Chapter 6: Control Components in a Hydraulic System

6.1 Objectives

After reading this chapter, the student will be able to:

• Learn about the various control components used in hydraulics

• Understand the purpose, construction and operation of different valves such as pressure control valves, direction control valves and flow control valves and also identify the related graphical symbols in a hydraulic circuit

• Understand and explain the different methods of valve actuation

• Differentiate between compensated and non-compensated flow control

• Explain the purpose, design and operation of servo valves

• Understand the concept of hydraulic fuses

• Understand the function and purpose of shock absorbers in hydraulics

• Learn about the operation of different types of temperature and pressure switches.

6.2 Introduction

One of the most important considerations in a hydraulic system is control . For any hydraulic system to function as required, a proper selection of control components is quite essential. Fluid power is primarily controlled with the help of control devices called valves. The selection of these control devices involves not only choosing the right type but also the size, actuating technique and its remote control capability.

In this chapter, we shall review in detail the working of various control devices in hydraulic systems that are as listed below:

• Control valves

• Servo valves

• Hydraulic fuses

• Temperature and pressure switches

• Shock absorbers.

6.3 Control valves

A valve is a control device used for adjusting or manipulating the flow rate of a liquid or gas in a pipeline. The valve essentially consists of a flow passage whose flow area can be varied. The external motion...