Why is the jack so small that it can lift the car?

Pascal's law (When the external pressure of a liquid in a closed container changes, as long as the liquid remains in its original static state, the pressure at any point in the liquid will change by the same size). In short, in the container At one of the places, the pressure of the small piston is used, and the large piston will produce a force change of the area ratio of the small piston. If the area of the large piston is 10 times the area of the small piston, the force acting on the large piston will increase. It is 10 times larger than a small piston. Pascal is a French physicist。

The working principle of the inflatable jack is to use the exhaust gas of the car to fill the airbag and maintain a certain pressure. This pressure is transformed into a uniformly distributed lifting force through the contact of the airbag and the chassis of the car, so as to achieve the purpose of lifting the car.

The contact area of the inflatable jack and the chassis of the car is much larger than the contact area of the conventional jack and the chassis of the car, so only a pressure of less than 1 atmosphere is required to lift the car. When the engine of a car is working, the pressure in the cylinder is generally not less than 45 atmospheres, which can easily handle the work of inflating the jack, and will not cause any damage to the engine itself. It can be divided into rack jack, screw (mechanical) jack and hydraulic (hydraulic) jack.

1. Rack jack: The rack is lifted by human power through levers and gears to lift heavy objects. The lifting weight is generally no more than 20 tons, which can support heavy objects for a long time. It is mainly used in places where operating conditions are inconvenient or where lower supporting claws are needed to lift heavy objects, such as railway track starting operations.

2.Screw jack: Driven by manpower through the screw pair, the screw or nut sleeve is used as a lifting member. Ordinary screw jacks support heavy objects by the self-locking function of threads. The structure is simple, but the transmission efficiency is low and the return stroke is slow. The thread of the self-lowering screw jack has no self-locking effect, but is equipped with a brake. When the brake is released, the heavy object can descend quickly and shorten the return time, but this jack structure is more complicated. The screw jack can support heavy objects for a long time, and the maximum lifting weight has reached 100 tons, which is widely used. After the horizontal screw is installed in the lower part, the heavy object can also be traversed by a small distance.