Trigger Sprayer pumps have a really straightforward design and work with several parts to make sure the pumping action delivers liquid in the bottle as a spray. The trigger lever, once pulled using a few fingers activates a small pump. This pump is attached to a plastic tube that draws cleaning fluid from the bottom of the reservoir inside the bottle. The pump forces this liquid down a narrow barrel and out a small hole at the spray valve.
Inside the shroud, there is a small spring that compresses the fluid once pulled back by the trigger. The moving piston compresses the spring, so when you release the trigger, the piston is pushed back out of the gasket. These two strokes of the piston move the cylinder out again and contribute to the entire pump cycle.
This extraction motion shrinks the cylinder and forces the fluid out as a one-way system. Once the trigger is released, the motion allows the processes to be repeated without any delivery problems. Slightly different designs are used depending on the pump type and delivery solution.