Hydraulic Troubleshooting

Table of Contents

Chapter 1: Tracing Hydraulic Systems

Topics: System components; Hydraulic fluids; Tracing the system; Schematics; Cutaway drawings; Mechanical setup

Learning Objectives:

• Name the six basic elements of a hydraulic system.
• Explain the functions of hydraulic pumps, actuators, control valves, conductors and connectors, hydraulic fluid, and fluid storage and conditioning equipment.
• Describe how to trace a system.

Chapter 2: Hydraulic Diagrams

Topics: Definition, kinds, and characteristics of schematics; Lines; Symbols; Flow patterns; Tracing a circuit; Sequence valve circuit

Learning Objectives:

• Name three basic types of hydraulic diagrams, and explain the purposes of each.
• Describe how a valve symbol is constructed.
• List the steps to follow when reading a schematic diagram.
• Identify common hydraulic symbols.

Chapter 3: Installing Hydraulic Components

Topics: Safety; Cleanliness; Pump, drive, control valves, and mechanical valve installations; Pump start-up; Valve port identification

Learning Objectives:

• Explain the importance of cleanliness in hydraulic installations.
• Describe possible consequences of neglecting safety precautions.
• Explain how motor and pump shafts are aligned before coupling.
• Explain the correct method for checking direction of pump rotation.
• List several useful hints for solenoid valve installation.

Chapter 4: Installing Piping and Tubing

Topics: General installation procedures; Tube flaring; Checking the flare; Tube bending and assembly; Hose, seal, reservoir, filter, heat exchanger, and actuator installation

Learning Objectives:

• Explain how pipe sizes are specified.
• Name the common types of pipe joints.
• List six important rules for good piping installation.
• Describe the advantages of hydraulic tubing over pipes.
• Describe the correct methods for bending and flaring tubing.
• List the key points for correctly installing hydraulic hoses, seals, reservoirs, filters, and actuators.

Chapter 5: Selecting Hydraulic Fluids

Topics: Viscosity; Resistance to chemical and physical changes; Low-temperature properties; Demulsibility; Antirust properties; Compatibility

Learning Objectives:

• List ten important properties of hydraulic fluids.
• Explain the difference between hydrodynamic and boundary lubrication.
• Explain what a fluid's viscosity index means.
• Define demulsibility and emulsibility.
• Describe how to read a viscosity-temperature chart.
• List the proper procedures for installing hydraulic fluid.

Chapter 6: 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 7: 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 8: 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 9: 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.

Chapter 10: Pump and Motor Troubleshooting

Topics: Gear and vane pump problems; Vane motors; Axial- and radial-piston pump problems; Pump and motor repair; Pump maintenance checks

Learning Objectives:

• List the proper procedures for troubleshooting pumps and motors.
• Name some common causes of pump failure.
• Describe typical causes of cavitation.
• Discuss the major sources of problems in gear pumps and vane pumps.
• Describe the effects of contaminants in axial-piston and radial-piston pumps.
• Explain the differences between a vane motor and a vane pump.

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