Hydraulic systems

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  1. Virtually all modern airplanes use a simple hydraulic system to operate the _____
  2. A hydaulic system must contain 4 basic types of units.
    • Fluid supply
    • Pump
    • Actuator
    • Selector valve
  3. A single unit containing an electrically driven hydraulic pump, reservoir, control valve and many of the auxiliary valves is known as a hydraulic _______ system.
  4. The two types of hydraulic reservoirs are:
    • Integral (in another component, like a transmission)
    • In-line (inside its own housing , connected by hoses)
  5. Aircraft that operate in the lower altitudes normally use _______ reservoirs
  6. 3 ways to pressurize hydraulic reservoirs:
    • aspirator (by jet action draws more air into reservoir)
    • bleed air
    • hydraulic piston
  7. One micron is equal to ___ inch.
    .000039 inch or 1 millionth of a meter
  8. Pleated paper micronic filters are usually installed in the hydraulic system pressure or return line?
  9. Cuno filters can or cannot be used on the pressure side of the system?
    Used on pressure side
  10. Hand pumps are usually single or double acting?
    piston rod displacement double acting
  11. Which type of pump moves a specific volume of fluid each time its shaft turns
    Constant displacement
  12. What type of valve is needed when a constant displacement pump is used?
    regulator or relief valve
  13. A gear type hydraulic pump is a ________ pump.
    constant displacement
  14. A hydraulic system using a variable displacement pump does or does not require an unloading valve.
  15. A selector valve is one of the most common type of ____ (flow or pressure) control valve.
  16. The (open or closed) center valve directs fluid through the center of the valve back to the reservoir when a unit is not being actuated.
    open center
  17. A valve that allows fliud to flow in one direction but no flow in the opposite direction is called ?
    Check Valve
  18. AA valve that allows fliud to flow in one direction but a restricted flow in the other direction is called ?
    Orifice check valve
  19. A valve that required one component to fully actuate before another can actuate is called ?
    Sequence valves
  20. Sequence valves are opened mechanically or hydraulically?
  21. Priority valves are opened mechanically or hydraulicly?
  22. Similar to a sequence valve but opened by hydraulic pressure instead of mechanical contact?
  23. What can be installed to block a line in case of a serious leak?
    Hydraulic fuse
  24. Two principles upon which a hydraulic fuse operates?
    • Pressure drop
    • Volume limiting
  25. The simplest type of pressure control valve is ?
    Relief valve
  26. What may be installed when it is necessary to operate some portion of a hydraulic system at a pressure lower that normal system pressure?
    Pressure reducer
  27. What device is used to store hydraulic pressure?
  28. One compartment of an accumulator is connected to the hydraulic system while the other side is filled with?
    Nitrogen or Dry air
  29. What are the 3 types of accumulators?
    • Piston
    • Diaphragm
    • Bladder
  30. AN812 valve cores are identified by what letter embossed on their stem?
  31. Which air valve has these features?
    -No core
    - Metal to metal seal
    -Swivel nut to open and close , same size as valve body
    AN812, AN6287-1, or MS28889-1
  32. How many different types of air valves are used in aircraft?
  33. Which air valve has these features?
    -"H" stamped on stem
    -Similar to automotive
    -Core is used to seal
    AN812, AN6287-1, or MS 28889-1
  34. What air valves have these features?
    -Metal to metal seal
    -opened and closed by swivel nut smaller than body of valve
    -Has a core
  35. Hydraulic actuators which produce a straight line movement are known as?
    Linear actuators
  36. If a continuous rotational force is needed , a hydraulic ____ is used.
  37. A chevron seal is a one or two way seal?
    One way
  38. An o-ring is a one or two way seal?
    two way
  39. An o-ring should have a width approx. 10% ____ than the width of its groove.
  40. What is used with an o-ring when the operating pressure exceeds 1500 psi?
    Back-up rings
  41. O-ring back-up rings are made of?
    Leather or Teflon
  42. The ______ date is the date of O-ring manufacture.
    cure date
  43. An o-ring marked with a blue dot is compatible with?
    Air or 5606
  44. When installing or removing o-rings , extreme care must be taken to prevent rings from being _____ by sharp edges.
    nick or cut
  45. O rings with red dots are used for?
  46. O-rings with a green dot are used with?
  47. O-rings with yellow dots are used with?
    synthetic engine oil
  48. O-rings with a white dot are used with?
    petroleum engine oil
  49. Name 4 one way seals.
    • D-ring
    • U-ring
    • V-ring
    • Chevron
  50. What is used to prevent loss of fluid when hydraulic units are replaced?
    Quick disconnect valves
  51. What is an example of a variable displacement pump?
    Piston pump
  52. What are 2 types of check valves?
    • Integral
    • in-line
  53. What are the 4 types of linear actuators
    • Single acting
    • double acting balanced
    • double acting unbalanced
    • cushioned
  54. What is meant by a tandem actuator.
    2 actuators built into one unit
  55. Actuators that contain a control valve are generally called.
    hydraulic servos
Card Set:
Hydraulic systems

ame aircraft maintenance hydraulics hydraulic systems airframe
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