Not all the damage that we see come into our shop here a Texas Final Drive is dramatic -- sometimes it takes a trained eye to spot the problem. A good example of that is scoring of key components, like the cam ring out of a radial piston hydraulic motor. In this Shop Talk Blog post, we are going to talk about scoring, its causes, why it’s serious, and how to prevent it.
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Scoring
Scoring is a type of abrasive wear that occurs when two surfaces interact with each other resulting in uneven scratches or cuts. Severe scoring may also be referred to as galling, scuffing, or seizing. It typically looks like long scratches occurring along the direction of motion. This image shows scoring on a cam ring taken from a radial piston hydraulic motor.
Causes of Scoring
There can different causes behind scoring. Scoring can occur when pressing bearings or hubs either onto or off shafts. Sometimes heat will cause a part such as a shaft to expand enough that it cannot move in its bearing, also resulting in scoring. Scoring can affect gear teeth and will appear as radial scratch lines. However, the most common cause of scoring that we encounter is due to contamination of the lubricant or hydraulic fluid. When abrasive particles like dirt or flakes of metal are trapped in the lubricant, they eventually cause scoring.
Why is Scoring a Big Deal?
Obviously, scoring is not a good sign inside a final drive -- it compromises the performance of the final drive motor. When expensive parts are scored, they are usually reground or lapped if possible. Cheaper parts are simply replaced. Some parts can be destroyed if they are severely scored, such as the cam ring in a radial piston final drive motor or the distributor in the rotary group from an axial piston final drive motor. Any way you look at it, damage from scoring can be expensive.
Preventing Scoring in Your Final Drive
Scoring can be prevented through proper lubrication, which includes not just checking fluid levels but changing out the fluids per manufacturer recommendations. When it comes to shafts and bearings, proper alignment and adjustment are key to preventing binding and scoring, so care needs to be taken with their installation. If you aren’t use to making these kinds of repairs, then installing new bearings and shafts may best be left to a professional.
One of the major causes of radial piston motor failure is contamination: when abrasive particles make their way into the final drive motor, scoring is going to result. Clean practices must be used when opening up a final drive motor, or changing out its fluids. If there has been a catastrophic failure somewhere in your hydraulic system, including the final drive motor or main pump, then it’s a good idea to flush the system to make sure no damaging contaminants that developed are left behind.
Conclusion
Scoring is a common problem in final drive motors, and it can lead to some expensive repairs. It can be prevented through proper lubrication, careful installation of bearings and shafts, avoiding contamination. Remember that if a part is scored badly enough, it may have to be replaced -- prevention is the best way to deal with scoring.
Texas Final Drive is your partner in providing new or remanufactured final drive hydraulic motors from a single mini-excavator to a fleet of heavy equipment. Call today so we can find the right final drive or hydraulic component for you, or check out our online store to find your O.E.M. manufacturer brand motor now.
