Hydraulic Oil Temperature
One of the most common issues in a hydraulic system is overheating. Overheating is caused by inefficiencies in the system affecting the hydraulic oil temperature. It can lead to a loss of input power, as it is converted to heat…
If hydraulic oil temperature increases beyond 82°C, the seal compounds in any hydraulic component can be damaged and it oil degradation is accelerated. It goes without saying then that operating hydraulic systems at 82°C and above should be avoided; you can usually tell if the temperature is too high if the viscosity is too low for the hydraulic components. Viscosity can also be negatively affected in temperatures below 82°, depending on the oil’s viscosity index. To ensure a stable oil temperature, the hydraulic system must be able to dissipate heat much faster than it is built up.
The two most common ways of preventing overheating in your system are to either reduce the hydraulic oil temperature or increase heat dissipation.
Heat dissipation happens in hydraulic systems through the hydraulic reservoir. By checking the reservoir, you can ensure that the fluid level is correct and if it is too low, fill it to the correct level. You must also make sure there is nothing obstructing the air flow into the reservoir (this may be a build-up of dirt or debris).
If you review the heat exchangers, you can make sure that the core is not blocked. The heat exchanger relies on the flow-rate and temperature of the hydraulic oil and the coolant in order to disperse heat suitably. If you experience issues with the cooling circuit then they need to be replaced.
You can use an infrared thermometer to ensure that the performance of the heat exchanger is optimal, but you must be aware of the flow-rate of the hydraulic oil through the exchanger.
If the pressure in a system drops, heat is being generated. If any of the components in the system are leaking, they will increase the heat generation. This in turn, will allow the system to overheat. You should be able to identify any components that are leaking internally and they could be anything from a cylinder leaking fluid to a valve that hasn’t been adjusted properly.
If a relief valve is below, or too close, to the pressure setting of a pressure compensator in a closed centre circuit, then it could lead to increased heat generation; this means the pressure can’t reach the pressure the pressure compensator has been set to. The component then will continue to move oil thorough the system, passing over the relief valve, which produces heat.
If operation of a hydraulic system is continued even though the temperature is too high, then the more likely damage will be. If the hydraulic oil temperature is too high and your system is over-heating, it is best to shut it down, see what has happened to cause it to overheat and repair the damage before it becomes irreparable.
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