Industry News

Reasons for the Wear of the Front Cylinder of the Dump Truck (2)

2021-11-11
Reasons for the wear of the Telescopic Cylinder for Dump Trailer 
(3) The hard chromium plating layer on the inner surface of the cylinder body peels off. It is generally believed that the reasons for the peeling off of the hard chromium plating layer are as follows.
a. The plating layer is not well bonded. The main reasons for the poor adhesion of the electroplating layer are: before electroplating, the degreasing and degreasing treatment of the parts is insufficient; the surface activation treatment of the parts is not thorough, and the oxide film layer is not removed.
b. The hard rim layer is worn out. The wear of the electroplated hard chromium layer is mostly caused by the grinding action of the friction iron powder of the piston. When moisture is trapped in the middle, the wear is faster. The corrosion caused by the difference in the contact potential of the metal only occurs in the parts that the piston touches, and the corrosion occurs in points. Same as above, when moisture is trapped in the middle, it will promote the development of corrosion. Compared with castings, the contact potential difference of copper alloy is higher, so the corrosion degree of copper alloy is more serious.
c. Corrosion due to contact potential difference. Contact potential difference corrosion is not easy to occur for hydraulic cylinders that operate for a long time; it is a common failure for hydraulic cylinders that have been stopped for a long time.
(4) Damage to the piston ring The piston ring is damaged during operation, and its fragments are caught in the sliding part of the piston, causing scratches.
(5) The material of the sliding part of the piston is sintered to cast the piston, which will cause sintering when subjected to a large lateral load. In this case, the sliding part of the piston should be made of copper alloy or welded with such materials.
3. Foreign matter is mixed in the Telescopic Cylinder for Dump Trailer
Among the failures of the hydraulic cylinder, the most problematic is that it is difficult to judge when the foreign matter enters the hydraulic cylinder. After foreign matter enters, if the outer side of the piston sliding surface is equipped with a lip seal, then the lip of the seal can scrape the foreign matter during operation, which is beneficial to avoid scratches. However, the piston with O-shaped sealing ring has sliding surfaces at both ends, and foreign objects are sandwiched between the sliding surfaces, which can easily form scars.
There are several ways for foreign bodies to enter the tank.
(1) Foreign matter entering the hydraulic cylinder
a. Since the oil port is not kept open during storage, there will be conditions for accepting foreign objects at all times, which is absolutely not allowed. When storing, it must be filled with anti-rust oil or working oil and plugged properly.
b. Foreign matter enters when the cylinder is installed. The place where the installation operation is carried out is in bad conditions, and foreign objects can enter unconsciously. Therefore, the area around the installation site must be cleaned up, especially the place where the parts are placed must be cleaned up, so that there is no dirt.
c. There are "burrs" on the parts, or insufficient scrubbing. There are often burrs left during drilling in the oil port on the cylinder head or in the buffering device. Pay attention to it and install it after the sand is removed.
(2) Foreign matter generated during operation
a. Friction iron powder or iron filings due to the unusual strength of the cushion plunger. The fit clearance of the cushioning device is very small, and when the lateral load on the piston rod is large, it may cause sintering. These friction iron powder or metal fragments that have fallen off due to sintering will remain in the cylinder.
b. Scars on the inner surface of the cylinder wall. The high pressure on the sliding surface of the piston causes sintering, so that the inner surface of the cylinder is squeezed, and the squeezed metal falls off and stays in the cylinder, causing scars.
(3) There are many cases of foreign matter entering from the pipeline.
a. Not paying attention when cleaning. When the pipeline is installed and cleaned, it should not pass through the cylinder, and a bypass pipeline must be installed in front of the oil port of the hydraulic cylinder. this point is very important. Otherwise, the foreign matter in the pipeline will enter the cylinder, and once it enters, it is difficult to remove it outward, but it will be transported into the cylinder instead. Furthermore, when cleaning, consider the method of removing foreign objects in the installation pipeline operation. In addition, for corrosion in the pipe, pickling and other procedures should be carried out before the pipeline is installed, and the rust must be completely removed.
b. Chips formed during pipe processing. After the pipe is cut to length, there should be no leftovers during the deburring operation at both ends of the pipe. In addition, placing steel pipes near the site where welding pipeline operations are performed is the cause of the influx of welding foreign matter. For pipes placed near the welding operation site, the nozzles must be sealed. It must also be noted that the pipe fitting materials should be prepared on a dust-free workbench.
c. The sealing tape enters the cylinder. As a simple sealing material, PTFE plastic sealing tape is often used in installation and inspection. If the winding method of linear and ribbon sealing materials is wrong, the sealing tape will be cut off and enter the cylinder. The belt-shaped seal has no effect on the winding of the sliding part, but it will cause the cylinder's one-way valve to not work well or cause the buffer control valve to be unable to adjust to the end; for the circuit, it may cause the reversing valve and overflow The operation of the valve and the pressure reducing valve is out of order.
Telescopic Cylinder for Dump Trailer