SKMT 222 - Hydraulics and Pneumatics II

1. Discuss objectives learned in Hydraulics/Pneumatics I.
   1. Remember the schematic symbols used in Hydraulic or Pneumatic drawings.
   2. Find and locate these symbols in both textbooks.
   3. Identify and locate these symbols on drawings.
   4. Locate components in circuits and identify where these components should be located within a circuit.
   5. Use a drawing to state that the specific circuit does “……etc……”.
   6. State the basic laws of Hydraulics and Pneumatics such as “Pascal’s Law” and the “Pressure-Force-Area triangle”.
2. Explain basic components of a circuit.
   1. Cartridge valves:
      1. Identify the differences between “screw-in” type and “slip-in” type.
      2. Understand “screw-in” type always needs a pilot, “slip-in” type does not.
      3. List advantages and disadvantages of each.
      4. Identify examples of each of their respective uses. Examples: pressure control, directional control, and flow control.
   2. Proportioning valves:
      1. Understand they may be used in conjunction with or replace regular directional, flow, and pressure control valves.
      2. Understand they are strictly an electric operation.
      3. Understand they are very precise in their movements.
      4. Understand dirty factory environments can cause friction between the moving parts and disrupt precise movements. To counteract this, we superimpose a low amplitude AC signal referred to as “Dither”.
   3. Servo valves:
      1. Understand they are essentially infinite positioning directional valves.
      2. Understand they can be either electrical or mechanical operated.
      3. Understand they can be either single stage or “pilot and slave”.
      4. Understand they are much closer to the desired optimum performance than proportioning valves.
3. Build circuits on trainers from drawings.
   1. Hydrostatic transmissions.
   2. Regenerative circuits.
   3. Intensifier circuits.
   4. Accumulator circuits.
4. Recognize that normal conditions in any system will cause pressure drops.
   1. Apply the materials presented in class, working on the trainers, and using a chart in the Pease textbook (page 185) to determine potential pressure drops in a system using the following information:
      1. Piping diameter.
      2. Distance of travel of fluid.
      3. Number of turns and bends in the lines.
      4. Velocity of the fluid (usually in feet-per-second).
      5. Displacement of fluid (example: gallons-per-minute).
5. Recognize the hydraulic circuitry in an automotive automatic transmission.
   1. Explain how a torque converter works.
   2. Locate the hydraulic pump, explain how it is driven, and state what type of pump it is (usually a gear type).
   3. Locate the hydraulically operated brakes and clutches.
   4. Locate the planetary gear systems operated by the hydraulic brakes and clutches and explain how they are operated by the hydraulic brakes and clutches and that each gear speed of the transmission has its own planetary gear set.
   5. Understand directional valves route hydraulic pressure to the respective brake and clutch of the specific planetary gear set.
   6. Recognize that the shifting of the directional valves is controlled by vacuum, tachometer, and electronics, with electronics more so today.
6. Work with and maintain fluid power equipment in a safe manner.
   1. Recognize the proper way to lockout or disable fluid power equipment in order to work on it in a safe manner.
   2. Recognize the sequence of operations of fluid power machinery in order to determine what should or should not happen in order for it to be operated in a safe manner.
   3. Describe how to locate the proper replacement parts to be used to properly perform a repair job.
   4. Use the proper tools when performing maintenance or repairs on fluid power equipment.
7. Use fluid power with vacuum and pneumatics as the median.
   1. Compare vacuum with pneumatics.
   2. State some uses of a vacuum: a) lifting, b) molding, c) suction
   3. Explain that a vacuum is the difference