Inefficiencies cause the hydraulic fluid to overheat, which results in loss of input power. The loss of input power is converted into heat. Thus, the heat load of a hydraulic system is equal to its total power lost due to inefficiencies.
On that note, when the total input power that was lost is greater than the heat that was dissipated, it means the hydraulic system will overheat in the long run. Depending on the type of hydraulic system, the typically installed cooling ability is between 25 to 40% of input power.
Hydraulics has a lot of advantages when it comes to power transmission. However, hydraulics is not at all overall efficient. The fact is that every hydraulic machine needs to have high and continuous power input as well as power output and needs an oil cooler. The oil cooler is important in ensuring that the oil temperature is stable and within the standard limits.