Watch, as a consumable exists, in the design has taken into account the situation of resistance to external interference, including shock; The shock-proof performance of the watch not only refers to bumps, but also includes acceleration overload and impact, which often occurs in sports and production activities.

From the evolution of the clock to the watch, not only the volume has become smaller, mainly in the travel accuracy and anti-interference improvement, it has used the balance wheel, so it can be carried; But antique clocks or pocket watches are very delicate, they can not afford to hurt, the external vibration and impact is very easy to make its escapement and balance with the problem; For this reason, after about 200 years of improvement, people have tried various forms of escapement, and modern watches are basically using lever escapement.

Represented by the anchor lever escapement, it only works reliably because it has two points: (1) the mechanism has traction, and the escapement wheel teeth cut into the fork tile of the escapement fork at an Angle, which will make the fork body of the escapement fork close to the limit nail, and will not move; (2) There is a safety design, even if there is an external force to make the escapement fork move, there is a safety measure between the safety pin of the escapement fork head and the lower disk of the balance wheel (safety disk), will block the escapement fork continue to move, and let it reset under the action of traction torque; Another point is that there is also a safety between the balance wheel disc pin and the escapement fork, once the gap between them is exceeded, it will block, in short, it can not let the escapement fork escape its correct position.

But all these insurance is not foolproof, some watches in the severe vibration impact, or to go wrong, the main and common problem is the occurrence of reverse pendulum. The so-called reverse pendulum is also called the back pendulum, these are commonly known, the real meaning is that the escapement fork out of the correct position, jump to the other side; It turned out that it was also good with the balance wheel like brothers, but in the outside interference, it turned over and betrayed the balance wheel in an instant.

The vibration force that can keep the balance wheel away from the escapement fork is the most powerful (most of it is the force along the direction of 6 to 12 characters of the dial), the upper and lower shockproof device in the watch movement will produce radial movement, resulting in a reasonable safety gap is no longer, for example: The escapement fork should have stayed on the left side, but under the action of external forces, it was not constrained by the safety mechanism, it jumped to the right side, and the shock of the balance wheel did not respond. When it came around, it should have hit the inside of the escapement fork to drive the movement of the escapement fork, but this time it hit the outside of the escapement fork and could not enter the fork again. Escapement and vibration system did not cooperate, which is a classic infarction, the watch suddenly stopped.

Watch in the shockproof experiment, but also with 3KG impact hammer hit the watch (impact hammer arm length 50CM), the instant impact speed of up to 4.43m/s, this experiment is very strong, but many shocks encountered in life may be greater than it. Watch backswing has a feature, no matter how you shake the watch, even the second hand is motionless, belongs to the dead stop, this is different from the general watch stop, if it is the cause of the stop watch, the second hand can walk at least two steps or swing before and after the shake.

If it is a watch that is backed through the back cover, then you keep rotating and shaking the watch, look at the balance wheel of the watch, it is basically motionless, or can only swing a little in one direction. Repair the fault of the back of the watch is very easy, remove the pendulum splint and re-put the pendulum to solve, which belongs to the kind of immediate effect, the repair master loves to do this job. However, the frequent occurrence of the phenomenon of the back of the watch, can be noticed, it must be the escapement of the insurance gap problem, should change the escapement fork or check and reduce the escapement points (mainly between the fork nail and the insurance disc) of the insurance gap.