Common Damage Causes Of Gearbox Bearing

The one shaft bearing of the gearbox is to support the mechanical rotating body, reduce the friction coefficient in the process of movement, and ensure the precision of the gearbox.Manual transmission is mainly composed of gears and shafts, which generate variable speed and torque through different gear combinations.The following is an introduction to the cause of its damage

Gearbox structure
In order to better find out the causes of gearbox bearing damage, first of all, we need to understand the structure of the transmission gearbox. The main components of gear box include gear box, seal, bearing, gear, bearing seat, grounding device and suspender. The big gear is pressed on the axle, and the big gear bearing is connected with the gear box and the axle through the big gear bearing cover to ensure the relative rotation of the axle, the big gear and the gear box. The pinion shaft is installed in the gear box through the bearing and the bearing cover, and the pinion and the large gear mesh to transmit power. The gear box suspender is connected with the frame. The extended end of the pinion shaft is flexibly connected with the traction motor through the coupling, which transmits the power of the traction motor to the axle to drive the vehicle.
In order to reduce the mass under the spring, the gear box is made of cast aluminum alloy. 75w-90 series lubricating oil with viscosity grade is used for lubrication of gears and bearings. The splash lubrication mode driven by large gear rotation is adopted. The designed oil injection is 2.5L medium oil level. The bearings on the side of big gear and small gear are tapered roller bearings. The tapered roller bearing adopts face-to-face arrangement, which can meet the requirements of radial and axial loads. The assembly and disassembly are more convenient. The bearing clearance is controlled by adjusting the adjusting gasket between the bearing seat and the box.

Causes of gearbox bearing damage
According to the on-site inspection and disassembly inspection of the fault gearbox, it is judged that the failure process of the bearing in the gearbox is as follows: when the gearbox is used, there is sliding friction between the roller end face and the inner ring big rib; When the lubrication condition is not good, the possibility of oil film discontinuity is increased due to the insufficient lubrication between the big end face of roller and the big rib of inner ring, which easily leads to the burning failure of roller and the big rib of inner ring. According to the small shaft bearings on both sides, the small shaft damage and the operation force, the PW side bearing is seriously damaged. It is judged that the PW side bearing first fails in the process of failure, and then under the small shaft force, the other side bearing is damaged.
Based on the analysis of the test results, the following conclusions are drawn
The results show that:

(1) under the same temperature (≤ 30 ℃), the viscosity of the new lubricating oil is lower than that of the original lubricating oil, and the fluidity is better;
(2) under the same test conditions, the lubrication condition of small bearing of gearbox can be improved obviously by increasing the amount of lubricating oil;
(3) using the original lubricating oil for fault recurrence test, increasing the small bearing clearance can not avoid the small bearing burning, and the small bearing clearance is not the main factor leading to the small bearing burning.
The test results show that the new lubricating oil with better low-temperature performance can meet the requirements of normal operation in - 25 ℃ low-temperature environment without changing the gearbox parameters.The reason of small shaft side bearing burning is that the lubrication condition of small bearing is poor in low temperature environment, resulting in the short-term discontinuity and poor lubrication of lubricating oil film between the large end face of bearing roller and the large rib of inner ring, resulting in bearing burning damage.

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