Hydraulic Troubleshooting

Lesson 1 - 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.

Lesson 2 - Hydraulic Schematic 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.

Lesson 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.

Lesson 4 - Installing Pipes and Tubes

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.

Lesson 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.

Lesson 6 - Planning System Maintenance

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.

Lesson 7 - Troubleshooting Systems

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.

Lesson 8 - Troubleshooting Valves

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.

Lesson 9 - Troubleshooting Cylinders

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.

Lesson 10 - Troubleshooting Pumps and Motors

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.