The oil cooler is a central component in the hydraulic system of every construction machine. Hydraulic oil heats up through throttling, friction, and pressure losses in the system — during intensive excavator operation, temperatures can exceed 100 °C without cooling. Optimal temperature ranges from 40–60 °C; above 80 °C, oil degradation accelerates exponentially.
Construction equipment predominantly uses air-oil coolers (fin coolers with fan), rarely water-oil coolers. The cooler is typically positioned next to the engine cooler at the rear of the upper structure. On large excavators of 30 tons and above, two separate cooling circuits are often installed: one for the working hydraulics, one for the drive system.
Contamination of the cooler fins by dust, pollen, and fibers is the most common cause of overheating problems on construction sites. Regular cleaning with compressed air (not high-pressure washers!) is therefore essential. Modern machines electronically monitor oil temperature and automatically reduce engine output in case of overheating.