What are the main failure modes of closed soft-tooth surface gears?

[SanAlaina]

The main failure modes of closed soft-tooth surface gears are as follows: 1. Tooth breakage: Tooth breakage usually occurs in two situations: one is fatigue breakage caused by repeated bending stress and stress concentration; the other is overload breakage caused by sudden severe overload or impact load. 2. Pitting: During gear operation, under the repeated action of alternating contact stress at the meshing point, small cracks will appear on the tooth surface near the pitch line. As the cracks expand, small pieces of metal will peel off, a phenomenon called pitting. Continued expansion of pitting will affect the smoothness of transmission, generate vibration and noise, and prevent the gear from working properly. 3. Tooth surface wear: During gear meshing, due to relative sliding, especially when external hard particles enter the meshing working surface, tooth surface wear will occur. After gradual wear, the tooth surface will lose its correct shape, and in severe cases, the tooth will become too thin and break. Tooth surface wear is the main failure mode of open gear transmissions. To reduce wear, important gear transmissions should use closed transmissions and pay attention to lubrication. 4. Tooth surface scuffing: In high-speed and heavy-duty gear transmissions, the pressure between tooth surfaces is high, the temperature rises, and the lubrication effect is poor. When the instantaneous temperature is too high, the two tooth surfaces will partially melt and adhere to each other. When the two tooth surfaces move relative to each other, the adhered parts will tear, forming banded or large-area scars along the sliding direction on the tooth surface. Low-speed and heavy-duty transmissions are not easy to form an oil film. Although the friction heat is not high, cold scuffing may still occur due to heavy loads. 5. Tooth surface plastic deformation: For soft-tooth surface gears with low hardness, under low-speed and heavy-duty conditions, the excessive tooth surface pressure and friction will cause the metal on the tooth surface to undergo plastic flow and lose its original shape. Increasing tooth surface hardness and using higher-viscosity lubricating oil can help prevent or reduce tooth surface plastic deformation.

[DelHarmony]

When I used to drive older model cars, the most common issue with enclosed soft-tooth-surface gears was the appearance of small pits on the surface, commonly known as pitting. This mainly occurs due to surface material fatigue when the gears rotate at high speeds, leading to gradual flaking and the formation of pits. Additionally, there's wear—over time, the tooth surfaces thin out due to friction, affecting transmission efficiency. Sometimes, teeth can even break, like snapping suddenly under overload. These problems are particularly prone to occur in enclosed gearboxes because of high heat and inadequate lubrication. I recommend changing the gear oil regularly and checking for signs of wear; otherwise, the car may experience difficulty starting or shifting gears. Overall, pitting ranks first, followed by other wear and tooth breakage, requiring early prevention to ensure long-term use.

[MakaylaRose]

Having worked in the mechanical industry for years, I've repaired numerous enclosed soft-tooth-surface gearboxes, which are prone to various common issues. Pitting is the primary failure mode, manifesting as pockmarks on the tooth surface; followed by wear, where material gradually erodes and becomes rough; then there's fracture, caused by stress concentration leading to tooth breakage. There's also the problem of scuffing, where surfaces adhere when lubrication fails. Why are soft-tooth surfaces susceptible to these issues? Because the material has low hardness and is prone to deformation under pressure. I recommend regular checks of oil temperature and pressure, and timely replacement of worn parts. Keeping these in mind can help reduce unexpected downtime losses.

[HarperFitz]

As a novice driver just learning, I've found that closed soft-tooth-surface gears are most afraid of fatigue issues. Pitting and wear are the most common, with small pits or rough surfaces; fractures also occur occasionally. There are various causes of failure, such as prolonged operation, excessive load, or oil degradation. My experience is to listen for unusual noises before driving and pay attention to smooth gear shifting. Once failure occurs, repair it immediately to prevent further damage. Simply put, fatigue pitting is the main issue, followed by wear.