Considering its colourable and castable nature, its extended hardness range, low wear and superior load bearing capacity, polyurethane is a smart substitute for rubber.
During the period when stor-age de velops towards networking,the factors of the scale,maturity and comparatively low cost of Eth-ernet must be taken into con sideration.
The position of bearing point is got according to the equal angle of rotation between purlin and Queti,thus its maximum internal force can be obtained.