Wagon bolts refer to larger diameter screws; in this context, screws are much smaller in diameter compared to bolts. Wagon bolts have no head and are sometimes called double-end studs. Both ends of wagon bolts are threaded, with no threading in the middle, leaving a smooth shaft in the center. They are used in large equipment such as reduction gear frames. In actual use, external loads can cause vibrations and temperature effects, leading to reduced friction. Over time, the threaded connections can become loose and fail. Therefore, regular maintenance of wagon bolts is necessary. Wagon bolts or anchor bolts may experience issues under prolonged mechanical friction, so when problems arise, the engine oil pan should be removed to carefully inspect the condition of the engine bearings and check for excessive gaps between them. If gaps are too large, they should be replaced promptly. When replacing wagon bolts, it is also advisable to replace the connecting rod bolts.