Whether in special vehicles or conventional ones, the engine holds significant importance. In the case of truck-mounted cranes, the engine is no less crucial. These cranes operate in complex and ever-changing environments over extended periods, and the cylinders of their engines are prone to experiencing abnormal deformation, thereby influencing the performance, economy, and service life of the engine. Subsequently, if we can grasp the reasons behind the abnormal wear of the cylinders, we can essentially address this issue at its root, which is of paramount importance for prolonging the engine’s lifespan.
The causes of engine cylinder wear can be classified into two major aspects: one is attributed to structural factors, and the other stems from improper usage. The details are as follows:
Abnormal wear caused by structural reasons:
Poor lubrication conditions can lead to severe wear in the upper part of the cylinder liner. The upper section of the cylinder liner is in close proximity to the combustion chamber, where temperatures are extremely high and lubrication conditions are less than ideal. The scouring and dilution effects caused by fresh air and unevaporated fuel exacerbate the deterioration of the upper conditions, resulting in the cylinder being in a state of dry friction or semi-dry friction. This is the primary reason for the significant wear observed in the upper part of the cylinder.
The intense heat near the combustion chamber causes the lubricating oil to thin and lose its effectiveness more rapidly. At the same time, the high temperatures can also cause the lubricant to break down and form deposits that further impede proper lubrication. The combination of these factors significantly increases the friction and wear in this area.
There is also excessive pressure exerted on the upper part of the cylinder, causing the wear to be more pronounced at the top and relatively less at the bottom. Under the influence of the self-elastic force and back pressure of the piston ring, it is firmly pressed against the cylinder wall. The greater the positive pressure, the more challenging it becomes to form and maintain the lubricating oil film, thereby intensifying the mechanical wear. During the power stroke, as the piston moves downward, the positive pressure gradually diminishes, consequently leading to severe cylinder wear.
The high pressure at the top of the cylinder is a result of the combustion process, where the force generated pushes the piston against the cylinder wall with significant force. This pressure, combined with the less favorable lubrication conditions, contributes to the accelerated wear at the upper portion of the cylinder.
Minerals and organic acids can cause the surface of the cylinder to corrode and flake off. After the combustible mixture gas within the cylinder undergoes combustion, water vapor and acidic oxides are generated. These substances dissolve in water to form mineral acids. Coupled with the organic acids produced during the combustion process, they exert a corrosive effect on the surface of the cylinder. During the piston’s movement, the corrosive substances are gradually scraped off by the piston ring, leading to the deformation of the cylinder liner.
The chemical reactions that occur during combustion produce acidic byproducts that, when combined with moisture, create an acidic environment within the cylinder. This acidic environment attacks the metal surface of the cylinder, gradually weakening it and causing material to flake off, contributing to the overall wear and damage.
The entry of mechanical impurities causes severe wear in the middle of the cylinder. Dust present in the air, impurities within the lubricating oil, etc., find their way between the piston ring and the cylinder wall and give rise to abrasive wear. When dust or impurities reciprocate with the piston within the cylinder, since the movement speed is at its highest in the middle of the cylinder, the wear in this area is exacerbated.
The presence of these foreign particles acts like sandpaper, constantly rubbing against the cylinder wall and causing microscopic scratches and grooves. Over time, this abrasive action leads to significant wear and damage, particularly in the middle of the cylinder where the movement is most intense.
Wear caused by improper use:
Ineffective filtering by the lubricating oil filter. If the lubricating oil filter fails to function properly, the lubricating oil cannot be effectively filtered. Lubricating oil containing a large quantity of hard particles will undoubtedly aggravate the wear on the inner wall of the cylinder liner.
A poorly functioning filter allows contaminants to pass through and reach the cylinder, where they cause abrasive damage. Regular maintenance and replacement of the oil filter are essential to prevent this.
Long-term low-temperature operation. When the truck-mounted crane operates at low temperatures for an extended period, it first leads to suboptimal combustion, and carbon deposits accumulate from the upper part of the cylinder, causing severe abrasive wear in this area. Secondly, it induces electrochemical corrosion.
Low temperatures can affect the fuel’s vaporization and combustion efficiency, resulting in incomplete combustion and the formation of deposits. Additionally, the low temperature can increase the corrosive effects of moisture and acidic substances within the engine.
Frequent use of inferior lubricating oil. Inferior lubricating oil can corrode the upper part of the cylinder liner. If this persists, it will gradually undermine the performance of the engine.
Poor-quality lubricants may lack the necessary additives and protective properties, leaving the cylinder vulnerable to wear and corrosion. It is crucial to use high-quality lubricants that are suitable for the engine’s specifications and operating conditions.
In reality, there are numerous reasons for the abnormal wear of the engine cylinder in truck-mounted cranes. The abovementioned two categories are the main and commonly encountered ones. Understanding and addressing these causes can go a long way in maintaining the engine’s health and performance, reducing the likelihood of premature cylinder damage and extending the overall lifespan of the vehicle.
In conclusion, proper maintenance, regular checks, and the use of quality components and lubricants are essential for minimizing cylinder wear and ensuring the smooth and efficient operation of truck-mounted cranes. By being vigilant and proactive in dealing with these issues, operators can maximize the reliability and longevity of their equipment.
