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AIT 115 - Hydraulic Systems

1. Read and interpret basic fluid power schematics including identifying schematic symbols, process flow, and operation of the components and systems.
2. Start up and shut down a hydraulic system, and adjust hydraulic pressure control valves in a system that uses a fixed displacement pump.
3. Select and adjust hydraulic actuator speed using a flow control valve.
4. Inspect and change a hydraulic filter; and inspect, add, change hydraulic fluid.
5. Connect, adjust, and disconnect flexible and rigid hydraulic conductors.
6. Install, test, and troubleshoot the operation of components in a basic hydraulic linear or rotary actuator given a schematic.

1. Employ mechanical fabrication procedures.

1. Basic Fluid Power Schematics (e.g. Identifying Schematic Symbols, Process Flow, Operation of the Components/Systems)
   1. Basic hydraulic components (given NFPA/ISO schematic symbol)
   2. Operation of circuits using:
      1. Single stage hydraulic direction control valves with manual and electrical operators
      2. Two stage hydraulic direction control valves with manual and electrical operators
      3. Various types of: spool centers, 2-position/3-position and 2/3/4 way designs
   3. Operation of hydraulic circuits (e.g. using accumulators, pump uploading, remote pressure control, rapid traverse slow feed, pilot-operated check valves)
   4. Interpretation of hydraulic line types on a schematic
   5. Operation of a basic hydraulic circuit (given a schematic)
   6. Basic pneumatic components (given their NFPA/ISO schematic symbol) identification
   7. Pneumatic line types on a schematic
   8. Operation of a basic pneumatic circuit given a schematic
2. Start Up/Shut Down a Hydraulic System; Adjust Hydraulic Pressure Control Valves in a System that Uses a Fixed Displacement Pump
   1. Start up a hydraulic power system safely (including pre-start inspection)
   2. Shut down a hydraulic power system safely
   3. Manufacturer’s documentation per specific application to determine correct operating pressure
   4. Reading a pressure gauge
   5. Adjusting system operating pressure using a relief valve
   6. Manual valves operation (to direct system flow)
   7. Adjusting pressure of a pressure reducing valve
   8. Adjusting system operating pressure
   9. Pressure-flow characteristics of types of:
      1. Relief valves
      2. Direct and pilot operated
   10. Operation of:
       1. Double acting cylinder
       2. Motor
       3. Hydraulic sequence valve
       4. Pressure reducing valve
   11. Pressure-flow characteristics of displacement pumps:
       1. Fixed
       2. Variable
   12. How to do pressure checks and charge accumulators
   13. Pressure vs. force/torque output characteristics of cylinders and motors
   14. Pascal’s law, its importance in reading system pressure
3. Selecting/Adjusting Hydraulic Actuator Speed (Using a Flow Control Valve)
   1. Actuator speed adjustment using:
      1. Needle valve
      2. Non-compensated flow control valves
      3. Compensated flow control valves
   2. Flow control valves adjustment in meter-in and meter-out configurations
   3. Measuring actuator speed
   4. Operation of:
      1. Needle valve
      2. Flow control valve
      3. Compensated flow control valve
      4. Meter-in circuits
      5. Meter-out circuits
   5. Flow vs. speed characteristics of a hydraulic cylinder and a motor
   6. Calculating pump flow rate requirements (given actuator speeds and sizes)
   7. Calculating pump flow rate (given pump size and speed)
4. Inspecting/Changing a Hydraulic Filter to Maximize Hydraulic Fluid Cleanliness
   1. Interpreting filter specifications/models to determine correct filter
   2. Manufacturer’s documentation to determine frequency of change
   3. When to replace a filter based on pressure differential across the filter
   4. Measuring pressure differential across a filter
   5. Replacing:
      1. Spin-on filter
      2. Cartridge filter
   6. Symptoms of a required strainer
   7. Replacing strainer
5. Inspecting, Adding, and Changing a Hydraulic Fluid
   1. Inspecting fluid levels through level gauge; determining when to add fluid
   2. Adding fluid to a hydraulic system
   3. Replacing hydraulic fluid using a filter cart
   4. Fluid inspection through sight, touch, and smell to determine if it should be replaced
   5. Fluid inspection for water and visible contaminants
   6. Water and contaminants removal from a hydraulic system (including, but not limited to, flushing and refilling system)
   7. Interpreting oil specifications (i.e. to determine if an oil meets the specifications specified by the machine manufacturer)
   8. Manufacturer’s documentation to determine the correct oil to use in a hydraulic system
   9. Taking fluid sample, preparing for submittal to a testing lab
6. Connecting, Adjusting, and Disconnecting Flexible and Rigid Hydraulic Conductors
   1. Interpreting pipe, hose, and tubing specifications
   2. Identification of type and size of hose, tubing, and hydraulic fittings (given a sample)
   3. Safety procedures to make sure pressure is removed before disconnecting conductors
   4. Proper fitting tightening; consequences of over-tightening
   5. How to attach/tighten:
      1. Hydraulic steel tubing, using wrenches and ferrule fittings
      2. Hydraulic fittings to components with threaded ports, using wrenches and applicable thread sealant
      3. Hydraulic hose, using wrenches and swivel fittings
      4. Hydraulic hose, using wrenches and straight thread O-ring fittings
   6. Adjusting the position and alignment of conductors for proper operation
   7. How to make hydraulic hose using proper fittings
   8. O-ring
      1. Operation
      2. Installation
      3. How specified
7. Installing, Testing the Operation of Components in a Basic Hydraulic Linear or Rotary Actuator (Given a Schematic)
   1. Installing/connecting hydraulic components in basic functional circuit (given a schematic)
   2. Replacing subplate-mounted directional, flow, and pressure control valves in a hydraulic system
   3. Replacing a threaded port valve
   4. Mounting/aligning a hydraulic cylinder or a motor
   5. Types of cylinder and motor mounting methods, and their applications
   6. Operating a hydraulic system to determine that it is performing correctly
   7. Proper bleeding procedures of a hydraulic system following component replacement
8. Troubleshooting a Basic Hydraulic Linear or Rotary Actuator Circuit
   1. Basic components in a hydraulic circuit using in-circuit tests troubleshooting
   2. Using flow and pressure instruments to take hydraulic circuit readings during in-circuit testing
   3. Flow vs. pressure drop characteristics of components and conductors and their impact on system operation
   4. Systematic methodologies to troubleshoot basic hydraulic circuits with linear and rotary actuators
   5. Types of failure of basic hydraulic components

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