1、齿面磨损

对于开式齿轮传动或含有不清洁的润滑油的闭式齿轮传动，由于啮合齿面间的相对滑动，使一些较硬的磨粒进入了摩擦表面，从而使齿廓改变，侧隙加大，以至于齿轮过度减薄导致齿断。一般情况下，只有在润滑油中夹杂磨粒时，才会在运行中引起齿面磨粒磨损。

2、齿面胶合

对于高速重载的齿轮传动中，因齿面间的摩擦力较大，相对速度大，致使啮合区温度过高，一旦润滑条件不良，齿面间的油膜便会消失，使得两轮齿的金属表面直接接触，从而发生相互粘结。当两齿面继续相对运动时，较硬的齿面将较软的齿面上的部分材料沿滑动方向撕下而形成沟纹。

3、疲劳点蚀

相互啮合的两轮齿接触时，齿面间的作用力和反作用力使两工作表面上产生接触应力，由于啮合点的位置是变化的，且齿轮做的是周期性的运动，所以接触应力是按脉动循环变化的。齿面长时间在这种交变接触应力作用下，在齿面的刀痕处会出现小的裂纹，随着时间的推移，这种裂纹逐渐在表层横向扩展，裂纹形成环状后，使轮齿的表面产生微小面积的剥落而形成一些疲劳浅坑。

4、轮齿折断

在运行工程中承受载荷的齿轮，如同悬臂梁，其根部受到脉冲的周期性应力超过齿轮材料的疲劳极限时，会在根部产生裂纹，并逐步扩展，当剩余部分无法承受传动载荷时就会发生断齿现象。齿轮由于工作中严重的冲击、偏载以及材质不均匀也可能引起断齿。

5、齿面塑性变形

在冲击载荷或重载下，齿面易产生局部的塑性变形，从而使渐开线齿廓的曲面发生变形。

1. Tooth surface wear

For open gear transmission or closed gear transmission containing unclean lubricating oil, due to the relative sliding between the meshing tooth surfaces, some harder abrasive particles enter the friction surface, resulting in changes in tooth profile, increased backlash, and excessive thinning of the gear leading to tooth breakage. In general, only when abrasive particles are mixed in the lubricating oil will it cause wear on the tooth surface during operation.

2. Tooth surface bonding

In high-speed and heavy-duty gear transmission, due to the high friction and relative speed between the tooth surfaces, the temperature in the meshing area is too high. once the lubrication conditions are poor, the oil film between the tooth surfaces will disappear, causing direct contact between the metal surfaces of the two teeth, resulting in mutual adhesion. When the two tooth surfaces continue to move relative, the harder tooth surface tears off some of the material on the softer tooth surface along the sliding direction, forming grooves.

3. Fatigue pitting

When two meshing teeth come into contact, the force and reaction force between the tooth surfaces cause contact stress on the two working surfaces. Due to the changing position of the meshing point and the periodic motion of the gear, the contact stress changes in a pulsating cycle. Under the action of this alternating contact stress on the tooth surface for a long time, small cracks will appear at the tool marks on the tooth surface. Over time, this type of crack gradually expands laterally on the surface, forming a circular shape, causing small areas of peeling off on the surface of the gear teeth and forming some fatigue shallow pits.

4. Tooth breakage

In operational engineering, gears that bear loads, like cantilever beams, will experience cracks at the root when the periodic stress at the root exceeds the fatigue limit of the gear material, and gradually expand. When the remaining part cannot withstand the transmission load, tooth breakage will occur. Gear breakage may also occur due to severe impact, eccentric load, and uneven material during operation.

5. Plastic deformation of tooth surface

Under impact load or heavy load, the tooth surface is prone to local plastic deformation, resulting in deformation of the surface of the involute tooth profile.