中文字幕乱码免费视频,日本三级欧美三级人妇视频黑白配,另类内射国产在线,久久久久国色AV免费观看性色

News   
    Contact Us   
    Search   
    Your Position: Home > News

    Bearing origin

    2016/11/27      view:
    China is one of the countries in the world earlier invention of rolling bearings, in ancient China, the structure has long been documented on the axle bearings. And data from archaeological perspective, China's oldest modern rolling bearing structure bearing the prototype, and appeared in 221 BC - 207 BC(Qin) is now Shanxi Yongji County the Xue's Cliff Village. After the founding of New China, especially since the seventies of thelast century, under thestrong promotion of reform and opening up, the bearing industry has entered a new period of rapid development of high quality.

    In the seventeenth century, the British design and manufacturing ballbearings C. Vallo, and installed in the car to try and British postal P.Wirth made ball bearings patent. Eighteenth century German publication on ball bearings HR Hertz contact stress papers. Onthe basis of the achievements of the Hertz, R. Striebeck Germany, Sweden,Glenn A. Pam, who have done a lot of testing, the design theory and the development of fatigue life of rolling bearings is calculated to make acontribution. Subsequently, the Russian Petrov NP Newton's law to calculate the viscous friction bearings. British Thor O. Renault were found mathematical analysis, Reynolds equation is derived, from the foundation hydrodynamic lubricationtheory.

    The early form of linear motion bearings, placed in a row is a row of wooden skid plate under. This technique might be traced back to the time of the construction of the Great Pyramid of Giza, although there is no clear evidence. Modern linear motion bearings using the same kind of works, but sometimes with the ball instead of rollers. The first sliding and rolling element bearings are made of wood. Ceramic,sapphire or glass are also used, steel, copper, other metals, plastics(such as nylon, bakelite, Teflon and UHMWPE) have been widely used.



    三上悠亚公侵犯344在线观看| 国产午夜无码片在线观看网站| 天堂中文最新版在线官网在线| 国产性色AV免费观看| 无码高潮少妇多水多毛| А√天堂中文官网在线|