Electrical Skills Series
Mechanical Skills Series
Basic Skills Series
PC Skills (Office) Series

## iKNOW Hydraulic Power

Thirteen individual lessons make up the ITC Learning On-Line Hydraulics Library. ITC Learning’s Hydraulics library was specifically developed for beginning hydraulics technicians, mechanics, electricians, and operators who need to know about industrial hydraulic power.

### Introduction to Hydraulic Systems

Description: This is the first lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson identifies the basic components of an industrial hydraulic system and explains their functions. Formulas, including Pascal’s Law, are presented and their use in determining values in a hydraulic system is explained.

Prerequisites: None

Topics:

Power Transmission
Actuators
Reservoirs
Pumps
Directional Control Valves
Pressure Relief Valves
Pascal's Law
Horsepower
Speed and Pressure

Objectives:

• Visually identify the basic components of an industrial hydraulic system
• Describe the function of the basic components of an industrial hydraulic system
• Understand Pascal’s Law
• Use Pascal’s Law to determine the pressure and flow at a given point in a simple hydraulic system
• Describe the transmission of power through the system using a diagram of a simple hydraulic system
• Describe conditions necessary for normal operation of a pressure relief valve
• Define work and power as they relate to hydraulics
• Describe the conversion of power through the hydraulic system
• Calculate electrical horsepower and piston speed, given the appropriate variables

### Hydraulic Schematics

Description: This is the second lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson introduces the schematic symbols that represent the basic components of a hydraulic system. It explains the use of color-coding used to identify pressure and how to identify the flow path through the system using schematics.

Prerequisites: General knowledge of hydraulic systems is required. Review of the lesson, Introduction to Hydraulic Systems, is recommended.

Topics:

Reservoir and Filter
Pump and Motor
Piston Actuator and Valve
Directional Control Valve
Piston Positions
Flow Lines
Same Housing Components

Objectives:

• Identify the schematic symbols for the basic components of a hydraulic system
• Identify the pressure at a given point in a hydraulic system using color-coding
• Identify the flow path through a simple hydraulic system, given a schematic for a simple hydraulic system

### Hydraulic Fluid

Description: This is the third lesson in the iKNOW™ Industrial Hydraulic Power Library. The lesson discusses the types, properties, and functions of hydraulic fluids and the components in which they are used.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Piston Actuator Lubrication
Directional Control Valve
Fluid Characteristics
Fluid Types
Contamination
Reservoirs
Strainers and Filters
Bypass Check Valve
Piping

Objectives:

• Describe the types, properties, and functions of hydraulic fluid that make power transmission possible
• List sources of fluid contamination and ways to avoid contamination
• List the purposes of a hydraulic reservoir
• Identify the components of a hydraulic reservoir and describe their functions
• Describe the conditions necessary for proper functioning of a hydraulic reservoir
• Identify the location of hydraulic filters at various points in a schematic representation of a hydraulic system
• Describe the purposes of hydraulic filters
• Describe the purpose and function of the by-pass valve
• Describe the functions of hydraulic piping
• Describe the conditions necessary for proper functioning of hydraulic piping and connections and identify common indicators of malfunction

### Hydraulic Pump Applications

Description: The fourth lesson in the iKNOW™ Industrial Hydraulic Power Library, this lesson discusses the various hydraulic pumps and their applications. It also describes symptoms of pump malfunction.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Role of the Pump
Pressure Principles: Pumping
Cavitation and Aeration
Variable Volume System
High-Low Pumps
Variable Volume Pumps
Reversible Pumps

Objectives:

• Describe the role of the pump in hydraulic power transmission given a pictorial drawing or a system schematic
• Calculate the actual flow rate and the volumetric efficiency in a hydraulic system
• Explain the effect of the position of the reservoir in relation to the operation of the inlet side of the pump
• Recognize symptoms of pump malfunction, such as cavitation and aeration, and identify likely causes

### Positive Displacement Pumps

Description: This is the fifth lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes various positive displacement pumps and their components. The lesson explains some of the causes of system inefficiencies associated with fixed volume pumps and describes applications in which variable volume pumps are used.

Prerequisites: General knowledge of hydraulic systems is recommended.

Topics:

Vane Pumps
Vane Pump Components
Pressure Compensator Spring
Piston Pumps
Axial Pumps

Objectives:

• Identify the components of fixed and variable volume vane pumps, and describe their functions
• Identify the components of bent axis and axial piston pumps, and describe their functions
• Explain causes of system inefficiencies associated with fixed volume pumps
• Describe applications for variable volume pumps

### Hydraulic Accumulators

Description: This is the sixth lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes the common accumulators and their schematic symbols. It also describes the application and operation of an accumulator in a hydraulic system. Safety considerations for depressurizing and pre-charging an accumulator are discussed.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Purpose of Accumulators
Application
Secondary Purposes
Depressurizing
Gas-Charged Components

Objectives:

• Identify and describe the application of an accumulator in a system
• Identify common types of accumulators
• Identify safety considerations for depressurizing and pre-charging an accumulator
• Describe how an accumulator operates in a hydraulic system

### Pressure Control Principles

Description: This is the seventh lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes the functions of a pressure relief valve in a hydraulic system and the conditions necessary for normal operation of a pressure relief valve. Pressure characteristics, the relationship of pressure and flow, and depressurization are also discussed.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Pressure Characteristics
Pressure / Flow Relationship
Depressurization
Pressure Control Valves
Pressure Differential

Objectives:

• Describe the functions of a pressure relief valve in a hydraulic system using a system schematic.

