What device converts hydraulic energy generated by a pump back into mechanical energy?

The device that converts hydraulic energy generated by a pump back into mechanical energy is the actuator. Actuators are essential components in hydraulic systems, as they use the pressurized fluid provided by the pump to create motion.

When hydraulic fluid flows into the actuator, it generates force by moving a piston or a similar component, thereby transforming the hydraulic energy into mechanical energy that can perform work, such as moving an object or driving machinery. This transformation is crucial in various applications, from industrial machinery to automotive systems.

In contrast, hydraulic cylinders, while also involved in converting hydraulic energy to mechanical energy, are a specific type of actuator and do not encompass all forms of actuation. The pressure gauge measures the pressure of the hydraulic fluid but does not play a role in energy conversion. A flow control valve regulates fluid flow but does not convert hydraulic energy back into mechanical energy. Thus, the actuator is the best answer for the conversion process described in the question.