What Caused the Failure of Concrete Pump Piston ?

The Failure of Zoomlion Concrete Pump Piston

One side of the concrete piston seal on an A ZLJ5412THB125-49 Zoomlion concrete boom pump was damaged after only pumping 800CBM concrete, while the piston seal on the other side was normal. The piston seal was removed and inspected to find that the piston lip was peeled off .

concrete pump piston repair

Zoomlion delivery piston

What Caused The Failure of Concrete Pump Piston

Let’s check with SANF Technical Expert Together

 


Step 1 Check the lubrication system of the concrete pump piston.

Because the other side of the concrete pump piston seal is used normally, there is no problem with the lubrication system, which can be ruled out.

Step 2 Check the concrete delivery cylinder on the right side.

Check the concrete delivery cylinder on the right side to see if there is any chromed layer falling off and strain. During the inspection, it was found that the right transition sleeve was worn by the concrete pump piston.

Step 3 No-load anti-pump and mark the delivery cylinder and transition sleeve with a marker.

After the anti-pump runs for some time, the mark on the transition sleeve is gone, and the trace is about 2cm beyond the sleeve. So we could see the problem of the piston is directly related to this.

Step 4 Check the concrete pumping pressure.

During the pumping, the pressure of the left and right delivery cylinders is the same and the instantaneous pressure of the reversing is also almost the same. There is no situation of reversing pressure, which can rule out the possibility that the reversing is not timely(also cleaning or replacing the logic valve, hydraulic reversing valve, electromagnetic reversing valve, etc.).

Disassemble and clean the check valve on the main oil cylinder, and no abnormality is found.

Step 5 Carefully observe the stroke of the concrete pump piston.

Carefully observe the stroke of the concrete pump piston and find that when the piston returns to the water tank, the strokes of the left and right cylinders are different. The distance between the right piston and the water tank is larger than the distance between the left piston and the water tank, which is about 2cm.

It means the right oil cylinder protrudes more and retracts less, but the overall stroke has not changed. The only reason for this is that the piston head of the main oil cylinder slips out, but does not fall off completely.

Step 6 Disassemble and inspect the main oil cylinder.

Disassemble and inspect the main oil cylinder. After pulling out the piston rod, it is found that the piston head has indeed slipped out because the locking screw fails.

After fixing the locking screw and reassembling the main oil cylinder, the fault is eliminated and the piston stroke is normal. The technical person find the reason for the damaged concrete pump piston successfully after carefully checking step by step. The problem is not caused by the quality of the concrete pump piston, but by a little locking screw.

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