What is installed in the hydraulic system to prevent the abnormal high pressure of the hydraulic circuit from causing damage to the mechanical parts?

The function of a relief valve in a hydraulic system is to prevent damage from abnormal high pressure by providing a safe exit route for hydraulic fluid when pressure exceeds a predetermined level. When the pressure in the system rises above this set limit, the relief valve opens, allowing fluid to flow back to the reservoir or another part of the system, thereby reducing the pressure. This mechanism is crucial for protecting the hydraulic components and maintaining the integrity of the entire system, as excessive pressure can lead to failures or catastrophic damage to parts such as hoses, fittings, and cylinders.

While the other options play important roles within a hydraulic system, they do not serve this specific purpose. A suction valve regulates the intake of hydraulic fluid but does not manage excess pressure. A safety valve is sometimes used interchangeably with a relief valve, but they typically refer to different systems or applications. A pressure gauge indicates the system's current pressure but does not actively control or mitigate pressure levels. Thus, the relief valve is the correct component designed explicitly to manage and prevent damage from high pressure in hydraulic circuits.