Slewing Ring bearing has been developed as a new machine part in recent 30 years. It is first used in excavator and crane, and then applied to other machines. Slewing bearing is almost the same as oversize ball and roller bearing. Figure 1-1 shows double-row ball Slewing bearing''''''''s structure. Figure 1-2 shows how Slewing bearing is used in Caterpillar Crane. It connects the upper and lower parts of the machine, bearing the weight and working load of the upper part, and makes the upper slew relatively.
Slewing bearing is widely used in different industries. It is suitable for hoisting machine (truck crane, tower crane, etc.), construction machinery (excavator, loading and unloading machine), transporting machine, material processing machine, Metallurgy Machinery, food processing machine, military product (tank, s anti-aircraft gun, radar, missile launcher, etc.), medical instrument research equipment, etc.
Slewing bearing, like common bearing, has roller and rolling ring with raceway. But, compared with common roller bearing, it has many special features. They can be summarized in the following points:
The size of Double-Row Ball Slewing Bearing is great; its diameter is generally between 0.4m~10m, some even is up to 40m.
Slewing bearing usually bears load from different parts. It doesn''''''''t only bear the axial force, radial force, but also tipping moment simultaneously. Therefore, a set of Slewing bearing often completes the functions of many sets of common roller bearing.
The speed of Slewing bearing is fairly low, usually below 10 r/min. Moreover, on most occasions, Slewing bearing doesnĄ¯t slew continually, but only slew back and force in a certain angle like the so called Swing Bearing. Slewing bearing differs greatly from roller bearing in process techniques, material and heat treatment. Generally, Slewing bearing has gear ring as driving device and Seal Device to pretend dust. Unlike the common bearing fixed on the central pivot in the bearing box, Slewing bearing has big size and is attached to upper and lower plates by bolts.
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