The mechanical watch is powered by the elasticity of the clockwork. When the mainspring is full, its torque is greater. As the watch is transported, the mainspring becomes slack, and its torque gradually decreases. From winding the watch to 24 hours, the torque output of the watch is stable. At this time, the travel time is relatively accurate and the error is small. After more than 24 hours, the spring torque will suddenly decrease and the travel time error will increase.