Hydraulic jack is a rigid lifting component that can lift several tons of heavy objects to a high place by gently shaking the handle with human power. It has become a commonly used light and small lifting tool in industries such as transportation and construction. Although human power is a part of its power source, the mechanical oil added inside the jack is the true source of energy for the "strongman".

Sometimes when we use hydraulic jacks, we find that no matter how we shake them, the top of the jack and the heavy object remain stationary, causing the heavy object to fail to reach the set normal height. One of the reasons for this malfunction is the lack of mechanical oil, so we can simply add oil.

The question is whether we need to drop the hydraulic jack onto the ground to add oil beforehand, or can we add oil directly during the lifting process? This issue needs to be approached through a specific problem specific analysis approach. Based on operational experience, when using, you can simply unscrew the oil injection hole and add mechanical oil. If the method works, it means that the weak lifting is caused by insufficient oil. If it still cannot be lifted, it is necessary to lower the jack and check the sealing ring and other components.