Slewing Bearing

A slewing bearing or slew[ing] ring is a rotational rolling-element bearing that typically supports a heavy but slow-turning or slow-oscillating load, often a horizontal platform such as a conventional crane, a swing yarder, or the wind-facing platform of a horizontal-axis windmill. (To "slew" means to turn without change of place.) Compared to other rolling-element bearings, slewing bearings are thin in section and are often made in diameters of a metre or more; the slewing bearings on the Falkirk Wheel are 4 metres diameter and fit over a 3.5 metre axle. Slewing bearings often use two rows of rolling elements. They often use three race elements, such as an inner ring and two outer ring "halves" that clamp together axially. Slewing bearings are often made with gear teeth integral with the inner or outer race, used to drive the platform relative to the base. As for other bearings that reciprocate, rather than rotating continuously, lubrication can be difficult. The oil wedge built up in a continuously rotating bearing is disrupted by the stop start motion of slewing. Instead, a hydrostatic bearing with pumped oil flow may be used. Slewing bearing is nearly forty years worldwide emerging new type of mechanical parts, it is composed of inner and outer ring, rolling body, etc, finalize the design production of slewing bearing in China, mainly in the early 80 s by the ministry of machinery industry in tianjin institute of engineering machinery group introduced the former federal republic of Germany Rothe Erde design and manufacturing technology of the company.Released on December 20, 1984 of the People's Republic of China machinery industry standard: JB / 2300-84 the rotary bearing type, basic parameters and technical requirements, composed mainly of machinery and electronics industry of tianjin engineering machinery research institute, xuzhou hering slewing bearing factory is responsible for drafting, the country then issued standard of construction machinery in 1991: JB36.1-36.3-91, released in 1999 and 2011 successively new machinery industry standard JB / 2300-1999 and JB / 2300-2011. Slewing bearing, is a kind of comprehensive load to bear a large bearings, can withstand the larger axial and radial load and tilting moment.Slewing ring bearings generally installed with a hole in the gears or gear, grease holes and sealing device, which enable mainframe design compact structure, and guide is simple, easy to maintain.Slewing bearing presence of tooth, tooth and tooth in the four-point contact ball bearing, double row angular contact ball bearing, crossed cylindrical roller bearing, crossed tapered roller bearing and three composite bearings, four row cylindrical roller series, including four-point contact ball bearing has high static load capacity, crossed cylindrical roller with high load capacity, preloaded can make crossed tapered roller bearing bearing has great support stiffness and the rotation accuracy, three rows of cylindrical roller bearing combination height because of the increase to the bearing capacity of bearing, all kinds of power respectively by different race to bear, so under the same stress distribution, the bearing diameter can be significantly reduced, thus make the characteristics of the host more compact is a kind of high bearing capacity of slewing ring bearings.Slewing bearings are widely used in hoisting machinery, mining machinery, construction machinery, port machinery, ship machinery and mechanical precision radar and missile launcher equipment such as large rotary device.At the same time also can according to customer's specific requirements of the design, development, production various special slewing bearing structure.