It's usually when a job is completed or during a random maintenance inspection that someone notices that flails have worn excessively on one side. Normally flails should wear evenly around the perimeter. There are two possible causes for excessive wear to one side.
1. The flails were loaded too tightly on the drum shafts. Spinning allows the wear to be distributed evenly about the flail's perimeter. If the flails are tight and cannot spin properly, wear will occur predominantly on one side.
Even if manufacturer's guidelines are followed and the correct number of flails and spacer washers were loaded, variances in manufacturing tolerances and material thickness may require slight adjustments in the field.
Bottom line: Adjust the number of flails and spacer washers so they spin freely.
2. While on the jobsite, the operator raised the forward wheels off the surface. This causes the machine weight to be incorrectly supported by the rotating drum. The flails will not spin properly, creating excessive wear on one side.
Despite some beliefs, raising the machine off its front wheels does not increase—and actually decreases—the material removal rate. This is because the resulting increase in recoil forces makes the surface planer unstable. The more a machine hops or jumps, the less kinetic energy it can effectively transfer to the surface.
Bottom line: Keep the wheels in contact with the surface.
Click here to read the article on flail selection.