Analysis and prevention strategies for premature failure of gear and bearing grease in RX107-YB18.5-3.07 reducer

RX107-YB18.5-3.07 is a hard tooth surface helical gear reducer, suitable for 18.5KW motor, transmission ratio 3.07. The gears and bearings adopt a closed lubrication method. In most cases, gear oil is relied upon to achieve overall lubrication. In a few structures, the bearings are separately lubricated with grease. Premature failure of lubricating media is usually not caused by a single cause, but is the result of improper maintenance, inaccurate control of oil level or grease quantity, intrusion of external contamination, excessive operating temperature, irregular oil change intervals and other factors.

To fundamentally avoid premature failure of grease or gear oil, system control measures must be established in terms of lubricating media, filling specifications, temperature control, sealing protection, oil quality monitoring, oil change intervals, and basic maintenance.

1. Accurately select the lubricating medium to prevent failure from the source.

Wrong lubricating medium Selection is the core prerequisite for premature failure of RX107-YB18.5-3.07 reducer gear and bearing lubrication. If the oil or grease does not match the working conditions, even if subsequent maintenance is in place, it will be difficult to avoid problems such as lubricating film damage, oil oxidation, and lipid carbonization.

1. Gear lubricating medium Selection

For the gear part, priority should be given to medium-load industrial closed gear oil suitable for the working conditions of hardened helical gears:

• Normal temperature conditions : L-CKC 320# gear oil is preferred ;

• High temperature working conditions : When the ambient temperature is ≥35℃ or continuous operation under heavy load, L-CKC 460# should be selected.；

• Low temperature working conditions : When the ambient temperature is ≤5℃, L-CKC 220# can be used instead to ensure low temperature fluidity;

• Wet and dusty working conditions : gear oil with better water resistance and corrosion resistance should be selected;

• Impact load conditions : It is advisable to use extreme pressure and anti-wear gear oil containing sulfur and phosphorus additives to prevent the tooth surface lubricating film from rupturing under impact load.

It is strictly prohibited to use hydraulic oil or ordinary engine oil as a substitute for gear oil. It is not recommended to mix oils of different brands and the same grade to avoid performance degradation caused by inconsistent additive systems.

2. Bearing grease Selection

If the bearing adopts separate grease injection method, lithium-based extreme pressure grease should be used, such as LGMT 3# , whose dropping point should be ≥180°C, and the cone penetration should be controlled within the range of 220-250 to meet the lubrication needs of the reducer bearings under higher temperatures and heavy load conditions.

If the bearing and gear share gear oil lubrication, there is no need to add separate grease. Just ensure that the gear oil can fully cover the bearing raceway.

2. Strictly control lubricating medium filling specifications to prevent human failure

During on-site maintenance, many lubrication failures are not due to the quality of the oil itself, but to human failures caused by improper control of oil level, grease volume, and cleanliness.

1. Strictly control oil level and grease quantity

• Gear oil level : should be controlled at the middle position between the upper and lower limits of the oil level gauge.
  If the oil level is lower than the lower limit, it will cause insufficient lubrication of the gears and bearings; if the oil level is higher than the upper limit, it will intensify the mixing and heating of the oil, causing the oil temperature to rise and oxidation to accelerate.

• Bearing grease injection amount : If grease is injected alone, it is generally controlled at 1/2-2/3 of the bearing inner cavity volume. 。
  Too little grease injection can easily cause dry friction; too much grease injection will cause heat accumulation in the bearing cavity, leading to grease deterioration.

2. Cleaning must be done before filling

Before filling oil or grease, the oil filling port, oil gun, funnel and other tools should be wiped clean to prevent dust, iron filings and debris from entering the inside of the reducer. New oil should be filtered before filling, and the filter accuracy is recommended to be no less than 100 mesh to prevent impurities from scratching the gear tooth surface and bearing raceway, and to reduce the damage of impurities to the physical and chemical properties of the lubricating medium.

3. Mixing and cross-contamination are strictly prohibited

It is strictly forbidden to mix gear oils or greases of different types and brands. After mixing, problems such as stratification, flocculation, and abnormal viscosity may occur, destroying the original performance of the lubricating medium.

When replacing the lubricating medium, the old oil and grease remaining in the box must be cleaned up. If the old oil is not drained out, the new oil will be quickly contaminated after being added, causing the new oil to fail prematurely.

3. Strictly control the operating temperature to avoid high temperature acceleration of lubrication failure

Temperature is a key factor affecting the life of lubricating media. When the RX107-YB18.5-3.07 reducer is operating under rated working conditions, focus should be placed on controlling the oil temperature.

1. Clarify the normal oil temperature range

• Normal operating oil temperature should be controlled at ≤80℃；

• The maximum oil temperature in a short period of time should not exceed 90℃；

• If the oil temperature exceeds 90°C for a long time, it will significantly accelerate the oxidation of the gear oil and the carbonization of the grease, causing the lubrication performance to decline rapidly.

2. Do a good job in heat dissipation management and control

The heat sink of the reducer housing should be cleaned regularly to prevent dust and oil from clogging it and affecting heat dissipation. When the ambient temperature is relatively high, such as 40°C or above, a cooling fan or cooling device can be installed according to site conditions.

At the same time, long-term overload operation of the reducer should be avoided. Overload will aggravate the friction and heat generated during gear meshing and bearing operation, causing the oil temperature to rise rapidly.

3. Investigate the source of abnormal high temperature

If the oil temperature continues to exceed 90°C, it cannot be solved by changing the oil alone, but should be checked in order:

• Whether the oil level is too high;

• Whether the oil quality has deteriorated;

• Is the gear meshing normal?

