wheel, clutch rod, clutch rod spring, pull gear, press spring, needle wheel, span wheel, time wheel, dividing wheel, large steel wheel, small steel wheel, pawl, ratchet spring, etc.






The top bar and the dialing needle are realized by the handle head part. When winding, the vertical wheel and clutch wheel are in meshing state. When turning the handle head, the clutch wheel drives the vertical wheel. The vertical wheel passes through small and large steel wheels to tighten the winding of the bar shaft. The pawl prevents the big wheel from reversing. When the needle is pulled out, the handle head is pulled out, the pull gear rotates on the pull shaft and pushes the clutch rod, so that the clutch wheel and the vertical wheel are detached and meshed with the pull pin wheel. At this time, when the handle is rotated, the needle pulley drives the time wheel and the dividing wheel through the cross-wheels, so as to achieve the purpose of correcting the time and dividing needle.






Clocks and watches are required to travel accurately, stably and reliably. However, some internal factors and external environmental conditions will affect the travel time accuracy of clocks and watches. 内部因素包括各组成系统的结构设计、工作性能、选用材料、加工工艺和装配质量等。 For example, the stability of the winding moment, the smoothness of the transmission system and the accuracy of the escapement governor all affect the travel time accuracy.






External environmental conditions include temperature, magnetic field, humidity, air pressure, vibration, collision, use location, etc. For example, the change of temperature will cause the change of lubricating oil and yarn performance of pendulum wheel in clocks and watches, which will lead to the change of travel time performance; when the magnetic field intensity of environment is greater than 60 Oster, it will cause the magnetization of some parts to slow down; humidity will cause oxidation and corrosion of some parts, etc.