The temperature of the hydraulic oil increases as the hydraulic system works.

The normal working temperature of hydraulic oil is 30℃-50℃, with a maximum of 70℃. Otherwise, the oil viscosity will decrease, enhancing the leakage risk and speeding up oil deterioration. If the oil temperature is still above 70℃ after being cooled via only the oil tank, it is very necessary to use the oil cooler.

Oil coolers are used to cool the hydraulic oil when the hydraulic systems work, maintaining the thermal balance and maintaining the temperature of the systems within 35℃-55℃. The oil coolers are usually mounted in the oil return lines of the hydraulic systems. Heavy duty equipment or hydraulic systems generating a lot of heat are equipped with independent cooling systems whose vital element is the oil cooler.

While the hot hydraulic oil passes through the oil coolers, the outside air is forced to flow through the core areas of the oil coolers to cool the hydraulic oil to the normal working temperature. By doing so, the system components are protected from damage which might be caused by hot hydraulic oil. Water can also be used as the coolant to cool the hydraulic oil. Different types of oil coolers are utilized for different applications. Both the air-cooled oil coolers and the water-cooled oil coolers work with the same heat exchange principle.

For air-cooled oil coolers, fans are used to push air through the core areas to dissipate the heat from the hot hydraulic oil. The air-cooled oil coolers feature a simple structure with relatively lower cooling efficiency. This type of oil coolers usually needs to be produced with larger sizes to improve the cooling effects. Water-cooled oil coolers are heat exchangers by means of forced convection, delivering a better cooling efficiency as compared to the air-cooled oil coolers of the same size.