What is the working principle of a retrograde watch?

　　The retrograde function is essentially optional; it cannot display more information than the time, nor does it make the watch's timekeeping more accurate. What is the principle behind a retrograde watch making time flow backwards?

　　The principle of a retrograde watch

　　STEP 1: The snail-shaped jump cam and the retrograde lever control the retrograde minute or second hand. The snail-shaped jump cam rotates clockwise, while the retrograde lever moves counter-clockwise along the gears. The retrograde second or minute hand on the dial moves towards the bottom of the fan-shaped scale.

　　STEP2: Gear disengagement after time completion. When the jump cam reaches the apex of the snail shape and the retrograde lever reaches the bottom of the gear, the snail-shaped jump cam disengages from the retrograde lever. At this point, the retrograde second or minute hand on the dial has reached the end of the fan-shaped scale.

　　STEP3: Retrograde action recoil. After disengagement occurs, the spring next to the retrograde lever exerts a counter-force, instantly snapping the retrograde lever and the jump cam back to their original positions. At this point, the retrograde second or minute hand on the dial returns to the origin point to begin the first step of the mechanical operation again.

　　However, without understanding scientific terms like 'snail-shaped jump cam' and 'retrograde lever', anyone would likely be confused by this description. In short, regarding the principle of retrograde, just remember one thing: the key component in a retrograde watch is a jump cam, which looks like a Roman hat when viewed from the side. Its existence allows the hands on the dial to instantly return to their starting positions. While the principle is simple to understand, achieving it perfectly is not easy. The problems arise from two points.

　　1. Retrograde watches experience frequent internal impacts, which can lead to metal fatigue. The jump cam recoils very frequently, and at the moment of recoil, stress is highly concentrated. Therefore, metal fatigue and faults are more likely to occur in retrograde components under repeated motion compared to other mechanical structures. It is like a child trying to bend a piece of wire; it does not take much force, just repeated bending in the same spot.

　　2. The retrograde return also requires time, and this negligible time accumulates over the long term, causing errors. You can imagine how bending a wire in a watch affects other components; it either causes wear or deformation. At this point, the time in the retrograde section will show an error, and most cases manifest as delayed jumping, i.e., losing seconds.

　　Of course, these two problems are trivial in the eyes of master watchmakers. By using superior metal materials and reducing the kinetic energy of the impact, the problem of metal fatigue can be well resolved. Errors are even simpler; the time for the instantaneous return is fixed, so one only needs to calculate the time for each return and correct it during the design phase. Therefore, what the master truly cares about is how to achieve more grandeur within a limited space through the retrograde function.