### Pressure Control Operation

Description: The eighth lesson in the iKNOW™ Industrial Hydraulic Power Library, this lesson presents various pressure control valves, their operation, and components.

Prerequisites: General knowledge of pressure control principles is required. Review of the lesson, Pressure Control Principles, is recommended.

Topics:

Direct-Acting Valve
Pressure Override
Pilot Valve
Pilot Valve Components
Pilot Valve Operation
Shut Off Valve
Normally Open Valve
Pressure Relief Valve

Objectives:

• Explain the operation of a direct-acting poppet type pressure control valve
• Explain the operation of a pilot operated pressure control valve
• Explain the operation of a normally open pressure control valve
• Distinguish between the components and operation of direct-acting, pilot operated and normally open pressure control valves

### Pressure Control Valve Application

Description: This is the ninth lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes the proper operation of pressure control valves used in various applications.

Prerequisites: General knowledge of hydraulic schematics and pressure control principles is required. Review of the lesson, Pressure Control Principles, is recommended.

Topics:

Pressure Control Valves
Counterbalance Valves
Sequence Valves
Pressure-Reducing Valves

Objectives:

• Describe how a counterbalance valve operates
• Describe the proper operation of a pressure control valve in a sequencing circuit
• Describe the proper operation of a pressure control valve in a pressure reducing circuit
• Describe the proper operation of a check valve

### Directional Control Principles

It is recommended that you have some knowledge of schematics. You may wish to study Lesson 2, Hydraulic Schematics, from the Industrial Hydraulic Power Library before beginning this lesson.

Description: This is the tenth lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes various directional control valves. The lesson explains the function of the ports on a directional control valve and instructs the process of tracing the various flow paths through the valve. The lesson also describes the centering conditions and piloting arrangements commonly used with directional control valves.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Valves, Ports, and Identification
Valve Operation
Closed Center and Open Center Valves
Tandem Center and Float Center Valves
Predetermined Valve Positions
Valve Actuation
Pilot Operated Valve

Objectives:

• Identify the schematic symbols for various types of directional control valves
• Identify the functions of the ports on a directional control valve
• Trace the various flow paths through the directional control valve using a system schematic
• Describe how different kinds of directional control valves can be used to control the operation of a hydraulic cylinder using a system schematic
• Describe centering conditions commonly used in directional control valves
• Describe piloting arrangements commonly used with directional control valves

### Flow Control Valves

It is recommended that you have some knowledge of schematics. You may wish to study Lesson 2, Hydraulic Schematics, from the Industrial Hydraulic Power Library before beginning this lesson.

Description: This is the eleventh lesson in the iKNOW™ Industrial Hydraulic Power Library. The lesson demonstrates how to determine speed and flow rates and differential pressure. It describes various valves, their components, and their uses.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Speed and Flow Rate Formula
Needle Valve
Differential Pressure
Pressure Compensated Valves
Meter-Out and Meter In

Objectives:

• Explain the conditions that affect flow in a hydraulic system using a system schematic
• Explain how changing the flow rate in a hydraulic system affects the performance of the actuator using a system schematic
• Identify the schematic symbols for flow control valves
• Identify the functions of ports on a flow control valve
• Describe the operation of a needle valve, and trace the path of the fluid through the valve
• Describe the operation of a pressure-compensated flow control valve, and trace the path of the fluid through the valve
• Describe the operation of a check valve
• Describe the operation of meter-in and meter-out circuits using a system schematic

### Actuator Cylinders

Description: This is the twelfth lesson in the iKNOW™ Industrial Hydraulic Power Library. This lesson describes the various cylinders used in hydraulic actuators. It also describes the operation of a cylinder controlled by regulating flow or pressure, and the purpose of a cylinder leak test.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Single-Acting Cylinders
Double-Acting Cylinders
Drill and Clamp Cylinders
Flow Control Check Valves
Cylinder Operation
Cylinder Seals
Leakage Test

Objectives:

• Describe the difference between a single-acting cylinder and a double-acting cylinder
• Identify the schematic symbol and describe the action of a differential cylinder
• Using the schematic symbol, describe the operation and applications of a non-differential cylinder
• Describe the operation of a circuit whose cylinder is controlled by regulating flow or pressure
• Identify the components of a hydraulic cylinder using a cutaway model
• Explain the purpose of a cylinder leak test

### Hydraulic Motors

Description: This is the final lesson in the iKNOW™ Industrial Hydraulic Power Library. General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended. This lesson describes various hydraulic motors and their functions. It also describes the operation of various hydrostatic drive circuits and the function of components and flowpath in a braking circuit.

Prerequisites: General knowledge of hydraulic schematics is required. Review of the lesson, Hydraulic Schematics, is recommended.

Topics:

Rotary Motion
Motor Types
Motor Horsepower
Motors/Variable Volume Pumps
Valves Providing Braking

Objectives:

• Identify the schematic symbol for an unidirectional and bi-directional hydraulic motor
• Describe the functional similarity between a hydraulic pump and a hydraulic motor
• Describe the flow path through a hydraulic motor, using a cutaway diagram of a vane motor
• Describe the operation of a hydraulic gear motor and a hydraulic piston motor, using a cutaway diagram of each
• Express the output of a hydraulic motor in terms of horsepower
• Describe the operation of various hydrostatic drive circuits from the circuit schematics
• Describe the function of the components and the flow path through the circuit