• Whether the bearing is damaged;

• Is there any coaxiality deviation between the motor and reducer, reducer and load?

If the mechanical fault is not eliminated, high temperature and lubrication failure will still occur even if high-quality new oil is replaced.

4. Ensure sealing protection to prevent failure caused by external contamination

The failure of lubricating media not only comes from internal high temperature and oxidation, but is also closely related to the intrusion of dust, moisture, and impurities from the outside.

1. Maintain seal integrity

Shaft end oil seals, box joint surface seals and other parts should be checked regularly. When the oil seal is found to be aging, damaged, leaking or the sealing gasket fails, it should be replaced in time. When the oil seal lip is worn and the oil return spring fails, it should be replaced simultaneously to prevent dust, water vapor and impurities from entering the box.

2. Strengthen external environmental protection

The reducer installed in the open air should be equipped with a rainproof and dustproof cover to prevent rainwater and moisture from entering the box and causing oil emulsification. Under working conditions with a lot of dust, dust caps should be installed on the oil filling port and oil drain port, and their sealing status should be checked regularly.

3. Be wary of internal contamination

If metal debris, floc or obvious turbidity is found in the oil during operation, the machine should be stopped immediately to check for gear wear, bearing peeling and other internal faults. If the fault is not dealt with, even if new oil is replaced, it will soon be contaminated again.

At the same time, the water accumulated at the bottom of the tank should be drained regularly through the bottom of the oil drain port to prevent long-term accumulation of water from causing oil emulsification.

5. Standardize oil change intervals, monitor oil quality, and avoid extended use.

Improper management of oil change intervals is a common cause of premature failure of lubricating media. Factors such as new machine running-in, heavy-load operation, humid environment, etc. will affect the actual oil change interval.

1. Clarify the standard oil change interval

• New machine running-in period : the oil must be changed when During the running-in stage, gears and bearings will produce certain metal particles, which, if not replaced in time, will continue to contaminate the lubricating oil. the first operation reaches 500 hours .

• Normal operation stage : Generally, it should be replaced every 4000-6000 hours of operation , or at least once a year, whichever comes first.

2. Shorten the oil change interval according to working conditions

Under severe working conditions such as high temperature, heavy load, shock load, humidity and dust, the oil change cycle should be shortened by 30%-50%, that is, controlled to 2500-4000 hours . Frequent starts and stops and low-temperature start-stop conditions will also aggravate the performance degradation of the lubricating medium, and the oil change cycle should also be appropriately shortened.

3. Establish an oil quality monitoring mechanism

You should not only rely on regular oil changes, but also judge the oil quality condition.

• The color of the oil can be observed through the oil level gauge every month. If it is clear and transparent, it is normal. If it turns black or dark, you need to be alert;

• Oil samples can be taken for testing every 3 months;

• When the oil viscosity changes by more than 15%, the acid value exceeds the standard, or the water content exceeds 0.1%, the oil should be changed immediately.

6. Carry out basic maintenance of the reducer and avoid lubrication failure from the working condition level

Lubrication failure is often not only a lubrication management problem, but also closely related to installation accuracy, operating conditions and internal mechanical status.

1. Ensure installation accuracy

The coaxiality deviation between the motor and reducer, reducer and load should be controlled at ≤0.05mm , and the angular deviation should be controlled at ≤0.1° . Installation misalignment will aggravate the gear impact and bearing load, making the local lubricating film easily damaged, thereby accelerating the failure of the lubricating medium.

Anchor bolts should be tightened reliably to avoid excessive operating vibrations that may cause grease to fall off, oil to emulsify or seal to fail.

2. Strictly control operating conditions

Long-term overload operation should be avoided, and the load should generally not exceed 110% of the rated value. At the same time, impact operations such as frequent starts and stops, rapid acceleration, and rapid deceleration should be reduced. Such working conditions will cause gears and bearings to withstand large impacts in a short period of time, and the lubricating film will be easily destroyed, aggravating wear and contaminating the lubricating medium.

3. Regularly troubleshoot internal faults

It is recommended to shut down the machine every 6 months to check the gear meshing clearance and bearing clearance. If the gear meshing clearance is too large or the bearing clearance exceeds the standard, the impact friction will be aggravated and the lubricating medium will deteriorate rapidly.

When problems such as pitting corrosion on the tooth surface and slight wear on the bearing raceway are found, they should be dealt with in time to avoid further contamination of the lubricating medium after the fault expands.

7. Key points to avoid pitfalls and eliminate hidden failures

During on-site maintenance, some seemingly simple operational errors often become hidden causes of premature failure of lubricating media.

1. It is strictly forbidden to use grease instead of gear oil

Some maintenance personnel add grease to the gear parts for convenience. This approach is not advisable. During the gear meshing process, grease is easily squeezed out of the tooth surface, resulting in insufficient lubrication. At the same time, it will also be carbonized due to heat accumulation, affecting the normal operation of the gears and bearings. For RX107-YB18.5-3.07 reducer gear lubrication, the corresponding grade of gear oil should be used as required.

2. After filling with new oil, it should be run-in without load.

After replacing the new oil, it should be run without load for 10-15 minutes so that the oil can fully cover the gear tooth surface and bearing raceway to form a uniform lubricating film. If it is operated directly with load, local insufficient lubrication may occur, increasing the risk of tooth surface and bearing wear.

3. Waste grease should be disposed of in a standardized manner

The replaced old oil and grease are hazardous wastes and should be collected and stored centrally and handed over to professional organizations for processing. Standardized disposal can not only meet environmental protection requirements, but also prevent waste oil from contaminating the new oil storage environment and reduce subsequent maintenance risks.