How to choose between slewing external gear ring or slewing internal gear ring, and what are their advantages and disadvantages?

 1. Slewing internal gear ring: Due to the teeth inside the slewing bearing, the overall appearance of the inner toothed slewing bearing is relatively clean. The meshing of the driving gear and the slewing bearing is located inside the slewing bearing, and there is no need to install a safety protective cover. The gear has good dust resistance, and the lubricant is added for a longer retention time. Additionally, the transmission contact stress of the internal teeth meshing is low, with small wear and tear, and a longer service life. However, due to size limitations, the internal space of the internal toothed slewing bearing is relatively compact, making it relatively inconvenient for installation and debugging in the early stage, as well as for fault diagnosis and gear meshing inspection in the later stage.

2. Slewing external gear ring: The teeth of the external tooth type slewing bearing are located outside the slewing bearing, which is relatively convenient to install and can maximize the limited space of the slewing bearing. Fault diagnosis and gear meshing inspection are easy, and due to the large pitch diameter of the gear ring, it can better obtain a larger transmission ratio, greatly reducing the circumferential force and torque on the small gear.

Slewing internal gear ring support structure

Slewing internal gear ring mainly consists of a rolling element, an inner ring, and an outer gear ring, etc. The inner ring and outer gear ring are fixed to the rotary sleeve and shell by high-strength bolts, respectively. The installation bolts should comply with the standards of GB 3098.1 and GB 5782, and should not be lower than high-strength bolts of grade 8.8. Flat washers or nuts with double-sided anti loosening threads and hardened should be used to prevent loosening. The installation of bolts requires a certain pre tightening force, which should be 0.65-0.7 times the yield limit of the bolt. Check the pre tightening force of the bolts once after 100 hours of equipment operation, and then every 400 hours of operation thereafter. Add No. 2 extreme pressure lithium grease once every 100 hours of operation.

Slewing internal gear ring is a ball or roller type supporting slewing device developed on the basis of ordinary rolling bearings, structurally equivalent to an enlarged rolling bearing. Therefore, it is also known as a "large (or extra large) rolling bearing". Due to its many outstanding advantages, slewing bearings have been widely used in excavators, cranes, and other construction machinery in recent years.

Generally, the stiffness of the inner and outer rings of rolling bearings is ensured by the assembly of the shaft and bearing seat, while the stiffness of the slewing bearing is ensured by the chassis structure that supports it.

The rotational speed of the slewing external gear ring is low, and it usually bears axial load, radial load, and overturning torque. Therefore, the number of contact point load cycles on the raceway of the slewing bearing is relatively small. In design calculations, the main focus is on calculating the bearing capacity to determine the maximum contact stress between the rolling element and the raceway at the contact point.

Slewing internal gear ring is an indispensable transmission device in the excavator slewing system. Users who have used the slewing bearing should be aware that after a period of use of the bearing, there will be certain wear and loss. 

The main reasons for the wear of the excavator Slewing internal gear ring are:

1. When purchasing a slewing bearing, the model matching is incorrect. When docking the tooling, there may be speed mismatch and excessive load, resulting in wear of the inner and outer teeth;

2. Improper selection of the design and material selection of the slewing bearing for the tooling model can lead to accelerated wear of the Slewing internal gear ring.

Slewing Innernal Gear Ring supplier