Why castor wheel specifications are expressed in inches
In the design, development and production of caster swivel wheel, the metric system, the United States system and British system units are unavoidable problems, these are the system of measurement units. At present, the system of measurement units used in the world mainly includes the following: atomic system of units, Taiwan system, international system of units, Planck system of units, natural system of units, British system of units and our Chinese folk use of the municipal system, etc.
First, let’s talk about international units. The International unit, also known as the metric system or the metric system, is familiar to all of us here, but I’ll just give you a brief explanation. The metric system, formerly known as the “metric system of nations,” is now the world’s most widely used standard system of measures. The International system of units originated from the efforts of scientists in the late 18th century, and was first adopted as a unit of measurement in France in 1799 during the French Revolution. It is called the metre process, or meter, based on the length of the Earth’s meridian as a standard, and 40 millionths of the length of the meridian through Paris as a unit of length; To one thousandth of a cubic meter as a unit of capacity, named litre; The mass of a liter of pure water at 4°c is taken as the mass unit and named as kilogram. In 1875, 17 European and American countries set up the International Bureau of Measurement in Paris, which specialized in manufacturing and preserving platinum-iridium alloy original devices as the international standard of length and quality.
At present, the SI system of units is used all over the world because the decimal system is easy to use. Officially, the International system of units is the main system of weights and measures in all countries except the United States, Myanmar and Liberia, which do not mainly use the SI system. These include the vast majority of the former British system countries, such as the UK, Canada, Australia, etc., all of which converted to the SI system in the second half of the 20th century. However, in the aviation control system, the British system is still used internationally (for example, the flight altitude will be in feet).
In 1928, the government of the republic of china promulgated the law of weights and measures, which provided for the adoption of the “universal metric system” as the standard system, and temporarily established the auxiliary “market system” as a transition, i.e., 1 meter is 3 city feet, 1 liter is 1 city liter, and 1 kilogram is 2 city jin. After the reform, the municipal system adapted to the habits of the public and was easily converted to the metric system, which was gradually accepted by the public. After 1949, the municipal system was adopted throughout the country. In 1984, The State Council issued an order to adopt the legal units of measurement of the People’s Republic of China (hereinafter referred to as legal units) based on the international system of units (SI) while selecting some non-SI units. Since January 1, 1991, the legal unit has become the only legal unit of measurement in China.
Why are casters often described in inches? To discuss the cause of the castor specifications in terms of inches, have to talk about the development history of castor, though, we know China early design and use of castor wheels, but the casters & wheels the definition of the word as a castor and wheels and batch production and sales, is due to after the reform and development, at a time when China is mainly the OEM manufacturer, The bulk export countries are the United States and other countries that use British units. The specifications of casters are customized according to customer requirements, so it is logical that the specifications of casters are often expressed by “inch”.