Only one complex in this plan is a hydraulic pump, but its layout is also very simple. Its primary moving element is a piston, located in a cylindrical hydraulic chamber. Inside the hydraulic chamber, there is a small spring. In order to make the hydraulic pump work, you must first pull the wrench back, and then push the piston into the hydraulic chamber. The moving piston tightens the tension spring so that when you release the wrench, the piston is pushed out of the hydraulic chamber. The two strokes of the piston into and out of the hydraulic chamber constitute a sound pump cycle.
During the downward stroke, the piston is pushed inward, compressing the volume of the hydraulic chamber, and then pushing the liquid out of the pump. During the upward stroke, the extension spring pushes the piston outward, expanding the volume of the hydraulic chamber, and then sucking the liquid into the pump. When using a plastic pump head with a hood, you need to suck the cleaning liquid from the lower reservoir, and then knead it out of the upper cavity. In order to get all the liquid that flows into the cavity, the pump can only press the liquid up-not the liquid back into the reservoir. In other words, the liquid can only flow through the pump in one direction.
The equipment that accomplishes this function is called a one-way valve. The plastic pump head with hood has two one-way valves in its pumping system: one between the pump and the reservoir and the other between the pump and the nozzle. Generally, the one-way valve between the pump and the reservoir includes a small rubber ball, which is placed lightly in a small sealing cylinder. There is a sharp edge on the edge of the sealing tube, so the rubber ball will not fall from the sealing tube. According to the plan, when you are not pumping water, the ball relies on its own gravity or the elastic force of a small spring to bear against the sealing tube, and then blocks the passage of water. When the piston moves outwards (when you loosen the wrench), the extended hydraulic chamber will draw the small rubber ball away from the sealing cylinder and draw the liquid from below. Because the ball is lifted, the liquid can flow in from the reservoir without being blocked. When you press down the wrench, the external force of the active liquid pushes the ball back to the sealing cylinder, blocking the channel between the pump and the reservoir. Therefore, the liquid under pressure can only flow to the small cavity above.
The one-way valve between the pump head and the nozzle is a cup-shaped device that is placed at the end of the cavity. During the upward stroke, because the pressure in the pump is less than the outside air pressure, the cup-shaped device is tightly attached to the cavity, so air cannot flow from the nozzle. During the downward stroke, the squeezed liquid pushes the cup-shaped device slightly away from the cavity and then flows out of the nozzle. If there is no second one-way valve, the pump system will not be able to suck liquid from the reservoir due to the short suction (no pressure drop). At this moment, the upward stroke will not reduce the air pressure in the pump; it will only draw in more air to maintain the pressure inside the pump.
The second plastic pump head check valve can also be used as a shut-off system. When you tighten the spray head, the cup valve will be pressed tightly against the cavity, so that no liquid can be pressed out. When you unscrew the nozzle, there will be room for the cup valve to move back and forth.