Which of the following is a minimum requirement for a hydraulic system?

• A. Device to use the power
• B. Lubrication system
• C. Source of Power
• D. Reservoir

Answer: (C)

A hydraulic system must have a source of power to generate hydraulic pressure. The pump or power unit provides the energy that moves fluid and creates pressure, which is what drives any hydraulic work. Without this energy input, there is no flow or pressure regardless of how many valves, reservoirs, or lines are present, so no work can be performed.

The other components are important for practical operation—discovering or using that pressure is done by a device that converts hydraulic pressure into motion, lubrication helps reduce wear, and a reservoir stores the fluid—but none of them alone creates the pressure needed to start the system. The energy source is what makes hydraulics possible, so it is the minimum requirement.