1. Unit Four Control of Hydraulic Energy Hydraulic energy must be controlled in order to accomplish useful work and be safe. There are three quantities that must be controlled. Pressure Direction Flow

2. Valves As stated earlier, there are three quantities that must be controlled and they are all controlled by valves. All valves consist of basically the same parts. They each have a body, internal moving part, and ports to connect the valve to the system.

3. Pressure Control Valve Since the pump can’t tell what resistance is present in the system, it will apply what ever force is required to overcome the resistance.

4. Directional Control Valve Fluid must be directed to different points in order to control an actuator. The DCV controls where the fluid goes.

5. Flow Control Valve The basic operation of the flow control valve is to “pinch” off flow to adjust the speed of an actuator.

6. Simple Hydraulic System This type of drawing is referred to as a “pictorial”diagram.

7. Simple Hydraulic System This illustration is called a “schematic” diagram and is commonly used in industry.

8. Hydraulic Symbols These are some of the most often used symbols you will see in industry and this course. Make a point to become familiar with them.