Hydraulic Equipment Maintenance
2023-12-11
Seven mistakes frequently made in hydraulic equipment maintenance
Mistake 1-oil change
There are only two situations that require hydraulic oil replacement: degradation of the base oil or consumption of additives. Since there are too many factors that can determine the degradation rate of the oil and the consumption of additives, the hydraulic oil should be replaced according to the number of hours of use without considering the actual condition of the oil
If you continue to run with the base oil degraded or additives depleted, it will damage the life of every other component in the hydraulic system. The only way to know when the oil needs to be changed is through oil analysis.
Mistake 2-Replace the filter
A similar situation exists with hydraulic filters. If you change according to the schedule, it means that the change is too early or too late. If you replace them in advance, you will waste money on unnecessary filter replacements before the filter is exhausted. If you replace them later, the increase in particulate matter in the oil after the filter is bypassed will quietly reduce the service life of every component in the hydraulic system-which will cost more in the long run.
The solution is to replace the filter after all the dirt holding capacity of the filter is used up and before the bypass valve is opened. This requires a mechanism to monitor the limit of flow (pressure drop) through the filter element and alert you when this point is reached. The clogging indicator is the most primitive form of the device. A better solution is to continuously monitor the pressure drop across the filter.
mistake 3 : high temperature operation
How high is the temperature of the hydraulic system? It mainly depends on the oil's viscosity and viscosity index (the rate of change of viscosity with temperature), and the type of hydraulic components in the system.
As the oil temperature increases, its viscosity also decreases. Therefore, when the temperature of the hydraulic system reaches the temperature that the oil viscosity is lower than the temperature required for proper lubrication, the hydraulic system will overheat.
For example, vane pumps require a higher minimum viscosity than plunger pumps. This is why the types of components used in the system also affect its safe maximum operating temperature.
In addition to the importance of adequate lubrication (which cannot be overstated), operating temperatures above 82 degrees Celsius will damage most seals and hose compounds and accelerate oil degradation. However, due to the reasons already explained, the hydraulic system may operate at a high temperature below this temperature.
Mistake 4-Use the wrong hydraulic oil
Oil is the most important part of hydraulic system. Hydraulic oil is not only a lubricant, but also a means of transmitting power in the entire hydraulic system. This dual effect makes viscosity the most important characteristic of oil because it affects machine performance and service life.
The viscosity of the oil largely determines the maximum and minimum oil temperature at which the hydraulic system can operate safely. If the viscosity you use is too high for the climate in which the machine must be used, the lubricating oil will not flow normally or get enough lubrication during the cold start process.
If you use a lubricating oil with a viscosity that is too low for the current climate, you will not be able to maintain the minimum viscosity required on the hottest days of the year, so you will not be able to get enough lubrication.
But this is not over yet. Within the allowable viscosity limit required for adequate lubrication, there is a narrow viscosity band in which power loss is minimal. If the viscosity of the working oil is higher than the ideal value, fluid friction will lose more power. If the working viscosity is lower than the ideal value, more power will be lost due to friction and internal leakage.
Using the wrong viscosity oil will not only cause lubrication damage and premature failure of main components, but also increase power consumption (diesel or electricity), which are two things you don't want.
Despite your ideas, blindly following the machine manufacturer’s package of recommendations does not necessarily lead to the correct viscosity of oil.
Mistake 5-Wrong filter position
Any filter is a useful filter, right? error! The hydraulic filter has two positions that do more harm than good, and can quickly destroy the parts to be protected during installation. These filter locations to avoid are from the pump suction port and drain pipe.
This is contrary to the traditional view: a filter must be installed at the inlet of the pump to prevent it from being "damaged". First, the pump draws oil from a dedicated storage tank instead of a trash can. Second, if you think it is normal or acceptable for garbage to enter the hydraulic tank, then you may be wasting time reading this article.
If you want to maximize the service life of the pump (as it should), it is more important to fill the pump chamber freely and completely with oil during each oil intake than to protect the pump from nuts and bolts.
These are not dangerous in a properly designed fuel tank where the suction port of the pump is at least 100mm from the bottom of the fuel tank.
Studies have shown that restricting air intake can shorten the service life of gear pumps by 56%. Moreover, for vane pumps and plunger pumps, the situation is even worse, because these designs cannot withstand the vacuum created by restricted air intake. The design of hydraulic pumps is not based on "suction".
Installing a filter on the drain line of the plunger pump and the motor can cause a series of different problems, but the result is the same as the suction filter. They shorten the service life and cause catastrophic failure of these expensive components.
Mistake 6-Believe that hydraulic components are self-priming and self-lubricating
If the correct steps are not followed during the initial start-up, hydraulic components will be severely damaged. In some cases, they may work for a while, but the damage caused at startup is doomed to premature failure.
The process of solving this puzzle is divided into two parts: knowing what to do and remembering to do it. Not knowing what to do is one thing. However, if you do know it but forget to do so, it will be devastating.
If you forget to open the oil suction shut-off valve before the motor starts, there is no guarantee that the pump housing will be filled with enough lubricant!
Mistake 7-not receiving education in hydraulics
The purpose of this article is to show that if you own, operate, repair or maintain hydraulic equipment, and you are not aware of the latest hydraulic equipment maintenance practices, you may spend a lot of money.
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