The upper turntable of rotary device is one of the three parts of hydraulic excavator. In addition to the engine, hydraulic system, cab, counterweight, oil tank, etc., there is also a very important part in the rotary table - rotary device.

　　液压挖掘机回转装置由回转台、回转支承和回转机构组成。旋转装置的外阀座环通过螺栓与转盘连接，内带齿的阀座环通过螺栓与底部框架连接，内、外圈之间有滚动体。挖掘机工作装置作用于转盘上的垂直载荷、水平载荷和倾覆力矩通过旋转支承的外座环、滚动体和内座传递到底架上。旋转机构的壳体固定在转盘上，其小齿轮与旋转支架内座环上的齿环相啮合。

　　The slewing device of hydraulic excavator is composed of slewing table, slewing bearing and slewing mechanism. The outer valve seat ring of the rotating device is connected with the rotary table by bolts, the inner toothed valve seat ring is connected with the bottom frame by bolts, and there is a rolling body between the inner and outer rings. The vertical load, horizontal load and overturning moment of the working device of the excavator act on the turntable are transmitted to the base frame through the outer seat ring, rolling body and inner seat of the rotary support. The shell of the rotating mechanism is fixed on the rotary table, and its pinion gear is meshed with the tooth ring on the seat ring in the rotating support.

　　液压挖掘机的回转装置必须能够支撑转台的固定部分。不要翻车，要使转弯轻而灵活。因此，液压挖掘机设有回转支承装置(支承)和回转传动装置(带动转盘转向回转)，统称液压挖掘机回转装置。

　　The slewing device of the hydraulic excavator must be able to support the fixed part of the turntable. Don't roll over. Make the turn light and flexible. Therefore, the hydraulic excavator is equipped with a slewing bearing device (support) and a slewing transmission device (driving the rotary table to turn), which are collectively referred to as the slewing device of the hydraulic excavator.

　　回转支承的主要结构形式

　　Main structure of slewing bearing

　　1. 由摆动液压马达驱动的旋转立柱支架如图3-2所示。它由固定在旋转体1上的上下支承轴4和6，以及上下支承轴3和7组成。轴承座用螺栓固定在框架5上。旋转体与支承轴构成旋转柱，旋转柱插入轴承座的轴承内。壳体固定在机架5上的摆动式液压缸输出轴上，插入下支撑轴6，带动旋转体相对于机架旋转。“匚”形式的转子经常让它,为了避免碰撞与回转机构。工作装置铰接在旋转体上，并随旋转体旋转。

　　1. The rotating column bracket driven by the swing hydraulic motor is shown in Figure 3-2. It consists of upper and lower supporting shafts 4 and 6 fixed on the rotating body 1, and upper and lower supporting shafts 3 and 7. The bearing pedestal is bolted to frame 5. The rotating body and the supporting shaft form a rotating column which is inserted into the bearing of the bearing seat. The shell is fixed on the output shaft of the swinging hydraulic cylinder on the frame 5, and the lower support shaft 6 is inserted to drive the rotating body to rotate relative to the frame. The "zhe" type of rotor often lets it, in order to avoid collision with the slewing mechanism. The working device is hinged on the rotating body and rotates with the rotating body.

　　2. 滚动轴承回转轴承实际上是一种大直径滚动轴承。它与普通轴承的区别是它的速度很慢。挖掘机的转速范围为5~11r/min。此外，一般轴承的滚道直径与高度之比为4~5，而回转轴承可达10~15。因此，该轴承的刚度较差，工作时应依靠支撑连接结构来保证。

　　2. The rolling bearing is actually a large diameter rolling bearing. The biggest difference between it and ordinary bearing is its slow speed. The speed range of excavator is 5 ~ 11R / min. In addition, the ratio of the center diameter to the height of the raceway of the general bearing is 4-5, while that of the rotary bearing is 10-15. Therefore, the stiffness of the bearing is poor, and the support connection structure should be relied on to ensure the work.

　　典型的滚动轴承式回转轴承结构。内环或外圈可加工成内环或外圈。带有齿轮环的阀座环是一种固定环，用螺栓4和5沿圆周分布固定在底座上。无齿座环为旋转环，通过螺栓与挖掘机转台连接。装配时，先将阀座环1、3和滚动体8安装成一个完整的部件，然后与挖掘机装配。为保证转动灵活，防止热膨胀后卡死现象，回转环应留有一定的轴向间隙。由于加工误差和滚道和滚体的磨损，间隙会发生变化。因此，在两个环之间有一个调整垫圈2，以调整装配和修理期间的间隙。

　　Typical rolling bearing type slewing bearing structure. The inner ring or outer ring can be processed into the inner ring or outer ring. The seat ring with gear ring is a fixed ring, which is fixed on the base with bolts 4 and 5 along the circumference. The toothless seat ring is a rotating ring, which is connected with the turntable of the excavator through bolts. When assembling, first install the seat rings 1, 3 and the rolling elements 8 into a complete part, and then assemble with the excavator. In order to ensure the flexibility of rotation and prevent the seizure after thermal expansion, a certain axial clearance should be reserved for the rotating ring. Due to machining error and wear of raceway and roller body, clearance will change. Therefore, there is an adjusting washer 2 between the two rings in order to adjust the clearance during assembly and repair.

　　隔离体7是用来防止相邻的滚压体8的挤压，减少滚压体的磨损，起到导向作用。卷轴可以是一个球或滚轴。滚动轴承式回转支承机构广泛应用于全回转液压挖掘机中。它是在普通滚动轴承的基础上发展起来的，相当于结构上的扩大滚动轴承。它与传统的滚动轴承相比,具有体积小,结构紧凑,承载能力大,旋转摩擦阻力小,小辊之间的差距和跟踪,维护方便,使用寿命长,容易实现三个特点的一系列优势,这是与普通滚动轴承相比,及其特点:普通滚动轴承的内圈与外圈之间的刚度依靠轴与轴承总成之间的刚度来保证，同时有转盘和底盘来保证;回转支承的转速较低，通常承受轴向载荷，因此轨迹上接触点的周数较少。

　　The separator 7 is used to prevent the extrusion of the adjacent rolling body 8, reduce the wear of the rolling body and play a guiding role. The reel can be a ball or a roller. The rolling bearing type slewing bearing mechanism is widely used in the full rotation hydraulic excavator. It is developed on the basis of common rolling bearing, which is equivalent to expanding rolling bearing in structure. Compared with the traditional rolling bearing, it has a series of advantages, such as small volume, compact structure, large bearing capacity, small rotating friction resistance, gap and tracking between small rolls, convenient maintenance, long service life, and easy to realize three characteristics. This is compared with the ordinary rolling bearing, Its characteristics: the rigidity between inner ring and outer ring of common rolling bearing depends on the rigidity between shaft and bearing assembly, and is guaranteed by turntable and chassis at the same time; the rotation speed of slewing bearing is low, usually bearing axial load, so the number of contact points on the track is less.