Fault Analysis Of Motorcycle Gear Damage

There are many kinds of motorcycle gear, such as master and driving gear, change gear, start gear, rear driving gear, balancing gear, timing gear, tachometer gear and fuel pump gear.The function of motorcycle gear is to transfer power or change the speed.But due to the different position, the working load is also different, such as shock, pulse, distortion and bending. Then, the breakdown is different too. There are two types of the damage, one is gear noise and the other is gear damage.Here is some analysis about some common gear damage, like gear tooth face wear, gear fatigue and gear tooth broken. 

• Gear tooth face wear

Tooth face is wore to shine, tooth thickness become thinner, wear rim between working face and non contact face, even worse, gear top become pointy, diameter become smaller, and the entire tooth disappeared.The specific reasons are:

1. There are sand and dirt inside the lubricating oil. Especially in dusty areas, if the motorcycle engine sealing is not good, it easily does harm to cheap brakes, which will wear and tear.
2. The hard tooth face is too rough and there will be large frictional resistance when meshing, the soft tooth face will be chipped and wear out soon.
3. The viscosity of motorcycle lubricatingoil is low, then the oil film will be not thick enough.
4. The gear tooth face is not hard enough, or the depth of hardened layer is too enough and can’t wear well.
5. The gear tooth thickness is too big or the center distance is too small, which will cause the meshing clearance is too small to form the oil film and then wear out.

Resolution:

1. Make sure the sealing of the motorcycle engine lubrication system, change the seal gasket or apply seal glue after disassembling the gearbox to avoid dust. At the same time, replace lubricating oil timely as required.
2. Improve the precision of tooth face, especially the hard tooth when there are a large gap between a pair of hard and soft tooth, there must have low roughness.
3. Use the oil with high viscosity.
4. Ensure the quality of heat treatment, especially the depth of hardening layer and surface hardness.
5. Control the thickness and the box center distance to ensure the machining quality,

Example:

1. Fault.  Riding a motorcycle after 5000 km, the odometer did not turn. Open the motorcyle gear, found that the personal watercraft parts or motorcycle sprocket have been wore out.
2. Detection.   Check the appearance. There is no lubricating oil inside the motorcycle gear box and there is a lot of dust and other dirt on the gear face. And there is no problem with tooth face roughness and lubricant viscosity. Measure the defective part, the tooth thickness has decreased significantly which indicate there is some problem on heat treatment of the motorcycle gear, but there is no pitting on the surface, that is to say, there is no defect with surface hardness, maybe the fault happened for that hardness of layer depth is not enough.
3. Analysis.   From the above test, there are two main cause of motorcycle gear wear. One is poor sealing of the gear box, which will cause the dust and dirt come into the gear box and then grinding the tooth face. The other is the low hardness of driving tooth, which will increases the wear and tear of the gear.