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Preliminary Analysis of Notes on Debugging of Excavator Slewing Bearings

06-16, 2022 / in Bearing Knowledge / by LDB

We all know that when the excavator is working, it can twist left and right, front and rear mainly by the slewing mechanism in the machine, and the slewing bearing plays a vital role as an important part of the slewing mechanism. When assembling and overhauling and using and maintaining the excavator slewing bearing, the debugging of the slewing mechanism will be carried out, and the tightness of the assembly structure of the excavator slewing bearing requires us to master the correct operation method to avoid misadjustment. So what are the precautions for the debugging of the excavator slewing bearing?

The debugging of the excavator slewing bearing generally refers to the debugging of the backlash between the output gear of the slewing reducer and the ring gear of the slewing bearing. The proper adjustment of the inter-gear yard not only ensures that the pinion gear and the large gear do not gnaw and cut each other, but also ensures that the excavator rotates and brakes smoothly. Under normal circumstances, the eccentric distance between the center of the pinion and the installation and positioning center of the rotary reducer is used, and the center distance between the pinion and the large gear is changed by rotating the rotary reducer, thereby changing the tooth side clearance of the gnawing gear to debug the rotary mechanism.

excavator slewing bearing

Since the sway of the excavator's slewing brake is caused by the slewing reducer, the operator often mistakenly thinks it is caused by too large backlash, so he tries to adjust the backlash by rotating the slewing reducer. After the rotary reducer rotated a screw hole position, it was found that the debugging results were not satisfactory, and then another screw hole position was rotated.

1. Before debugging the slewing bearing mechanism of the excavator, it is necessary to identify the gear teeth with large radial full runout of the pitch circle of the gear on the large gear and the direction of the midpoint of the pinion of the slewing reducer.

2. The slewing mechanism can only be debugged when the gear teeth on the pinion and the gear pitch circle on the big gear with full beating in the radial direction are engaged, that is, the slewing reducer can be rotated. There will be no interference between the gear and the big gear, and the big gear cannot be gnawed.

3. When debugging is required, in most cases, the rotary reducer only needs to rotate one screw hole position, and in rare cases, two screw holes need to be rotated, which is basically the same as the actual situation of our factory debugging the rotary mechanism for many years. Therefore, after the rotary reducer rotates one screw hole position, if the sway of the excavator still does not improve significantly during the slewing braking, do not blindly rotate the rotary reducer to the second screw hole position, but first find the reason.

4. When adjusting the gear gap, pay attention to observe whether the connecting bolts between the rotary motor reducer and the rotary platform are loose, so as to avoid the gear meshing gap being too large or too small. This is because if the gap is too large, it will cause a large impact force on the gear when the excavator starts and stops, and it is prone to abnormal noise; if the gap is too small, it will cause the slewing bearing and the slewing motor reducer pinion to get stuck, even lead to broken teeth.

excavator slewing bearing

5. According to the gear transmission characteristics between the pinion and the large gear of the slewing bearing mechanism of the excavator, the side clearance should be guaranteed to be a medium value, especially the small side clearance should not be too small.

6. Accurately grasp the clearance adjustment and preload limit. Clearance refers to the maximum amount of movement of the other ferrule in the radial or axial direction when one ferrule is fixed, so the clearance is divided into radial play. clearance and axial clearance. If the clearance is too large, the number of rolling elements that bear the load at the same time will decrease, which will increase the load of a single rolling element, thereby reducing the rotation accuracy of the bearing and reducing the service life; if the clearance is too small, the friction force will increase, resulting in The increase of heat and wear will also reduce the service life of the bearing.

The adjustment and preload of the clearance are usually done by making the inner ring of the bearing make an appropriate axial relative displacement to the outer ring. The preload can improve the rigidity and rotation accuracy of the bearing under working conditions.

The above is a brief introduction to the precautions for debugging the slewing bearing of the excavator. From the actual investigation and understanding, we know that when the slewing reducer is rotated during the debugging process, the radial full runout of the pitch circle of the large gear engaged with the pinion is just small, and the two The gears can be meshed normally, but it is known from the above analysis that at this time, there is little or no interference between the gears of the gears. Therefore, when the slewing brake inspection is carried out after commissioning, the total radial runout between the pinion and the pitch circle of the gear is large. The teeth of the large gear interfere with each other, and as a result, the large gear is cut by the pinion. The larger the gear pitch circle radial runout is, the more serious the gnawing phenomenon is, which is completely consistent with the actual observation results.

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