Wear Characteristics and Maintenance Tips: Rasp Bars

Worn components in the threshing area affect the overall combine performance.  Rasp bar wear can be detected in three ways:

·        Wear in the center portion of the rasp bar

·        Wear of the leading edge

·        Wear of the serration height

If the leading edge of the rasp bar is worn away more than 1/8-in., feeding could be reduced in small grains or soybeans, because the rasp bar cannot aggressively grab the material.  Rasp bars with worn serrations will provide poor threshing and require frequent concave adjustment. 

When the height of the serration is 1/4-in. at the deepest point, the bar should be replaced.  In windrowed crops, not uniformly spread over the total width of the threshing system, the rasp bars should be replaced if they are worn more than 1/8-in. below a straight edge.

Whenever a rasp bar is replaced, the mating bar, located 180 degrees on the opposite side of the cylinder, must also be replaced to maintain cylinder balance.  Replacement bars are sold in matched sets of right-hand or left-hand patterns.  When wear on the rasp bar occurs, it is recommended to replace all of the bars on the cylinder.