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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. [4]
There are many types of valves, and they are most commonly used on automobile, motorcycle, and bicycle tires, but also for many other applications. The most common type is the Schrader valve, but some road bicycles with skinny tires instead use the Presta valve. [5] [6] [7] [8]
Schrader valves consist of a valve stem into which a poppet valve is threaded with a spring attached. They are used on virtually all automobile and motorbike tires and on wider-rimmed bicycle tires. 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. The Schrader valves in the fuel injector rail of many automobiles are used as a quick and easy point to check fuel pressure or connect an injector cleaner cartridge. [9] [10] [11] [12] [13] [14] [15] [16]
Presta valves (also called Sclaverand valves or French valves) are normally only used on bicycles. The stem has a narrower diameter (nominally 6 mm) than the thinnest (nominally 8 mm) Schrader type, and so the bore of the hole in the rim through which the stem passes can be smaller. Has a locknut that needs to be opened to inflate/deflate. [17] [18]
Dunlop valves (also called Woods valves or English valves) were the dominating bicycle valves in the European region and many other countries. As of 2021, Presta valves are just as common in these regions. Dunlop valves are still widely used especially on low to medium-priced bicycles (city and trekking bikes). [19] They can be pumped up with a Presta bicycle pump. [20]
The "Regina Valve" is very similar to the Presta and mostly used in Italy. [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. A threaded rod is enough. By tightening the nut, the valve disc with the conical sealing body is pressed against the valve seat.
Rim drilling:⌀ 6.5 mm
Thread DIN 7756 • outside VG 6×32 •outside VG 5.2×24 at the upper end
Maximum pressure 15 bars.
Many other valves are used only in certain regions or for limited purposes.
Invisible tire valves are different in design from traditional tire valves. An inflator stem is not used; instead, a removable cap on a valve stem embedded in the tire rim is fitted, with only the cap visible. When inflating the tire, the cap is first removed, typically with a coin, and then a "portable" dedicated inflator stem is screwed onto the valve stem. Through the inflator, the tire is inflated as usual.
A valve is a device or natural object that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
A bicycle pump is a type of positive-displacement air pump specifically designed for inflating bicycle tires. It has a connection or adapter for use with one or both of the two most common types of valves used on bicycles, Schrader or Presta. A third type of valve called the Dunlop valve exists, but tubes with these valves can be filled using a Presta pump.
Hydropneumatic suspension is a type of motor vehicle suspension system, designed by Paul Magès, invented by Citroën, and fitted to Citroën cars, as well as being used under licence by other car manufacturers. Similar systems are also widely used on modern tanks and other large military vehicles. The suspension was referred to as Suspension oléopneumatique in early literature, pointing to oil and air as its main components.
The Schrader valve is a type of pneumatic tire valve used on virtually every motor vehicle in the world today. The Schrader company, for which it was named, was founded in 1844 by August Schrader. The original Schrader valve design was invented in 1891, and patented in the United States in 1893.
August Schrader (1807–1894) was a German-American inventor and mechanic. He is known for inventing the Schrader valve.
Hydraulic machines use liquid fluid power to perform work. Heavy construction vehicles are a common example. In this type of machine, hydraulic fluid is pumped to various hydraulic motors and hydraulic cylinders throughout the machine and becomes pressurized according to the resistance present. The fluid is controlled directly or automatically by control valves and distributed through hoses, tubes, or pipes.
The Presta valve is a type of tire valve commonly found on high pressure bicycle inner tubes and is commonly used on tubeless setups. It consists of an outer valve stem and an inner valve body. A lock nut to secure the stem at the wheel rim and a valve cap may also be present.
A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
An air pump is a pump for pushing air. Examples include a bicycle pump, pumps that are used to aerate an aquarium or a pond via an airstone; a gas compressor used to power a pneumatic tool, air horn or pipe organ; a bellows used to encourage a fire; a vacuum cleaner and a vacuum pump. All air pumps contain a part that moves which drives the flow of air. When the air gets moved, an area of low pressure gets created which fills up with more air.
A hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing glycol ethers or diethylene glycol, to transfer pressure from the controlling mechanism to the braking mechanism.
A flat tire is a deflated pneumatic tire, which can cause the rim of the wheel to ride on the tire tread or the ground potentially resulting in loss of control of the vehicle or irreparable damage to the tire. The most common cause of a flat tire is the puncturing of the tire by a sharp object, such as a nail or pin, letting the air escape. Depending on the size of the blowout, the tire may deflate slowly or rapidly.
A tubeless tire is a pneumatic tire that does not require a separate inner tube.
The Dunlop valve, is a type of pneumatic valve stem in use—mostly on inner tubes of bicycles—in many countries, including Japan, Korea, India, Pakistan, Sri Lanka, most European countries, and a number of developing countries. The Dunlop valve has a wider base than a Presta valve, similar enough in size to a Schrader valve to use identically drilled valve holes in rims, but it can be inflated with a Presta valve adapter. The inner mechanism of the valve can be replaced easily, without the need for special tools.
A bicycle tire is a tire that fits on the wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for racing. Bicycle tires provide an important source of suspension, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically the second largest source, after wind resistance, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle.
A tubular tyre, referred to as a tub in Britain, a sew-up in the US, a single in Australia, or just a tubular is a bicycle tyre that is stitched closed around the inner tube to form a torus. The combination is then glued onto a specially designed rim, referred to as a "sprint rim" in Britain, and just a "tubular rim" in the US, of a bicycle wheel.
A tire changer is a machine used to help tire technicians dismount and mount tires with automobile wheels. After the wheel and tire assembly are removed from the automobile, the tire changer has all the components necessary to remove and replace the tire from the wheel. Different tire changers allow technicians to replace tires on automobiles, motorcycles and heavy-duty trucks. New tire and wheel technology has improved certain tire changers to be able to change a low profile tire or a run-flat tire.
The following outline is provided as an overview of and topical guide to tires: