What does the relief valve protect in the 15-gpm hydraulic circuit?

The relief valve plays a crucial role in a hydraulic circuit by ensuring that the system operates within safe pressure limits. Specifically, in a 15-gpm hydraulic circuit, the relief valve is designed to protect components such as the steering, brakes, and outrigger systems. These systems are critical for the safe operation of machinery, and excessive hydraulic pressure could lead to damage or failure, compromising safety.

The relief valve functions by releasing hydraulic fluid back to the reservoir when the pressure exceeds a predetermined limit, thereby preventing potential system overloading. This protective measure is essential for the longevity and reliability of the hydraulic systems involved, ensuring efficient operation without risk of catastrophic failure.

In contrast, the other choices serve different functions within the hydraulic system. For instance, while the boom extend/retract function (one of the options) is important, it is not what the relief valve primarily protects in this context. Similarly, joystick manipulators and hydraulic swivel assemblies have their own specific functionalities and protection measures but are not the primary focus of the relief valve's protective capabilities. The emphasis on protecting steering, brakes, and outriggers ensures the overall safety and functionality of the hydraulic system in operation.