When using a pump, it is necessary to connect its outlet pipe to the valve of the bicycle tire. The function of the valve is to only allow air to enter the tire from the pump, and not to allow air to flow from the tire into the pump.
The principle of the old leather cup pump: there is a gap between the piston of the pump and the wall of the pump. There is a rubber bowl concave downward on the piston. When the piston is pulled upward, the air volume under the piston increases, the pressure decreases, and the piston The air above is squeezed from around the rubber bowl to the bottom. When the piston is pressed down, the volume of air under the piston is reduced and the pressure is increased, so that the rubber bowl is pressed against the wall of the cylinder to prevent air from leaking above the piston and continue to press the piston down When the air pressure is sufficient to push the valve core of the tire, compressed air enters the tire. At the same time, the air outside the barrel enters the piston from the gap at the upper end of the barrel.
The new type of pump with sliding outer tube is the simplest one-way valve. When the outer tube is lifted up, air enters the air cylinder through the small hole in the middle sleeve at the lower end of the outer tube of the air cylinder.When the handle is pressed down, the gas will enter the air cylinder through the one-way valve set at the top of the inner tube Inner tube, follow the hose to enter the valve of the tire!
When the handle is raised again for the second time, the one-way valve is closed, and when it is pressed again, the air bursts the one-way valve into the tire.
This is the process of round trip.