An Example of Fault Analysis of ABG511 Paver

1. Fault phenomenon

During the process of laying cement-stabilized soil and gravel base with the ABG5ll type paver, the left side of the road surface sometimes showed wavy patterns. After the machine ran for a certain distance, this fault disappeared, while the right side was completely normal.

2 Maintenance

After the malfunction occurred, we conducted an on-site inspection of the malfunction phenomenon. The oil circuit and electrical circuit of the automatic leveling system were inspected and found to be normal. When the sensor of the automatic leveling system was touched by hand, the hydraulic cylinder of the automatic leveling system rose and fell freely, indicating that there was no problem with the automatic leveling system. When inspecting the ironing plate lifting system, the left side moved slowly, so it was initially suspected that the electrical circuit connection points were loosely connected. However, after a comprehensive inspection, no problems were found.

In response to the malfunction phenomenon, we conducted a thorough and detailed observation of the machine's operation process and found that whenever there was a protruding part on the road surface (where the material transport vehicle often scattered materials during the process of pouring materials into the paver and the construction workers failed to handle it in time), the road surface spread out by the left screed would show waves. The greater the undulation of the road surface, the more serious the above-mentioned problems will be. For this, we conducted a simulation test: We placed a portion of gravel in front of the left track plate. When the paver passed by this area, waves appeared on the paved road surface. After moving forward for about 20 meters, the machine's operation returned to normal. However, this phenomenon does not occur when inserted under the right track plate. We suspect that there is a problem with the oil circuit or electrical circuit of the left ironing plate lifting system, which causes the hydraulic cylinder not to be in a floating state. After inspection, it was found that there was no problem with the circuit, but the solenoid valves at the oil inlet and outlet ports of the lower chamber of the hydraulic cylinder were damaged. The fault disappeared after replacement.

3 Fault analysis

The thickness of the road surface laid by the paver is adjusted by the Angle of elevation of the screed. The larger the Angle of elevation, the thicker the road surface laid. Under normal circumstances, the lifting cylinder of the ironing plate is freely floating. However, when we disassembled and inspected the solenoid valve C at the oil inlet and outlet of the lifting cylinder B on the left side of the ironing plate, we found that the solenoid valve was in a semi-closed state, that is, in the position of small orifice throttling, which caused the oil passage to be blocked.

When the track plate of the paver passes over the upper convex road surface, the front part of the paver rises. Under normal circumstances, the screed lifting cylinder should also float accordingly to keep the screed in its original position. However, due to the poor oil passage of the screed lifting cylinder on this side, a large pressure difference is generated between the upper and lower chambers of the lifting cylinder, and the lifting cylinder cannot float in time (at this time, it can be regarded as a whole). Due to the lever effect, the ironing plate is pressed down, resulting in concave waves. As the paver moves forward, there are two reasons for the increase in the paving thickness, resulting in upward convex waves on the road surface:

(1) The oil pressure in the upper and lower chambers of the lifting cylinder on the left side of the screed tends to balance, and the screed is in a free-floating state. At this time, the concave road surface that appears after paving will increase the paving elevation Angle through the automatic leveling sensor system, thereby increasing the paving thickness.

(2) When the paver moves forward to the position shown in Figure 4, due to the effect of the center of gravity, the front part of the paver drops and the rear part rises. However, the lifting cylinder cannot float in time because of the imbalance of oil pressure in the upper and lower chambers, and the screed plate is lifted along with the machine body, thereby increasing the thickness of the paving.

As the paver continues to move forward and the paving thickness increases, the oil pressure in the upper and lower chambers of the lifting cylinder on the left side of the screed tends to balance again, and the lifting cylinder is in a floating state. When the paver drives out of the convex road surface, there are two reasons for the reduction of the paving thickness:

(1) When the paver exits the upper convex section, the rear part drops. At this time, the oil pressure in the upper and lower chambers of the lifting cylinder on the left side of the screed is unbalanced, causing the lifting cylinder on this side to fail to float in time, and the screed presses down, reducing the thickness of the paving. After running for a period of time, the oil pressure in the lifting cylinder tends to balance again. Atlas air compressor parts.

(2) The increased paving thickness has exceeded the standard paving thickness. At this time, the lifting cylinder on the left side of the screed is in a floating state. The automatic leveling sensor system then reduces the paving elevation Angle, and the road surface paving can return to normal.

Through the analysis and elimination of this fault, we have the following two insights:

(1) The elimination of any fault should start from the working principle of the equipment and use theory to guide practice.

(2) We must observe carefully and think seriously. We must not overlook any small details. For instance, during the initial inspection, we found that the lifting cylinder on the left side of the screed was lifting slowly and did not pay enough attention to it (because the weights of the screed on both sides of the paver's main body are not equal, we overlooked this point).