The phenomenon of "loader bucket not reaching the correct position" refers to the situation where, after the loader's working device operates for a period of time, the bucket's limit block fails to make contact with the boom, and the bucket angle does not reach the specified value.
This phenomenon is mainly caused by insufficient structural strength of the working device components, leading to plastic deformation. When designing the working device, we often analyze the stress on the working device under full load during material insertion, assuming that the working device experiences the greatest stress under this condition. However, this is not always the case. Based on our experience, we have identified several other situations that can cause plastic deformation, which we have previously overlooked. We are highlighting these situations here so that they can be considered in future working device structural strength analyses.
1. When designing the working device, to prevent material spillage during transportation, we adjust the pivot point connecting the bucket cylinder to the front frame. This ensures that during the arc movement from the ground-level bucket position to the specified transport position, the bucket's limit block remains tightly against the boom. This protects the working device from impact, prevents material spillage, and simplifies driver operation, eliminating the need for a separate bucket retraction operation after reaching the transport position.
2. When unloading at the highest point, users often raise the bucket cylinder to ensure complete unloading, causing the bucket limit block to violently collide with the boom. Over time, this creates a dent in both the bucket limit block and the boom, and the bucket's unloading angle far exceeds the design value. At this point, the working device's linkage mechanism is close to a dead point, meaning points A, B, and C are almost in a straight line. Further bucket retraction will subject the connecting rod and push arm to infinitely large tensile forces. To prevent this phenomenon, an effective solution is to weld a limit block between the arm and the boom to prevent excessive impact between the bucket and the boom.
