Rotary drilling rigs have three major systems: the hydraulic system, engine system, and electrical system. These three systems are very important for the entire equipment, determining the working efficiency and performance of the equipment. Many rotary drilling rig parts, such as hydraulic parts, engine parts, and electrical parts, actually serve these three systems. Given the importance of these three systems, issues like the hydraulic system's oil overheating and high temperature can cause faults such as inflexible operation, discontinuous work, lack of power, and reduced working pressure. Today, we will analyze the reasons for oil overheating:

1. The tank volume is too small, the heat dissipation area is insufficient, no oil cooling device is installed, or although there is a cooling device, its capacity is too small.

2. The quantitative pump supply system, which selects the pump capacity based on the rapid advance speed, will have most of its excess flow returning from the overflow valve under high pressure and generating heat during operation.

3. Faults in the system's unloading circuit or the absence of an unloading circuit mean that when work stops, the pump cannot unload. The entire flow of the pump overflows under high pressure, causing overflow loss and heat, leading to oil overheating.

4. The system's piping is too thin, too long, or has too many bends, resulting in significant local and along-the-way pressure loss.

5. The precision of components is not enough, and poor assembly quality leads to large mechanical friction losses in relative motion.

6. The mating clearance of the fitting parts is too small, or wear and tear lead to excessively large clearances, causing large internal and external leakage and significant volumetric loss. For instance, the volumetric efficiency of the pump decreases, leading to rapid heating.

7. The hydraulic system's working pressure is adjusted higher than actually needed. Sometimes this is due to over-tight seals, or the need to increase pressure to compensate for damaged seals and increased leakage.

8. Rotary drilling rigs operating in summer face higher oil temperatures due to the climate and high ambient temperatures.

9. Improper selection of oil viscosity can also cause overheating. High viscosity leads to high viscous resistance, while too low viscosity increases leakage. Both situations can cause oil overheating and excessively high temperatures.