Nmrv 130 Gearbox

The nmrv 130 gearbox achieves precise speed and torque control by adjusting the transmission ratio. It features high efficiency, smooth operation, compact design, low noise and strong durability. It is applicable to various fields and provides flexible and reliable performance. It is widely applied in industries such as industry, mining and chemical engineering.

During the use of the nmrv 130 gearbox, many problems will be encountered, such as high noise and severe gear wear; Today, let's talk about the problem of oil leakage in reducers, such as severe heating, oil leakage, and decreased transmission accuracy.

There are several reasons for oil leakage in reducers

1.A pressure difference is generated between the inside and outside of the reducer

2. The structural design of the reducer is unreasonable

1) The inspection hole cover plate is too thin. After tightening the bolts, it is prone to deformation, causing the joint surface to be uneven and oil leakage from the contact gap.

2) During the manufacturing process of the reducer, if the castings are not subjected to annealing or aging treatment and the internal stress is not eliminated, deformation is bound to occur, resulting in gaps and leakage.

3) There is no oil return groove on the box body. Lubricating oil accumulates at the shaft seal, end cover, mating surface, etc. Under the action of pressure difference, it leaks out from the gap.

4) The shaft seal structure design is unreasonable. Early reducers mostly adopted oil groove and felt ring type shaft seal structures. During assembly, the felt was compressed and deformed, thereby sealing the gaps at the mating surfaces. If the contact between the journal and the seal is not very ideal, due to the extremely poor compensation performance of the felt, the seal will fail in a short time. Although there are return oil holes on the oil gutter, they are prone to clogging and the return oil function is difficult to be exerted.

3.Excessive oiling: During the operation of the reducer, the oil pool is stirred vigorously, and the lubricating oil splashes everywhere inside the machine. If too much oiling is applied, a large amount of lubricating oil will accumulate at the shaft seal, joint surface, etc., causing leakage.

4. Improper maintenance techniques: During equipment maintenance, if the dirt on the joint surface is not thoroughly removed, or if the sealant is improperly selected, the sealing parts are installed in the wrong direction, or the sealing parts are not replaced in time, oil leakage may also occur.

Countermeasures for controlling oil leakage in reducers

1.Improve the ventilation cap and inspection hole cover plate: One of the main reasons for oil leakage is that the internal pressure of the reducer is greater than the external atmospheric pressure. If the pressure inside and outside the machine is balanced, oil leakage can be prevented. Although all reducers are equipped with vent caps, the vent holes are too small and are prone to being clogged by coal powder and oil stains. Moreover, every time oil is added, the inspection hole cover plate needs to be opened. Each opening increases the possibility of oil leakage, causing leakage in areas that were originally not leaking. For this purpose, an oil cup-type breathable cap was fabricated. The original thin inspection hole cover plate was changed to 6 mm thick, and the oil cup-type breathable cap was welded onto the cover plate. The diameter of the ventilation hole was 6 mm, which was convenient for ventilation and achieved pressure equalization. Moreover, when refueling, oil is added from the oil cup without opening the inspection hole cover plate, reducing the chance of oil leakage.

2. Smooth flow: To prevent the excess lubricating oil flung onto the bearing by the gear from accumulating at the shaft seal, it is necessary to ensure that the excess lubricating oil flows back to the oil pool in a certain direction, that is, to achieve smooth flow. The specific approach is to open a return oil groove inclined towards the interior of the machine at the center of the lower bearing housing. At the same time, a gap is also made at the straight opening of the end cover, with the gap directly facing the return oil groove. In this way, the excess lubricating oil flows back to the oil pool through the gap and the return oil groove.

3. Improve the shaft seal structure

1) Improvement of the shaft seal of the reducer with a half shaft output: The output shafts of most equipment such as belt conveyors, screw unloading machines, and impeller coal feeders are half shafts, making the transformation relatively convenient. Disassemble the reducer, remove the coupling, and take out the end cover of the reducer shaft seal. According to the size of the matching skeleton oil seal, machine a groove on the outside of the original end cover, install the skeleton oil seal, with the side with the spring facing inwards. When reinstalling, if the distance between the end cover and the inner end face of the coupling is more than 35mm, a spare oil seal can be installed on the shaft outside the end cover. Once the oil seal fails, the damaged oil seal can be removed and the spare oil seal pushed into the end cover, thus eliminating the time-consuming and laborious procedures such as disassembling the reducer and removing the coupling.

2) Improvement of the shaft seal for reducers with an integral output shaft: For reducers with integral shaft transmission, the output shaft has no coupling. If it is modified according to the scheme in 2.3.1, the workload would be too large and unrealistic. To reduce the workload and simplify the installation procedure, a separable end cover was designed, and an attempt was made on the open oil seal. The outer side of the detachable end cover is machined with a groove. When installing the oil seal, first remove the spring, saw the oil seal to form an open shape, and then put the oil seal on the shaft through the opening. Use adhesive to connect the opening with it facing upwards, then install the spring and push it into the end cover.

4. Adopt new sealing materials: For leakage at the static sealing points of the reducer, new high-molecular repair materials can be used for sealing and blocking. If there is oil leakage at the static sealing point of the reducer during operation, the oil surface emergency repair agent adhesive - high molecular 25551 and 90T composite repair material of surface engineering technology can be used to block it, thereby achieving the purpose of eliminating the oil leakage.

5. Strictly follow the maintenance procedures: During the maintenance of the reducer, the process regulations must be strictly followed. The oil seal must not be installed in reverse, the lip must not be damaged, the outer edge must not be deformed, the spring must not fall off, the mating surface must be cleaned thoroughly, the sealant must be applied evenly, and the oil filling quantity must not exceed the mark on the oil dipstick.

Wiping: After treatment, the static sealing points of the reducer can generally achieve no leakage. However, due to reasons such as aging of the sealing parts, poor quality, improper assembly, and high surface roughness of the shaft, there is still a slight leakage at the dynamic sealing points. Due to the poor working environment, coal dust adheres to the shaft, making it look oily. Therefore, after the equipment stops running, the oil stains on the shaft need to be wiped.

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