The common types of jacks in daily life include rack jacks, screw jacks, and hydraulic jacks. Among them, the screw jack is essentially just a force transmission device, and in actual use, it is not as labor-saving as the hydraulic jack.

The key to the effortless use of hydraulic jacks lies in the lifting system composed of their Pascal principle. When a small force is applied from the outside, the small piston in the system will generate a certain pressure, and this pressure increment will be transmitted to the large piston through the enclosed liquid, thereby outputting a lifting force much greater than the input force.

Although the principle is slightly complex, in simple terms, the larger the area ratio of the large piston to the small piston in a hydraulic jack, the easier it is to lift. However, correspondingly, the displacement generated by each downward pressure of the small piston is also relatively small, and the larger the height that the large piston needs to rise or fall, the more pressing times and operation time will significantly increase, at the cost of time.

It is worth noting that whether it is a pulley, a slope, a lever, or a hydraulic system, these machines all follow the basic principle of "saving effort but not power". They do not create additional energy, but instead use a 'divide and conquer' approach to convert the large force output that originally needed to be completed at once into small force input that can be applied over a longer period of time, thereby helping us complete seemingly impossible heavy objects that cannot be lifted directly. Essentially, the total effort we put in does not decrease, but rather we approach it in a more controllable way.