Pneumatic and Hydraulic Maintenance

Table of Contents

Chapter 1: Principles of Pneumatics

Topics: Fluid power systems; Force, weight, and mass; Pressure; Work and energy; Diffusion and dispersion; Compressibility; Laws of pneumatics; Leverage; Air properties and flow; Bernoulli's Law; Components

Learning Objectives:

• Explain how force is transmitted in a pneumatic system.
• Calculate force and work.
• List two factors that affect the results of pressure calculations.
• Explain pneumatic leverage.
• Briefly explain the physical laws affecting the behavior of a confined gas.

Chapter 2: Directional Control Valves

Topics: Manually and automatically operated valves; Control valve elements: spools, poppets, disks, and plates; Two-, three-, four-, and five-way valves; Accessories

Learning Objectives:

• Describe the four methods of identifying control valves.
• List four basic types of manually operated, two-way
• Describe the operation of a two-position, direct acting,
• Explain one major advantage of using a four-way
• Describe the construction of a three-way valve.

Chapter 3: Pressure Control Valves

Topics: Safety vs relief valves; Relief valve construction; Pressure regulators; Pilot-operated, remote-controlled regulators; Logic functions

Learning Objectives:

• List two ways a valve can control compressor pressure output.
• Describe construction of two basic types of pressure-relief valves.
• Contrast a pressure regulator with a pressure-relief valve.
• State the limit imposed by Federal Law on the pressure allowed when an air hose is used to blow off chips.

Chapter 4: Pneumatic Cylinders

Topics: Double-, single-acting cylinders; Two-piston cylinders; Cylinder construction, mounting, and selection; Performance charts; Cushioning

Learning Objectives:

• Tell the difference between pneumatic and hydraulic cylinders.
• Describe the construction and operation of a single-acting cylinder.
• State the purpose of an exhaust flow control metering valve.
• Describe the action of a pivoted cylinder.
• Explain the size relationship between a cylinder port and a valve port.

Chapter 5: Pneumatic Systems

Topics: Air supply system; Reciprocating and rotary compressors; Cooling; Compressor maintenance; Air-line filters and lubrication

Learning Objectives:

• Explain the operation of linear actuators-cylinders-in a typical pneumatic circuit.
• Describe the various types of compressors and how they work.
• Define intercooling and aftercooling.
• Describe basic preventive maintenance procedures for compressors.
• List the components of an effective delivered-air system and explain how they work together.
• Describe the three main types of air-line lubrication.

Chapter 6: Installing Pneumatic Components

Topics: Compressor intakes and foundations; Aftercoolers; Receivers; Dryers; Pipe installation and support; Tubing and hose fittings; System installation

Learning Objectives:

• Describe the proper installation of the compressor and its auxiliaries.
• Describe the installation of aftercoolers, receivers, and dryers.
• Explain the correct procedures for installing pipes, tubes, and hoses in pneumaticsystems.
• Describe the installation of control valves, solenoid coils, and cylinders.

Chapter 7: System Maintenance

Topics: Control system maintenance; Cylinder maintenance; Tool maintenance; Logs and records; Automatic recorders and recording charts

Learning Objectives:

• Explain the concept of planned maintenance.
• Describe the basic procedures for maintaining the compressor and other important components in a pneumatic system.
• Describe the maintenance of industrial control circuit components.
• Explain the proper maintenance of pneumatic tools.
• Discuss the various types of maintenance logs and explain what kind of information is recorded in each.

Chapter 8: System Troubleshooting

Topics: Locating troubles; Operations manual; Checking the air supply; Troubleshooting valves and actuators; Interlocks; Final adjustments

Learning Objectives:

• List, in proper sequence, the steps to be taken in troubleshooting a pneumatic system.
• Name and describe the five important parts of every pneumatic system's operations manual.
• Describe procedures for troubleshooting the actuator.
• Explain how to check control valves, sequence valves, and interlocks.

Chapter 9: Directional Control Valves

Topics: Valve classification; Automatic, two-way, check, pilot-operated, and spool valves; Hydraulic motors; NO, NC, holding valves; Symbols; Flow ratings

Learning Objectives:

• Explain the classification of directional control valves.
• Describe how manually operated valves work.
• Explain the difference between direct-acting and pilot-operated valves.
• Describe the operation of a check valve, a spool valve, a three-way valve, a four-way valve, and a rotary valve.
• Explain the difference between normally closed and normally open valves.

Chapter 10: Pressure Control Valves

Topics: Poppet, spool, sequence, counterbalance, holding, unloading, and pressure-reducing valves; Shock suppressors; Flow-control valves

Learning Objectives:

• Explain the functions of a pressure-control valve, a pressure-relief valve, and a pressurereducing valve.
• Describe the operation of a spool valve, a poppet valve, and a sequence valve.
• Explain the purpose of holding valves, unloading valves, and counterbalance valves.
• Name the operations performed by flow-control valves.
• Describe how pressure compensation and temperature compensation work.

Chapter 11: Hydraulic Cylinders

Topics: Double-, single-acting cylinders; Two-piston cylinders; Positional cylinders; Cylinder construction; Rings, seals, and packing; Cylinder mounting and selection; Flow capacity; Cushioning

Learning Objectives:

• Describe the purpose of a hydraulic cylinder, and explain how a double-acting cylinder works.
• Explain the difference between "pull-type" and "push-type" single-acting cylinders.
• Describe the construction of a hydraulic cylinder.
• Explain the various methods of mounting cylinders.
• Demonstrate how to calculate the flow capacity of a hydraulic cylinder.

Chapter 12: Maintaining Hydraulic Systems

Topics: Inspections; Maintenance requirements; Fluid level; External leaks; Operating pressure; Fluid quality; Filter maintenance; Reconditioning

Learning Objectives:

• List the major categories of hydraulic system maintenance.
• Name and describe the six essential items in a maintenance file.
• List the steps involved in reconditioning a hydraulic component.
• Explain how to set up a maintenance plan for a typical hydraulic system.

Chapter 13: System Troubleshooting

Topics: Diagnosis and symptoms; Evaluating machine history; Determining the cause; Providing the solution; Tools and gauges; Troubleshooting charts

Learning Objectives:

• Describe the troubleshooting process.
• Explain how to evaluate recent maintenance history.
• List typical symptoms of common hydraulic system problems.
• Explain how to determine the cause of and provide a solution to a problem.
• Explain how a portable tester works.
• Describe how to keep and use troubleshooting charts.

Chapter 14: Valve Troubleshooting

Topics: Valve problems and test procedures; Disassembly, cleaning, and inspection; Repair and replacement; Solenoid problems; Reassembly and testing

Learning Objectives:

• Name five common valve problems and explain the sequence of steps to be followed in troubleshooting them.
• Describe the proper procedures for valve disassembly, cleaning, and inspection.
• Explain how to determine whether to repair or replace a malfunctioning valve.
• Describe the reasons for hydraulic "wire drawing."
• List the reasons for electrical and mechanical failures of solenoid valves.
• Explain the procedures for reassembling, reinstalling, and testing valves.

Chapter 15: Cylinder Troubleshooting

Topics: Cylinder descriptions; Troubleshooting procedures; Cylinder testing, repair, and installation; Shock absorbers

Learning Objectives:

• Name the most common types of hydraulic cylinders and identify their major parts.
• List the symptoms of internal and external cylinder misalignment.
• Explain what to do if you find internal leakage in a cylinder.
• Name the cylinder components most frequently replaced.
• Explain the purpose of a piston rod boot.
• Describe the symptoms of shock absorber failure.

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