What are the common misunderstandings about lubrication for construction machinery?

1. It's better to have more engine oil than less

We know that a low level of engine oil can lead to insufficient oil supply and poor lubrication, causing mechanical accidents. So, when refueling, one should not "rather add more" just because they are afraid of running out of fuel. In fact, excessive oil not only increases the power consumption of the crankshaft due to increased rotational resistance, but also makes the oil prone to bubble formation, emulsification and leakage, resulting in poor lubrication.

2.Engine oil with high viscosity is more beneficial to the engine than that with low viscosity

If the viscosity grade of the lubricating oil is selected too high, it will cause poor pumping performance of the oil pump, reduced flow rate, and deteriorate its lubricity, washability and heat dissipation. It is also prone to semi-dry friction of the machine parts, leading to faults such as bearing seizure and shaft seizing.

3. Using high-viscosity engine oil can solve the problems of weak engine operation and oil leakage

Weak engine operation, excessive oil consumption and oil leakage are external signs of deteriorating engine technical condition. The claim that "high-viscosity engine oil can solve the above problems" is not supported by sufficient evidence. On the contrary, it will increase the starting resistance of the engine, deteriorate the lubrication performance and accelerate the wear of the components.

4. Change the oil to the grade required by the machine without any change

The oil grade specified in the mechanical user manual is for general working conditions. In the practice of machine oil change and maintenance, the actual usage conditions should also be taken into account. If the actual usage conditions are more stringent than the specified ones, a higher grade of oil should be selected (through tests), or the oil change cycle should be appropriately shortened.

5. If the lubricating oil turns black, it indicates that it has deteriorated

Modern lubricating oils all contain appropriate amounts of various additives to improve their lubricating performance. It is a normal phenomenon for internal combustion mechanical lubricating oil with added detergents and dispersants to turn black after a short period of use. One should not think that "the oil has deteriorated" and replace it easily. Lubricating oil with additives often causes the surface of bearings to turn black during use, which is also a normal phenomenon. Therefore, when determining whether the lubricating oil has deteriorated, we cannot rely solely on visual judgment but need to conduct a comprehensive analysis. When conditions permit, the oil should be tested and analyzed to ensure that the oil is changed according to its quality.

6.Full hub lubrication is more effective than empty hub lubrication

In the oil change, maintenance and repair work of machines, it is often observed that in addition to filling the hub bearings with grease, the cavity of the hub is also filled. This greasing method is conventionally called "full hub lubrication". Practical experience has shown that the hub bearing is best lubricated by an empty hub. The so-called "hub lubrication" means that the hub bearings are fully coated with grease, while only a thin layer of grease is applied to the inner cavity of the hub for rust prevention. "Full hub lubrication" not only wastes grease but also, due to excessive grease, increases internal friction, raises the temperature rise of the bearing, and causes grease loss. In severe cases, the lost grease may seep into the braking system, causing brake failure and resulting in an accident.

The users, managers and maintenance personnel of construction machinery should recognize the above-mentioned misunderstandings in lubrication to ensure that all links such as oil change and maintenance of the machines are in a virtuous cycle.