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Kick Scooters
A kick scooter (also referred to as a push-scooter or scooter) is a human-powered street vehicle with a handlebar, deck, and wheels propelled by a rider pushing off the ground with their leg. Today the most common scooters are made of aluminum, titanium, and steel. Some kick scooters made for younger children have 3 to 4 wheels (but most common ones have 2 wheels) and are made of plastic and do not fold. High-performance kickbikes are also made. A company that had once made the Razor Scooters revitalized the design in the mid-nineties and early two-thousands. Three-wheel models where the frame forks into two decks are known as Y scooters or trikkes. Motorized scooters, historically powered by internal combustion engines, and more recently electric motors, are self-propelled kick scooters capable of speeds sometimes exceeding . Models and history Early scooters Kick scooters have been handmade in industrial urban areas in Europe and the United States since the 1920s or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball Bearings
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit the loads through the balls. In most applications, one race is stationary and the other is attached to the rotating assembly (e.g., a hub or shaft). As one of the bearing races rotates it causes the balls to rotate as well. Because the balls are rolling, they have a much lower coefficient of friction than if two flat surfaces were sliding against each other. Ball bearings tend to have lower load capacity for their size than other kinds of rolling-element bearings due to the smaller contact area between the balls and races. However, they can tolerate some misalignment of the inner and outer races. Common ball bearing designs include ''angular contact, axial, deep-groove,'' a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has a great affinity towards oxygen, passivation (chemistry), forming a protective layer of aluminium oxide, oxide on the surface when exposed to air. It visually resembles silver, both in its color and in its great ability to reflect light. It is soft, magnetism, nonmagnetic, and ductility, ductile. It has one stable isotope, 27Al, which is highly abundant, making aluminium the abundance of the chemical elements, 12th-most abundant element in the universe. The radioactive decay, radioactivity of aluminium-26, 26Al leads to it being used in radiometric dating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
