Bicyclists use bicycle pumps on a very regular basis, but most probably never stop to think how they actually work. The purpose of the bike pump is to force air out of the valve and into your tire to increase the pressure to the appropriate level. Bike pumps use different means to do this, including hand pumping, foot pumping and CO2 cartridges. The most common means is by manual hand pumping. Here we'll look at exactly how a floor pump works.
Intake and Release
The floor pump is basically just an air piston. The long metal or plastic shaft that stands between the base and the handle serves to hold air. When you pull the handle upwards air is sucked in through an intake valve and the piston is full of air. When you push back down on the handle, the air is pushed out of the piston, into the hose and out of the fill valve. The handle that you hold is attached to a long, thin rod that goes down into the main pump shaft. At the end of this rod, inside the pump, is a plunger assembly that creates an airtight seal so that when you push down, all air is pushed out the hose.
Bicycle pumps use several different valve types, primarily Schrader and Presta. These two types of valves correspond to the matching valve on the bike tube. Bike tubes can be purchased in either Schrader or Presta varieties. When you put the pump valve onto the tire valve and lock it in place, it allows the air exiting the pump to be pushed directly into the tube, rather than spraying out into the open atmosphere. Quality floor pumps have a pressure gauge attached, which allows you to read the tire pressure currently in your tube and pump to the desired pressure level.