Valve stem

A valve stem is a self-contained valve that opens to admit gas to a chamber (such as air to inflate a tire),[1] and is then automatically closed and kept sealed by the pressure in the chamber, or a spring,[2][3] or both, to prevent the gas from escaping.

In addition to tires, Schrader valves of varying diameters are used in refrigeration and air conditioning systems, plumbing, engine fuel injection, suspension systems, and SCUBA regulators, allowing the user to remove and attach a hose while in use.

Dunlop valves are still widely used especially on low to medium-priced bicycles (city and trekking bikes).

[21][circular reference] The central threaded pin is so short that it does not protrude from the valve tube and therefore cannot be bent.

In order to close the valve tightly, a small, loose nut is placed on this threaded rod with a diameter of only around 1.5 mm and screwed on by hand.